topreal2.miz
    
    begin
    
    reserve a for
    set;
    
    reserve p,p1,p2,q,q1,q2 for
    Point of ( 
    TOP-REAL 2); 
    
    reserve h1,h2 for
    FinSequence of ( 
    TOP-REAL 2); 
    
    
    
    
    
    Lm1: for x,X be 
    set st not x 
    in X holds ( 
    {x}
    /\ X) 
    =  
    {} by 
    XBOOLE_0:def 7,
    ZFMISC_1: 50;
    
    
    
    
    
    Lm2: (( 
    LSeg ( 
    |[
    0 , 
    0 ]|, 
    |[1,
    0 ]|)) 
    /\ ( 
    LSeg ( 
    |[
    0 , 1]|, 
    |[1, 1]|)))
    =  
    {} by 
    TOPREAL1: 19,
    XBOOLE_0:def 7;
    
    
    
    
    
    Lm3: (( 
    LSeg ( 
    |[
    0 , 
    0 ]|, 
    |[
    0 , 1]|)) 
    /\ ( 
    LSeg ( 
    |[1,
    0 ]|, 
    |[1, 1]|)))
    =  
    {} by 
    TOPREAL1: 20,
    XBOOLE_0:def 7;
    
    set p00 =
    |[
    0 , 
    0 ]|, p01 = 
    |[
    0 , 1]|, p10 = 
    |[1,
    0 ]|, p11 = 
    |[1, 1]|, L1 = (
    LSeg (p00,p01)), L2 = ( 
    LSeg (p01,p11)), L3 = ( 
    LSeg (p00,p10)), L4 = ( 
    LSeg (p10,p11)); 
    
    
    
    
    
    Lm4: (p00 
    `1 ) 
    =  
    0 by 
    EUCLID: 52;
    
    
    
    
    
    Lm5: (p00 
    `2 ) 
    =  
    0 by 
    EUCLID: 52;
    
    
    
    
    
    Lm6: (p01 
    `1 ) 
    =  
    0 by 
    EUCLID: 52;
    
    
    
    
    
    Lm7: (p01 
    `2 ) 
    = 1 by 
    EUCLID: 52;
    
    
    
    
    
    Lm8: (p10 
    `1 ) 
    = 1 by 
    EUCLID: 52;
    
    
    
    
    
    Lm9: (p10 
    `2 ) 
    =  
    0 by 
    EUCLID: 52;
    
    
    
    
    
    Lm10: (p11 
    `1 ) 
    = 1 by 
    EUCLID: 52;
    
    
    
    
    
    Lm11: (p11 
    `2 ) 
    = 1 by 
    EUCLID: 52;
    
    
    
    
    
    Lm12: not p00 
    in L4 by 
    Lm4,
    Lm8,
    Lm10,
    TOPREAL1: 3;
    
    
    
    
    
    Lm13: not p00 
    in L2 by 
    Lm5,
    Lm7,
    Lm11,
    TOPREAL1: 4;
    
    
    
    
    
    Lm14: not p01 
    in L3 by 
    Lm5,
    Lm7,
    Lm9,
    TOPREAL1: 4;
    
    
    
    
    
    Lm15: not p01 
    in L4 by 
    Lm6,
    Lm8,
    Lm10,
    TOPREAL1: 3;
    
    
    
    
    
    Lm16: not p10 
    in L1 by 
    Lm4,
    Lm6,
    Lm8,
    TOPREAL1: 3;
    
    
    
    
    
    Lm17: not p10 
    in L2 by 
    Lm7,
    Lm9,
    Lm11,
    TOPREAL1: 4;
    
    
    
    
    
    Lm18: not p11 
    in L1 by 
    Lm4,
    Lm6,
    Lm10,
    TOPREAL1: 3;
    
    
    
    
    
    Lm19: not p11 
    in L3 by 
    Lm5,
    Lm9,
    Lm11,
    TOPREAL1: 4;
    
    
    
    
    
    Lm20: p00 
    in L1 by 
    RLTOPSP1: 68;
    
    
    
    
    
    Lm21: p00 
    in L3 by 
    RLTOPSP1: 68;
    
    
    
    
    
    Lm22: p01 
    in L1 by 
    RLTOPSP1: 68;
    
    
    
    
    
    Lm23: p01 
    in L2 by 
    RLTOPSP1: 68;
    
    
    
    
    
    Lm24: p10 
    in L3 by 
    RLTOPSP1: 68;
    
    
    
    
    
    Lm25: p10 
    in L4 by 
    RLTOPSP1: 68;
    
    
    
    
    
    Lm26: p11 
    in L2 by 
    RLTOPSP1: 68;
    
    
    
    
    
    Lm27: p11 
    in L4 by 
    RLTOPSP1: 68;
    
    set L = { p : (p
    `1 ) 
    =  
    0 & (p 
    `2 ) 
    <= 1 & (p 
    `2 ) 
    >=  
    0 or (p 
    `1 ) 
    <= 1 & (p 
    `1 ) 
    >=  
    0 & (p 
    `2 ) 
    = 1 or (p 
    `1 ) 
    <= 1 & (p 
    `1 ) 
    >=  
    0 & (p 
    `2 ) 
    =  
    0 or (p 
    `1 ) 
    = 1 & (p 
    `2 ) 
    <= 1 & (p 
    `2 ) 
    >=  
    0 }; 
    
    
    
    
    
    Lm28: p00 
    in L by 
    Lm4,
    Lm5;
    
    
    
    
    
    Lm29: p11 
    in L by 
    Lm10,
    Lm11;
    
    
    
    
    
    Lm30: p1 
    <> p2 & p2 
    in  
    R^2-unit_square & p1 
    in ( 
    LSeg (p00,p01)) implies ex P1,P2 be non 
    empty  
    Subset of ( 
    TOP-REAL 2) st P1 
    is_an_arc_of (p1,p2) & P2 
    is_an_arc_of (p1,p2) & 
    R^2-unit_square  
    = (P1 
    \/ P2) & (P1 
    /\ P2) 
    =  
    {p1, p2}
    
    proof
    
      assume that
    
      
    
    A1: p1 
    <> p2 and 
    
      
    
    A2: p2 
    in  
    R^2-unit_square and 
    
      
    
    A3: p1 
    in ( 
    LSeg (p00,p01)); 
    
      
    
      
    
    A4: ( 
    LSeg (p00,p1)) 
    c= L1 by 
    A3,
    Lm20,
    TOPREAL1: 6;
    
      p00
    in ( 
    LSeg (p1,p00)) by 
    RLTOPSP1: 68;
    
      then p00
    in (( 
    LSeg (p1,p00)) 
    /\ L3) by 
    Lm21,
    XBOOLE_0:def 4;
    
      then
    
      
    
    A5: 
    {p00}
    c= (( 
    LSeg (p1,p00)) 
    /\ L3) by 
    ZFMISC_1: 31;
    
      
    
      
    
    A6: (( 
    LSeg (p1,p00)) 
    /\ L3) 
    c= (L1 
    /\ L3) by 
    A3,
    Lm20,
    TOPREAL1: 6,
    XBOOLE_1: 26;
    
      then
    
      
    
    A7: (( 
    LSeg (p1,p00)) 
    /\ L3) 
    =  
    {p00} by
    A5,
    TOPREAL1: 17,
    XBOOLE_0:def 10;
    
      
    
      
    
    A8: (L1 
    /\ L4) 
    =  
    {} by 
    TOPREAL1: 20,
    XBOOLE_0:def 7;
    
      then
    
      
    
    A9: (( 
    LSeg (p1,p00)) 
    /\ L4) 
    =  
    {} by 
    A4,
    XBOOLE_1: 3,
    XBOOLE_1: 26;
    
      p01
    in ( 
    LSeg (p01,p1)) by 
    RLTOPSP1: 68;
    
      then p01
    in (( 
    LSeg (p01,p1)) 
    /\ L2) by 
    Lm23,
    XBOOLE_0:def 4;
    
      then
    
      
    
    A10: 
    {p01}
    c= (( 
    LSeg (p01,p1)) 
    /\ L2) by 
    ZFMISC_1: 31;
    
      
    
      
    
    A11: p2 
    in (L1 
    \/ L2) or p2 
    in (L3 
    \/ L4) by 
    A2,
    TOPREAL1:def 2,
    XBOOLE_0:def 3;
    
      
    
      
    
    A12: (( 
    LSeg (p01,p1)) 
    /\ L2) 
    c=  
    {p01} by
    A3,
    Lm22,
    TOPREAL1: 6,
    TOPREAL1: 15,
    XBOOLE_1: 26;
    
      
    
      
    
    A13: ( 
    LSeg (p1,p01)) 
    c= L1 by 
    A3,
    Lm22,
    TOPREAL1: 6;
    
      then
    
      
    
    A14: (( 
    LSeg (p01,p1)) 
    /\ L4) 
    =  
    {} by 
    A8,
    XBOOLE_1: 3,
    XBOOLE_1: 26;
    
      consider p such that
    
      
    
    A15: p 
    = p1 and 
    
      
    
    A16: (p 
    `1 ) 
    =  
    0 and 
    
      
    
    A17: (p 
    `2 ) 
    <= 1 and 
    
      
    
    A18: (p 
    `2 ) 
    >=  
    0 by 
    A3,
    TOPREAL1: 13;
    
      per cases by
    A11,
    XBOOLE_0:def 3;
    
        suppose
    
        
    
    A19: p2 
    in L1; 
    
        then
    
        
    
    A20: ( 
    LSeg (p2,p1)) 
    c= L1 by 
    A3,
    TOPREAL1: 6;
    
        
    
        
    
    A21: p 
    =  
    |[(p
    `1 ), (p 
    `2 )]| by 
    EUCLID: 53;
    
        consider q such that
    
        
    
    A22: q 
    = p2 and 
    
        
    
    A23: (q 
    `1 ) 
    =  
    0 and 
    
        
    
    A24: (q 
    `2 ) 
    <= 1 and 
    
        
    
    A25: (q 
    `2 ) 
    >=  
    0 by 
    A19,
    TOPREAL1: 13;
    
        
    
        
    
    A26: q 
    =  
    |[(q
    `1 ), (q 
    `2 )]| by 
    EUCLID: 53;
    
        now
    
          per cases by
    A1,
    A15,
    A16,
    A22,
    A23,
    A21,
    A26,
    XXREAL_0: 1;
    
            case
    
            
    
    A27: (p 
    `2 ) 
    < (q 
    `2 ); 
    
            
    
            
    
    A28: (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p1,p00))) 
    c=  
    {p1}
    
            proof
    
              let a be
    object;
    
              assume
    
              
    
    A29: a 
    in (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p1,p00))); 
    
              then
    
              reconsider p = a as
    Point of ( 
    TOP-REAL 2); 
    
              
    
              
    
    A30: p 
    in ( 
    LSeg (p00,p1)) by 
    A29,
    XBOOLE_0:def 4;
    
              (p00
    `2 ) 
    <= (p1 
    `2 ) by 
    A15,
    A18,
    EUCLID: 52;
    
              then
    
              
    
    A31: (p 
    `2 ) 
    <= (p1 
    `2 ) by 
    A30,
    TOPREAL1: 4;
    
              
    
              
    
    A32: p 
    in ( 
    LSeg (p1,p2)) by 
    A29,
    XBOOLE_0:def 4;
    
              then (p1
    `2 ) 
    <= (p 
    `2 ) by 
    A15,
    A22,
    A27,
    TOPREAL1: 4;
    
              then
    
              
    
    A33: (p1 
    `2 ) 
    = (p 
    `2 ) by 
    A31,
    XXREAL_0: 1;
    
              (p1
    `1 ) 
    <= (p 
    `1 ) by 
    A15,
    A16,
    A22,
    A23,
    A32,
    TOPREAL1: 3;
    
              then (p
    `1 ) 
    =  
    0 by 
    A15,
    A16,
    A22,
    A23,
    A32,
    TOPREAL1: 3;
    
              
    
              then p
    =  
    |[
    0 , (p1 
    `2 )]| by 
    A33,
    EUCLID: 53
    
              .= p1 by
    A15,
    A16,
    EUCLID: 53;
    
              hence thesis by
    TARSKI:def 1;
    
            end;
    
            
    
            
    
    A34: (( 
    LSeg (p01,p2)) 
    /\ L2) 
    c= (L1 
    /\ L2) by 
    A19,
    Lm22,
    TOPREAL1: 6,
    XBOOLE_1: 26;
    
            
    
    A35: 
    
            now
    
              set a = the
    Element of (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p01,p2))); 
    
              assume
    
              
    
    A36: (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p01,p2))) 
    <>  
    {} ; 
    
              then
    
              reconsider p = a as
    Point of ( 
    TOP-REAL 2) by 
    TARSKI:def 3;
    
              
    
              
    
    A37: p 
    in ( 
    LSeg (p00,p1)) by 
    A36,
    XBOOLE_0:def 4;
    
              
    
              
    
    A38: p 
    in ( 
    LSeg (p2,p01)) by 
    A36,
    XBOOLE_0:def 4;
    
              (p2
    `2 ) 
    <= (p01 
    `2 ) by 
    A22,
    A24,
    EUCLID: 52;
    
              then
    
              
    
    A39: (p2 
    `2 ) 
    <= (p 
    `2 ) by 
    A38,
    TOPREAL1: 4;
    
              (p00
    `2 ) 
    <= (p1 
    `2 ) by 
    A15,
    A18,
    EUCLID: 52;
    
              then (p
    `2 ) 
    <= (p1 
    `2 ) by 
    A37,
    TOPREAL1: 4;
    
              hence contradiction by
    A15,
    A22,
    A27,
    A39,
    XXREAL_0: 2;
    
            end;
    
            p01
    in ( 
    LSeg (p01,p2)) by 
    RLTOPSP1: 68;
    
            then p01
    in (( 
    LSeg (p01,p2)) 
    /\ L2) by 
    Lm23,
    XBOOLE_0:def 4;
    
            then
    
            
    
    A40: 
    {p01}
    c= (( 
    LSeg (p01,p2)) 
    /\ L2) by 
    ZFMISC_1: 31;
    
            now
    
              assume p00
    in (( 
    LSeg (p01,p2)) 
    /\ L3); 
    
              then
    
              
    
    A41: p00 
    in ( 
    LSeg (p2,p01)) by 
    XBOOLE_0:def 4;
    
              (p2
    `2 ) 
    <= (p01 
    `2 ) by 
    A22,
    A24,
    EUCLID: 52;
    
              hence contradiction by
    A18,
    A22,
    A27,
    A41,
    Lm5,
    TOPREAL1: 4;
    
            end;
    
            then
    
            
    
    A42: 
    {p00}
    <> (( 
    LSeg (p01,p2)) 
    /\ L3) by 
    ZFMISC_1: 31;
    
            ((
    LSeg (p01,p2)) 
    /\ L3) 
    c=  
    {p00} by
    A19,
    Lm22,
    TOPREAL1: 6,
    TOPREAL1: 17,
    XBOOLE_1: 26;
    
            then
    
            
    
    A43: (( 
    LSeg (p01,p2)) 
    /\ L3) 
    =  
    {} by 
    A42,
    ZFMISC_1: 33;
    
            
    
            
    
    A44: (( 
    LSeg (p1,p2)) 
    /\ L3) 
    c=  
    {p00} by
    A3,
    A19,
    TOPREAL1: 6,
    TOPREAL1: 17,
    XBOOLE_1: 26;
    
            
    
            
    
    A45: (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p01,p2))) 
    c=  
    {p2}
    
            proof
    
              let a be
    object;
    
              assume
    
              
    
    A46: a 
    in (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p01,p2))); 
    
              then
    
              reconsider p = a as
    Point of ( 
    TOP-REAL 2); 
    
              
    
              
    
    A47: p 
    in ( 
    LSeg (p2,p01)) by 
    A46,
    XBOOLE_0:def 4;
    
              (p2
    `2 ) 
    <= (p01 
    `2 ) by 
    A22,
    A24,
    EUCLID: 52;
    
              then
    
              
    
    A48: (p2 
    `2 ) 
    <= (p 
    `2 ) by 
    A47,
    TOPREAL1: 4;
    
              
    
              
    
    A49: p 
    in ( 
    LSeg (p1,p2)) by 
    A46,
    XBOOLE_0:def 4;
    
              then (p
    `2 ) 
    <= (p2 
    `2 ) by 
    A15,
    A22,
    A27,
    TOPREAL1: 4;
    
              then
    
              
    
    A50: (p2 
    `2 ) 
    = (p 
    `2 ) by 
    A48,
    XXREAL_0: 1;
    
              (p1
    `1 ) 
    <= (p 
    `1 ) by 
    A15,
    A16,
    A22,
    A23,
    A49,
    TOPREAL1: 3;
    
              then (p
    `1 ) 
    =  
    0 by 
    A15,
    A16,
    A22,
    A23,
    A49,
    TOPREAL1: 3;
    
              
    
              then p
    =  
    |[
    0 , (p2 
    `2 )]| by 
    A50,
    EUCLID: 53
    
              .= p2 by
    A22,
    A23,
    EUCLID: 53;
    
              hence thesis by
    TARSKI:def 1;
    
            end;
    
            
    
            
    
    A51: (( 
    LSeg (p1,p00)) 
    /\ L2) 
    c=  
    {p01} by
    A3,
    Lm20,
    TOPREAL1: 6,
    TOPREAL1: 15,
    XBOOLE_1: 26;
    
            now
    
              assume p01
    in (( 
    LSeg (p1,p00)) 
    /\ L2); 
    
              then
    
              
    
    A52: p01 
    in ( 
    LSeg (p00,p1)) by 
    XBOOLE_0:def 4;
    
              (p00
    `2 ) 
    <= (p1 
    `2 ) by 
    A15,
    A18,
    EUCLID: 52;
    
              then (p01
    `2 ) 
    <= (p1 
    `2 ) by 
    A52,
    TOPREAL1: 4;
    
              hence contradiction by
    A15,
    A17,
    A24,
    A27,
    Lm7,
    XXREAL_0: 1;
    
            end;
    
            then
    
            
    
    A53: 
    {p01}
    <> (( 
    LSeg (p1,p00)) 
    /\ L2) by 
    ZFMISC_1: 31;
    
            set P1 = (
    LSeg (p1,p2)), P2 = (( 
    LSeg (p1,p00)) 
    \/ (((L3 
    \/ L4) 
    \/ ( 
    LSeg (p11,p01))) 
    \/ ( 
    LSeg (p01,p2)))); 
    
            
    
            
    
    A54: p1 
    in ( 
    LSeg (p1,p00)) by 
    RLTOPSP1: 68;
    
            
    
            
    
    A55: ( 
    LSeg (p01,p2)) 
    c= L1 by 
    A19,
    Lm22,
    TOPREAL1: 6;
    
            p1
    in ( 
    LSeg (p1,p2)) by 
    RLTOPSP1: 68;
    
            then p1
    in (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p1,p00))) by 
    A54,
    XBOOLE_0:def 4;
    
            then
    {p1}
    c= (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p1,p00))) by 
    ZFMISC_1: 31;
    
            then
    
            
    
    A56: (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p1,p00))) 
    =  
    {p1} by
    A28,
    XBOOLE_0:def 10;
    
            thus P1
    is_an_arc_of (p1,p2) by 
    A1,
    TOPREAL1: 9;
    
            
    
            
    
    A57: ((L3 
    \/ L4) 
    /\ ( 
    LSeg (p11,p01))) 
    = ( 
    {}  
    \/  
    {p11}) by
    Lm2,
    TOPREAL1: 18,
    XBOOLE_1: 23
    
            .=
    {p11};
    
            (L3
    \/ L4) 
    is_an_arc_of (p00,p11) by 
    Lm4,
    Lm8,
    TOPREAL1: 12,
    TOPREAL1: 16;
    
            then
    
            
    
    A58: ((L3 
    \/ L4) 
    \/ ( 
    LSeg (p11,p01))) 
    is_an_arc_of (p00,p01) by 
    A57,
    TOPREAL1: 10;
    
            (((L3
    \/ L4) 
    \/ ( 
    LSeg (p11,p01))) 
    /\ ( 
    LSeg (p01,p2))) 
    = ((( 
    LSeg (p01,p2)) 
    /\ (L3 
    \/ L4)) 
    \/ (( 
    LSeg (p01,p2)) 
    /\ ( 
    LSeg (p11,p01)))) by 
    XBOOLE_1: 23
    
            .= ((
    {}  
    \/ (( 
    LSeg (p01,p2)) 
    /\ L4)) 
    \/ (( 
    LSeg (p01,p2)) 
    /\ ( 
    LSeg (p11,p01)))) by 
    A43,
    XBOOLE_1: 23
    
            .= (
    {}  
    \/ (( 
    LSeg (p01,p2)) 
    /\ ( 
    LSeg (p11,p01)))) by 
    A55,
    Lm3,
    XBOOLE_1: 3,
    XBOOLE_1: 26
    
            .=
    {p01} by
    A40,
    A34,
    TOPREAL1: 15,
    XBOOLE_0:def 10;
    
            then
    
            
    
    A59: (((L3 
    \/ L4) 
    \/ ( 
    LSeg (p11,p01))) 
    \/ ( 
    LSeg (p01,p2))) 
    is_an_arc_of (p00,p2) by 
    A58,
    TOPREAL1: 10;
    
            ((
    LSeg (p1,p00)) 
    /\ (((L3 
    \/ L4) 
    \/ ( 
    LSeg (p11,p01))) 
    \/ ( 
    LSeg (p01,p2)))) 
    = ((( 
    LSeg (p1,p00)) 
    /\ ((L3 
    \/ L4) 
    \/ ( 
    LSeg (p11,p01)))) 
    \/ (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p01,p2)))) by 
    XBOOLE_1: 23
    
            .= ((((
    LSeg (p1,p00)) 
    /\ (L3 
    \/ L4)) 
    \/ (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p11,p01)))) 
    \/ (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p01,p2)))) by 
    XBOOLE_1: 23
    
            .= (((((
    LSeg (p1,p00)) 
    /\ L3) 
    \/ (( 
    LSeg (p1,p00)) 
    /\ L4)) 
    \/ (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p11,p01)))) 
    \/ (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p01,p2)))) by 
    XBOOLE_1: 23
    
            .=
    {p00} by
    A9,
    A7,
    A35,
    A51,
    A53,
    ZFMISC_1: 33;
    
            hence ((
    LSeg (p1,p00)) 
    \/ (((L3 
    \/ L4) 
    \/ ( 
    LSeg (p11,p01))) 
    \/ ( 
    LSeg (p01,p2)))) 
    is_an_arc_of (p1,p2) by 
    A59,
    TOPREAL1: 11;
    
            (((
    LSeg (p01,p2)) 
    \/ ( 
    LSeg (p2,p1))) 
    \/ ( 
    LSeg (p1,p00))) 
    = L1 by 
    A3,
    A19,
    TOPREAL1: 7;
    
            
    
            hence
    R^2-unit_square  
    = (((( 
    LSeg (p1,p2)) 
    \/ ( 
    LSeg (p01,p2))) 
    \/ ( 
    LSeg (p1,p00))) 
    \/ ((L3 
    \/ L4) 
    \/ ( 
    LSeg (p11,p01)))) by 
    TOPREAL1:def 2,
    XBOOLE_1: 4
    
            .= (((
    LSeg (p1,p2)) 
    \/ (( 
    LSeg (p1,p00)) 
    \/ ( 
    LSeg (p01,p2)))) 
    \/ ((L3 
    \/ L4) 
    \/ ( 
    LSeg (p11,p01)))) by 
    XBOOLE_1: 4
    
            .= ((
    LSeg (p1,p2)) 
    \/ ((( 
    LSeg (p1,p00)) 
    \/ ( 
    LSeg (p01,p2))) 
    \/ ((L3 
    \/ L4) 
    \/ ( 
    LSeg (p11,p01))))) by 
    XBOOLE_1: 4
    
            .= (P1
    \/ P2) by 
    XBOOLE_1: 4;
    
            
    
            
    
    A60: p2 
    in ( 
    LSeg (p01,p2)) by 
    RLTOPSP1: 68;
    
            p2
    in ( 
    LSeg (p1,p2)) by 
    RLTOPSP1: 68;
    
            then p2
    in (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p01,p2))) by 
    A60,
    XBOOLE_0:def 4;
    
            then
    {p2}
    c= (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p01,p2))) by 
    ZFMISC_1: 31;
    
            then
    
            
    
    A61: (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p01,p2))) 
    =  
    {p2} by
    A45,
    XBOOLE_0:def 10;
    
            
    
            
    
    A62: ( 
    LSeg (p1,p2)) 
    c= L1 by 
    A3,
    A19,
    TOPREAL1: 6;
    
            
    
            
    
    A63: (P1 
    /\ P2) 
    = ((( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p1,p00))) 
    \/ (( 
    LSeg (p1,p2)) 
    /\ (((L3 
    \/ L4) 
    \/ ( 
    LSeg (p11,p01))) 
    \/ ( 
    LSeg (p01,p2))))) by 
    XBOOLE_1: 23
    
            .= (((
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p1,p00))) 
    \/ ((( 
    LSeg (p1,p2)) 
    /\ ((L3 
    \/ L4) 
    \/ ( 
    LSeg (p11,p01)))) 
    \/ (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p01,p2))))) by 
    XBOOLE_1: 23
    
            .= (((
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p1,p00))) 
    \/ (((( 
    LSeg (p1,p2)) 
    /\ (L3 
    \/ L4)) 
    \/ (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p11,p01)))) 
    \/ (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p01,p2))))) by 
    XBOOLE_1: 23
    
            .= (
    {p1}
    \/ ((((( 
    LSeg (p1,p2)) 
    /\ L3) 
    \/ (( 
    LSeg (p1,p2)) 
    /\ L4)) 
    \/ (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p11,p01)))) 
    \/ (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p01,p2))))) by 
    A56,
    XBOOLE_1: 23
    
            .= (
    {p1}
    \/ ((((( 
    LSeg (p1,p2)) 
    /\ L3) 
    \/  
    {} ) 
    \/ (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p11,p01)))) 
    \/ (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p01,p2))))) by 
    A62,
    Lm3,
    XBOOLE_1: 3,
    XBOOLE_1: 26
    
            .= (
    {p1}
    \/ ((( 
    LSeg (p1,p2)) 
    /\ L3) 
    \/ ((( 
    LSeg (p1,p2)) 
    /\ L2) 
    \/  
    {p2}))) by
    A61,
    XBOOLE_1: 4
    
            .= ((
    {p1}
    \/ (( 
    LSeg (p1,p2)) 
    /\ L3)) 
    \/ ((( 
    LSeg (p1,p2)) 
    /\ L2) 
    \/  
    {p2})) by
    XBOOLE_1: 4;
    
            
    
    A64: 
    
            now
    
              per cases ;
    
                suppose
    
                
    
    A65: p1 
    = p00; 
    
                then p00
    in ( 
    LSeg (p1,p2)) by 
    RLTOPSP1: 68;
    
                then ((
    LSeg (p1,p2)) 
    /\ L3) 
    <>  
    {} by 
    Lm21,
    XBOOLE_0:def 4;
    
                then ((
    LSeg (p1,p2)) 
    /\ L3) 
    =  
    {p1} by
    A44,
    A65,
    ZFMISC_1: 33;
    
                hence (P1
    /\ P2) 
    = ( 
    {p1}
    \/ ((( 
    LSeg (p1,p2)) 
    /\ L2) 
    \/  
    {p2})) by
    A63;
    
              end;
    
                suppose
    
                
    
    A66: p1 
    <> p00; 
    
                now
    
                  assume p00
    in (( 
    LSeg (p1,p2)) 
    /\ L3); 
    
                  then p00
    in ( 
    LSeg (p1,p2)) by 
    XBOOLE_0:def 4;
    
                  then (p1
    `2 ) 
    <= (p00 
    `2 ) by 
    A15,
    A22,
    A27,
    TOPREAL1: 4;
    
                  then (p00
    `2 ) 
    = (p1 
    `2 ) by 
    A3,
    Lm5,
    Lm7,
    TOPREAL1: 4;
    
                  hence contradiction by
    A15,
    A16,
    A66,
    Lm5,
    EUCLID: 53;
    
                end;
    
                then ((
    LSeg (p1,p2)) 
    /\ L3) 
    <>  
    {p00} by
    ZFMISC_1: 31;
    
                then ((
    LSeg (p1,p2)) 
    /\ L3) 
    =  
    {} by 
    A44,
    ZFMISC_1: 33;
    
                hence (P1
    /\ P2) 
    = ( 
    {p1}
    \/ ((( 
    LSeg (p1,p2)) 
    /\ L2) 
    \/  
    {p2})) by
    A63;
    
              end;
    
            end;
    
            
    
            
    
    A67: (( 
    LSeg (p1,p2)) 
    /\ L2) 
    c=  
    {p01} by
    A3,
    A19,
    TOPREAL1: 6,
    TOPREAL1: 15,
    XBOOLE_1: 26;
    
            now
    
              per cases ;
    
                suppose
    
                
    
    A68: p2 
    <> p01; 
    
                now
    
                  assume p01
    in (( 
    LSeg (p1,p2)) 
    /\ L2); 
    
                  then p01
    in ( 
    LSeg (p1,p2)) by 
    XBOOLE_0:def 4;
    
                  then
    
                  
    
    A69: (p01 
    `2 ) 
    <= (p2 
    `2 ) by 
    A15,
    A22,
    A27,
    TOPREAL1: 4;
    
                  (p2
    `2 ) 
    <= (p01 
    `2 ) by 
    A19,
    Lm5,
    Lm7,
    TOPREAL1: 4;
    
                  then
    
                  
    
    A70: (p01 
    `2 ) 
    = (p2 
    `2 ) by 
    A69,
    XXREAL_0: 1;
    
                  p2
    =  
    |[(p2
    `1 ), (p2 
    `2 )]| by 
    EUCLID: 53
    
                  .=
    |[
    0 , 1]| by 
    A22,
    A23,
    A70,
    EUCLID: 52;
    
                  hence contradiction by
    A68;
    
                end;
    
                then ((
    LSeg (p1,p2)) 
    /\ L2) 
    <>  
    {p01} by
    ZFMISC_1: 31;
    
                then ((
    LSeg (p1,p2)) 
    /\ L2) 
    =  
    {} by 
    A67,
    ZFMISC_1: 33;
    
                hence (P1
    /\ P2) 
    =  
    {p1, p2} by
    A64,
    ENUMSET1: 1;
    
              end;
    
                suppose
    
                
    
    A71: p2 
    = p01; 
    
                then p01
    in ( 
    LSeg (p1,p2)) by 
    RLTOPSP1: 68;
    
                then ((
    LSeg (p1,p2)) 
    /\ L2) 
    <>  
    {} by 
    Lm23,
    XBOOLE_0:def 4;
    
                then ((
    LSeg (p1,p2)) 
    /\ L2) 
    =  
    {p2} by
    A67,
    A71,
    ZFMISC_1: 33;
    
                hence (P1
    /\ P2) 
    =  
    {p1, p2} by
    A64,
    ENUMSET1: 1;
    
              end;
    
            end;
    
            hence (P1
    /\ P2) 
    =  
    {p1, p2};
    
          end;
    
            case
    
            
    
    A72: (p 
    `2 ) 
    > (q 
    `2 ); 
    
            
    
            
    
    A73: (( 
    LSeg (p2,p1)) 
    /\ ( 
    LSeg (p01,p1))) 
    c=  
    {p1}
    
            proof
    
              let a be
    object;
    
              assume
    
              
    
    A74: a 
    in (( 
    LSeg (p2,p1)) 
    /\ ( 
    LSeg (p01,p1))); 
    
              then
    
              reconsider p = a as
    Point of ( 
    TOP-REAL 2); 
    
              
    
              
    
    A75: p 
    in ( 
    LSeg (p1,p01)) by 
    A74,
    XBOOLE_0:def 4;
    
              (p1
    `2 ) 
    <= (p01 
    `2 ) by 
    A15,
    A17,
    EUCLID: 52;
    
              then
    
              
    
    A76: (p1 
    `2 ) 
    <= (p 
    `2 ) by 
    A75,
    TOPREAL1: 4;
    
              
    
              
    
    A77: p 
    in ( 
    LSeg (p2,p1)) by 
    A74,
    XBOOLE_0:def 4;
    
              then (p
    `2 ) 
    <= (p1 
    `2 ) by 
    A15,
    A22,
    A72,
    TOPREAL1: 4;
    
              then
    
              
    
    A78: (p1 
    `2 ) 
    = (p 
    `2 ) by 
    A76,
    XXREAL_0: 1;
    
              (p2
    `1 ) 
    <= (p 
    `1 ) by 
    A15,
    A16,
    A22,
    A23,
    A77,
    TOPREAL1: 3;
    
              then (p
    `1 ) 
    =  
    0 by 
    A15,
    A16,
    A22,
    A23,
    A77,
    TOPREAL1: 3;
    
              
    
              then p
    =  
    |[
    0 , (p1 
    `2 )]| by 
    A78,
    EUCLID: 53
    
              .= p1 by
    A15,
    A16,
    EUCLID: 53;
    
              hence thesis by
    TARSKI:def 1;
    
            end;
    
            
    
            
    
    A79: ( 
    LSeg (p2,p00)) 
    c= L1 by 
    A19,
    Lm20,
    TOPREAL1: 6;
    
            
    
    A80: 
    
            now
    
              set a = the
    Element of (( 
    LSeg (p2,p00)) 
    /\ ( 
    LSeg (p01,p1))); 
    
              assume
    
              
    
    A81: (( 
    LSeg (p2,p00)) 
    /\ ( 
    LSeg (p01,p1))) 
    <>  
    {} ; 
    
              then
    
              reconsider p = a as
    Point of ( 
    TOP-REAL 2) by 
    TARSKI:def 3;
    
              
    
              
    
    A82: p 
    in ( 
    LSeg (p00,p2)) by 
    A81,
    XBOOLE_0:def 4;
    
              
    
              
    
    A83: p 
    in ( 
    LSeg (p1,p01)) by 
    A81,
    XBOOLE_0:def 4;
    
              (p1
    `2 ) 
    <= (p01 
    `2 ) by 
    A15,
    A17,
    EUCLID: 52;
    
              then
    
              
    
    A84: (p1 
    `2 ) 
    <= (p 
    `2 ) by 
    A83,
    TOPREAL1: 4;
    
              (p00
    `2 ) 
    <= (p2 
    `2 ) by 
    A22,
    A25,
    EUCLID: 52;
    
              then (p
    `2 ) 
    <= (p2 
    `2 ) by 
    A82,
    TOPREAL1: 4;
    
              hence contradiction by
    A15,
    A22,
    A72,
    A84,
    XXREAL_0: 2;
    
            end;
    
            
    
            
    
    A85: (( 
    LSeg (p2,p1)) 
    /\ L3) 
    c=  
    {p00} by
    A3,
    A19,
    TOPREAL1: 6,
    TOPREAL1: 17,
    XBOOLE_1: 26;
    
            now
    
              assume p01
    in (( 
    LSeg (p2,p00)) 
    /\ L2); 
    
              then
    
              
    
    A86: p01 
    in ( 
    LSeg (p00,p2)) by 
    XBOOLE_0:def 4;
    
              (p00
    `2 ) 
    <= (p2 
    `2 ) by 
    A22,
    A25,
    EUCLID: 52;
    
              then (p01
    `2 ) 
    <= (p2 
    `2 ) by 
    A86,
    TOPREAL1: 4;
    
              hence contradiction by
    A17,
    A22,
    A24,
    A72,
    Lm7,
    XXREAL_0: 1;
    
            end;
    
            then
    
            
    
    A87: 
    {p01}
    <> (( 
    LSeg (p2,p00)) 
    /\ L2) by 
    ZFMISC_1: 31;
    
            
    
            
    
    A88: (( 
    LSeg (p2,p00)) 
    /\ L3) 
    c=  
    {p00} by
    A19,
    Lm20,
    TOPREAL1: 6,
    TOPREAL1: 17,
    XBOOLE_1: 26;
    
            now
    
              assume p00
    in (( 
    LSeg (p01,p1)) 
    /\ L3); 
    
              then
    
              
    
    A89: p00 
    in ( 
    LSeg (p1,p01)) by 
    XBOOLE_0:def 4;
    
              (p1
    `2 ) 
    <= (p01 
    `2 ) by 
    A15,
    A17,
    EUCLID: 52;
    
              hence contradiction by
    A15,
    A25,
    A72,
    A89,
    Lm5,
    TOPREAL1: 4;
    
            end;
    
            then
    
            
    
    A90: 
    {p00}
    <> (( 
    LSeg (p01,p1)) 
    /\ L3) by 
    ZFMISC_1: 31;
    
            
    
            
    
    A91: (( 
    LSeg (p2,p00)) 
    /\ L2) 
    c=  
    {p01} by
    A19,
    Lm20,
    TOPREAL1: 6,
    TOPREAL1: 15,
    XBOOLE_1: 26;
    
            
    
            
    
    A92: (( 
    LSeg (p2,p1)) 
    /\ ( 
    LSeg (p2,p00))) 
    c=  
    {p2}
    
            proof
    
              let a be
    object;
    
              assume
    
              
    
    A93: a 
    in (( 
    LSeg (p2,p1)) 
    /\ ( 
    LSeg (p2,p00))); 
    
              then
    
              reconsider p = a as
    Point of ( 
    TOP-REAL 2); 
    
              
    
              
    
    A94: p 
    in ( 
    LSeg (p00,p2)) by 
    A93,
    XBOOLE_0:def 4;
    
              (p00
    `2 ) 
    <= (p2 
    `2 ) by 
    A22,
    A25,
    EUCLID: 52;
    
              then
    
              
    
    A95: (p 
    `2 ) 
    <= (p2 
    `2 ) by 
    A94,
    TOPREAL1: 4;
    
              
    
              
    
    A96: p 
    in ( 
    LSeg (p2,p1)) by 
    A93,
    XBOOLE_0:def 4;
    
              then (p2
    `2 ) 
    <= (p 
    `2 ) by 
    A15,
    A22,
    A72,
    TOPREAL1: 4;
    
              then
    
              
    
    A97: (p2 
    `2 ) 
    = (p 
    `2 ) by 
    A95,
    XXREAL_0: 1;
    
              (p2
    `1 ) 
    <= (p 
    `1 ) by 
    A15,
    A16,
    A22,
    A23,
    A96,
    TOPREAL1: 3;
    
              then (p
    `1 ) 
    =  
    0 by 
    A15,
    A16,
    A22,
    A23,
    A96,
    TOPREAL1: 3;
    
              
    
              then p
    =  
    |[
    0 , (p2 
    `2 )]| by 
    A97,
    EUCLID: 53
    
              .= p2 by
    A22,
    A23,
    EUCLID: 53;
    
              hence thesis by
    TARSKI:def 1;
    
            end;
    
            
    
            
    
    A98: (( 
    LSeg (p01,p1)) 
    /\ L3) 
    c=  
    {p00} by
    A3,
    Lm22,
    TOPREAL1: 6,
    TOPREAL1: 17,
    XBOOLE_1: 26;
    
            take P1 = (
    LSeg (p2,p1)), P2 = (( 
    LSeg (p2,p00)) 
    \/ (((L3 
    \/ L4) 
    \/ ( 
    LSeg (p11,p01))) 
    \/ ( 
    LSeg (p01,p1)))); 
    
            
    
            
    
    A99: p2 
    in ( 
    LSeg (p2,p00)) by 
    RLTOPSP1: 68;
    
            p2
    in ( 
    LSeg (p2,p1)) by 
    RLTOPSP1: 68;
    
            then p2
    in (( 
    LSeg (p2,p1)) 
    /\ ( 
    LSeg (p2,p00))) by 
    A99,
    XBOOLE_0:def 4;
    
            then
    
            
    
    A100: 
    {p2}
    c= (( 
    LSeg (p2,p1)) 
    /\ ( 
    LSeg (p2,p00))) by 
    ZFMISC_1: 31;
    
            thus P1
    is_an_arc_of (p1,p2) by 
    A1,
    TOPREAL1: 9;
    
            
    
            
    
    A101: (L2 
    /\ (L3 
    \/ L4)) 
    = ( 
    {}  
    \/  
    {p11}) by
    Lm2,
    TOPREAL1: 18,
    XBOOLE_1: 23
    
            .=
    {p11};
    
            (L3
    \/ L4) 
    is_an_arc_of (p11,p00) by 
    Lm4,
    Lm8,
    TOPREAL1: 12,
    TOPREAL1: 16;
    
            then
    
            
    
    A102: ((L3 
    \/ L4) 
    \/ ( 
    LSeg (p11,p01))) 
    is_an_arc_of (p01,p00) by 
    A101,
    TOPREAL1: 11;
    
            p00
    in ( 
    LSeg (p2,p00)) by 
    RLTOPSP1: 68;
    
            then p00
    in (( 
    LSeg (p2,p00)) 
    /\ L3) by 
    Lm21,
    XBOOLE_0:def 4;
    
            then
    
            
    
    A103: 
    {p00}
    c= (( 
    LSeg (p2,p00)) 
    /\ L3) by 
    ZFMISC_1: 31;
    
            ((
    LSeg (p1,p01)) 
    /\ ((L3 
    \/ L4) 
    \/ ( 
    LSeg (p11,p01)))) 
    = ((( 
    LSeg (p01,p1)) 
    /\ (L3 
    \/ L4)) 
    \/ (( 
    LSeg (p01,p1)) 
    /\ ( 
    LSeg (p11,p01)))) by 
    XBOOLE_1: 23
    
            .= ((((
    LSeg (p01,p1)) 
    /\ L3) 
    \/ (( 
    LSeg (p01,p1)) 
    /\ L4)) 
    \/ (( 
    LSeg (p01,p1)) 
    /\ ( 
    LSeg (p11,p01)))) by 
    XBOOLE_1: 23
    
            .= ((
    {}  
    \/ (( 
    LSeg (p01,p1)) 
    /\ L4)) 
    \/ (( 
    LSeg (p01,p1)) 
    /\ ( 
    LSeg (p11,p01)))) by 
    A98,
    A90,
    ZFMISC_1: 33
    
            .=
    {p01} by
    A14,
    A10,
    A12,
    XBOOLE_0:def 10;
    
            then
    
            
    
    A104: (((L3 
    \/ L4) 
    \/ ( 
    LSeg (p11,p01))) 
    \/ ( 
    LSeg (p01,p1))) 
    is_an_arc_of (p1,p00) by 
    A102,
    TOPREAL1: 11;
    
            ((((L3
    \/ L4) 
    \/ ( 
    LSeg (p11,p01))) 
    \/ ( 
    LSeg (p01,p1))) 
    /\ ( 
    LSeg (p00,p2))) 
    = ((( 
    LSeg (p2,p00)) 
    /\ ((L3 
    \/ L4) 
    \/ ( 
    LSeg (p11,p01)))) 
    \/ (( 
    LSeg (p2,p00)) 
    /\ ( 
    LSeg (p01,p1)))) by 
    XBOOLE_1: 23
    
            .= ((((
    LSeg (p2,p00)) 
    /\ (L3 
    \/ L4)) 
    \/ (( 
    LSeg (p2,p00)) 
    /\ ( 
    LSeg (p11,p01)))) 
    \/ (( 
    LSeg (p2,p00)) 
    /\ ( 
    LSeg (p01,p1)))) by 
    XBOOLE_1: 23
    
            .= (((((
    LSeg (p2,p00)) 
    /\ L3) 
    \/ (( 
    LSeg (p2,p00)) 
    /\ L4)) 
    \/ (( 
    LSeg (p2,p00)) 
    /\ ( 
    LSeg (p11,p01)))) 
    \/ (( 
    LSeg (p2,p00)) 
    /\ ( 
    LSeg (p01,p1)))) by 
    XBOOLE_1: 23
    
            .= (((((
    LSeg (p2,p00)) 
    /\ L3) 
    \/  
    {} ) 
    \/ (( 
    LSeg (p2,p00)) 
    /\ ( 
    LSeg (p11,p01)))) 
    \/ (( 
    LSeg (p2,p00)) 
    /\ ( 
    LSeg (p01,p1)))) by 
    A79,
    Lm3,
    XBOOLE_1: 3,
    XBOOLE_1: 26
    
            .= (((
    LSeg (p2,p00)) 
    /\ L3) 
    \/  
    {} ) by 
    A80,
    A91,
    A87,
    ZFMISC_1: 33
    
            .=
    {p00} by
    A103,
    A88,
    XBOOLE_0:def 10;
    
            hence P2
    is_an_arc_of (p1,p2) by 
    A104,
    TOPREAL1: 10;
    
            (((
    LSeg (p01,p1)) 
    \/ ( 
    LSeg (p1,p2))) 
    \/ ( 
    LSeg (p2,p00))) 
    = L1 by 
    A3,
    A19,
    TOPREAL1: 7;
    
            
    
            hence
    R^2-unit_square  
    = (((( 
    LSeg (p2,p1)) 
    \/ ( 
    LSeg (p01,p1))) 
    \/ ( 
    LSeg (p2,p00))) 
    \/ ((L3 
    \/ L4) 
    \/ ( 
    LSeg (p11,p01)))) by 
    TOPREAL1:def 2,
    XBOOLE_1: 4
    
            .= (((
    LSeg (p2,p1)) 
    \/ (( 
    LSeg (p2,p00)) 
    \/ ( 
    LSeg (p01,p1)))) 
    \/ ((L3 
    \/ L4) 
    \/ ( 
    LSeg (p11,p01)))) by 
    XBOOLE_1: 4
    
            .= ((
    LSeg (p2,p1)) 
    \/ ((( 
    LSeg (p2,p00)) 
    \/ ( 
    LSeg (p01,p1))) 
    \/ ((L3 
    \/ L4) 
    \/ ( 
    LSeg (p11,p01))))) by 
    XBOOLE_1: 4
    
            .= (P1
    \/ P2) by 
    XBOOLE_1: 4;
    
            
    
            
    
    A105: p1 
    in ( 
    LSeg (p01,p1)) by 
    RLTOPSP1: 68;
    
            p1
    in ( 
    LSeg (p2,p1)) by 
    RLTOPSP1: 68;
    
            then p1
    in (( 
    LSeg (p2,p1)) 
    /\ ( 
    LSeg (p01,p1))) by 
    A105,
    XBOOLE_0:def 4;
    
            then
    
            
    
    A106: 
    {p1}
    c= (( 
    LSeg (p2,p1)) 
    /\ ( 
    LSeg (p01,p1))) by 
    ZFMISC_1: 31;
    
            
    
            
    
    A107: (P1 
    /\ P2) 
    = ((( 
    LSeg (p2,p1)) 
    /\ ( 
    LSeg (p2,p00))) 
    \/ (( 
    LSeg (p2,p1)) 
    /\ (((L3 
    \/ L4) 
    \/ ( 
    LSeg (p11,p01))) 
    \/ ( 
    LSeg (p01,p1))))) by 
    XBOOLE_1: 23
    
            .= (((
    LSeg (p2,p1)) 
    /\ ( 
    LSeg (p2,p00))) 
    \/ ((( 
    LSeg (p2,p1)) 
    /\ ((L3 
    \/ L4) 
    \/ ( 
    LSeg (p11,p01)))) 
    \/ (( 
    LSeg (p2,p1)) 
    /\ ( 
    LSeg (p01,p1))))) by 
    XBOOLE_1: 23
    
            .= (((
    LSeg (p2,p1)) 
    /\ ( 
    LSeg (p2,p00))) 
    \/ (((( 
    LSeg (p2,p1)) 
    /\ (L3 
    \/ L4)) 
    \/ (( 
    LSeg (p2,p1)) 
    /\ ( 
    LSeg (p11,p01)))) 
    \/ (( 
    LSeg (p2,p1)) 
    /\ ( 
    LSeg (p01,p1))))) by 
    XBOOLE_1: 23
    
            .= (((
    LSeg (p2,p1)) 
    /\ ( 
    LSeg (p2,p00))) 
    \/ ((((( 
    LSeg (p2,p1)) 
    /\ L3) 
    \/ (( 
    LSeg (p2,p1)) 
    /\ L4)) 
    \/ (( 
    LSeg (p2,p1)) 
    /\ ( 
    LSeg (p11,p01)))) 
    \/ (( 
    LSeg (p2,p1)) 
    /\ ( 
    LSeg (p01,p1))))) by 
    XBOOLE_1: 23
    
            .= (
    {p2}
    \/ ((((( 
    LSeg (p2,p1)) 
    /\ L3) 
    \/ (( 
    LSeg (p2,p1)) 
    /\ L4)) 
    \/ (( 
    LSeg (p2,p1)) 
    /\ ( 
    LSeg (p11,p01)))) 
    \/ (( 
    LSeg (p2,p1)) 
    /\ ( 
    LSeg (p01,p1))))) by 
    A100,
    A92,
    XBOOLE_0:def 10
    
            .= (
    {p2}
    \/ ((((( 
    LSeg (p2,p1)) 
    /\ L3) 
    \/  
    {} ) 
    \/ (( 
    LSeg (p2,p1)) 
    /\ ( 
    LSeg (p11,p01)))) 
    \/ (( 
    LSeg (p2,p1)) 
    /\ ( 
    LSeg (p01,p1))))) by 
    A20,
    Lm3,
    XBOOLE_1: 3,
    XBOOLE_1: 26
    
            .= (
    {p2}
    \/ (((( 
    LSeg (p2,p1)) 
    /\ L3) 
    \/ (( 
    LSeg (p2,p1)) 
    /\ L2)) 
    \/  
    {p1})) by
    A106,
    A73,
    XBOOLE_0:def 10
    
            .= (
    {p2}
    \/ ((( 
    LSeg (p2,p1)) 
    /\ L3) 
    \/ ((( 
    LSeg (p2,p1)) 
    /\ L2) 
    \/  
    {p1}))) by
    XBOOLE_1: 4
    
            .= ((
    {p2}
    \/ (( 
    LSeg (p2,p1)) 
    /\ L3)) 
    \/ ((( 
    LSeg (p2,p1)) 
    /\ L2) 
    \/  
    {p1})) by
    XBOOLE_1: 4;
    
            
    
    A108: 
    
            now
    
              per cases ;
    
                suppose
    
                
    
    A109: p2 
    = p00; 
    
                p2
    in ( 
    LSeg (p2,p1)) by 
    RLTOPSP1: 68;
    
                then ((
    LSeg (p2,p1)) 
    /\ L3) 
    <>  
    {} by 
    A109,
    Lm21,
    XBOOLE_0:def 4;
    
                then ((
    LSeg (p2,p1)) 
    /\ L3) 
    =  
    {p2} by
    A85,
    A109,
    ZFMISC_1: 33;
    
                hence (P1
    /\ P2) 
    = ( 
    {p2}
    \/ ((( 
    LSeg (p2,p1)) 
    /\ L2) 
    \/  
    {p1})) by
    A107;
    
              end;
    
                suppose
    
                
    
    A110: p2 
    <> p00; 
    
                now
    
                  assume p00
    in (( 
    LSeg (p2,p1)) 
    /\ L3); 
    
                  then p00
    in ( 
    LSeg (p2,p1)) by 
    XBOOLE_0:def 4;
    
                  then (p2
    `2 ) 
    <= (p00 
    `2 ) by 
    A15,
    A22,
    A72,
    TOPREAL1: 4;
    
                  then (p00
    `2 ) 
    = (p2 
    `2 ) by 
    A19,
    Lm5,
    Lm7,
    TOPREAL1: 4;
    
                  hence contradiction by
    A22,
    A23,
    A110,
    Lm5,
    EUCLID: 53;
    
                end;
    
                then ((
    LSeg (p2,p1)) 
    /\ L3) 
    <>  
    {p00} by
    ZFMISC_1: 31;
    
                then ((
    LSeg (p2,p1)) 
    /\ L3) 
    =  
    {} by 
    A85,
    ZFMISC_1: 33;
    
                hence (P1
    /\ P2) 
    = ( 
    {p2}
    \/ ((( 
    LSeg (p2,p1)) 
    /\ L2) 
    \/  
    {p1})) by
    A107;
    
              end;
    
            end;
    
            
    
            
    
    A111: (( 
    LSeg (p2,p1)) 
    /\ L2) 
    c=  
    {p01} by
    A3,
    A19,
    TOPREAL1: 6,
    TOPREAL1: 15,
    XBOOLE_1: 26;
    
            now
    
              per cases ;
    
                suppose
    
                
    
    A112: p1 
    <> p01; 
    
                now
    
                  assume p01
    in (( 
    LSeg (p2,p1)) 
    /\ L2); 
    
                  then p01
    in ( 
    LSeg (p2,p1)) by 
    XBOOLE_0:def 4;
    
                  then
    
                  
    
    A113: (p01 
    `2 ) 
    <= (p1 
    `2 ) by 
    A15,
    A22,
    A72,
    TOPREAL1: 4;
    
                  (p1
    `2 ) 
    <= (p01 
    `2 ) by 
    A3,
    Lm5,
    Lm7,
    TOPREAL1: 4;
    
                  then
    
                  
    
    A114: (p01 
    `2 ) 
    = (p1 
    `2 ) by 
    A113,
    XXREAL_0: 1;
    
                  p1
    =  
    |[(p1
    `1 ), (p1 
    `2 )]| by 
    EUCLID: 53
    
                  .=
    |[
    0 , 1]| by 
    A15,
    A16,
    A114,
    EUCLID: 52;
    
                  hence contradiction by
    A112;
    
                end;
    
                then ((
    LSeg (p2,p1)) 
    /\ L2) 
    <>  
    {p01} by
    ZFMISC_1: 31;
    
                then ((
    LSeg (p2,p1)) 
    /\ L2) 
    =  
    {} by 
    A111,
    ZFMISC_1: 33;
    
                hence (P1
    /\ P2) 
    =  
    {p1, p2} by
    A108,
    ENUMSET1: 1;
    
              end;
    
                suppose
    
                
    
    A115: p1 
    = p01; 
    
                then p01
    in ( 
    LSeg (p2,p1)) by 
    RLTOPSP1: 68;
    
                then ((
    LSeg (p2,p1)) 
    /\ L2) 
    <>  
    {} by 
    Lm23,
    XBOOLE_0:def 4;
    
                then ((
    LSeg (p2,p1)) 
    /\ L2) 
    =  
    {p1} by
    A111,
    A115,
    ZFMISC_1: 33;
    
                hence (P1
    /\ P2) 
    =  
    {p1, p2} by
    A108,
    ENUMSET1: 1;
    
              end;
    
            end;
    
            hence (P1
    /\ P2) 
    =  
    {p1, p2};
    
          end;
    
        end;
    
        hence thesis;
    
      end;
    
        suppose
    
        
    
    A116: p2 
    in L2; 
    
        then
    
        
    
    A117: ( 
    LSeg (p01,p2)) 
    c= L2 by 
    Lm23,
    TOPREAL1: 6;
    
        (
    LSeg (p1,p01)) 
    c= L1 by 
    A3,
    Lm22,
    TOPREAL1: 6;
    
        then
    
        
    
    A118: (( 
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p01,p2))) 
    c= (L1 
    /\ L2) by 
    A117,
    XBOOLE_1: 27;
    
        take P1 = ((
    LSeg (p1,p01)) 
    \/ ( 
    LSeg (p01,p2))), P2 = (( 
    LSeg (p1,p00)) 
    \/ ((L3 
    \/ L4) 
    \/ ( 
    LSeg (p11,p2)))); 
    
        
    
        
    
    A119: p01 
    in ( 
    LSeg (p01,p2)) by 
    RLTOPSP1: 68;
    
        p11
    in ( 
    LSeg (p11,p2)) by 
    RLTOPSP1: 68;
    
        then
    
        
    
    A120: p11 
    in (L4 
    /\ ( 
    LSeg (p11,p2))) by 
    Lm27,
    XBOOLE_0:def 4;
    
        p01
    in ( 
    LSeg (p1,p01)) by 
    RLTOPSP1: 68;
    
        then ((
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p01,p2))) 
    <>  
    {} by 
    A119,
    XBOOLE_0:def 4;
    
        then
    
        
    
    A121: (( 
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p01,p2))) 
    =  
    {p01} by
    A118,
    TOPREAL1: 15,
    ZFMISC_1: 33;
    
        p1
    <> p01 or p2 
    <> p01 by 
    A1;
    
        hence P1
    is_an_arc_of (p1,p2) by 
    A121,
    TOPREAL1: 12;
    
        
    
        
    
    A122: L1 
    = (( 
    LSeg (p1,p01)) 
    \/ ( 
    LSeg (p1,p00))) by 
    A3,
    TOPREAL1: 5;
    
        
    
        
    
    A123: L4 
    is_an_arc_of (p10,p11) by 
    Lm9,
    Lm11,
    TOPREAL1: 9;
    
        L3
    is_an_arc_of (p00,p10) by 
    Lm4,
    Lm8,
    TOPREAL1: 9;
    
        then
    
        
    
    A124: (L3 
    \/ L4) 
    is_an_arc_of (p00,p11) by 
    A123,
    TOPREAL1: 2,
    TOPREAL1: 16;
    
        
    
        
    
    A125: ( 
    LSeg (p11,p2)) 
    c= L2 by 
    A116,
    Lm26,
    TOPREAL1: 6;
    
        then
    
        
    
    A126: (L4 
    /\ ( 
    LSeg (p11,p2))) 
    c= (L4 
    /\ L2) by 
    XBOOLE_1: 27;
    
        
    
        
    
    A127: (L3 
    /\ ( 
    LSeg (p11,p2))) 
    =  
    {} by 
    A125,
    Lm2,
    XBOOLE_1: 3,
    XBOOLE_1: 26;
    
        ((L3
    \/ L4) 
    /\ ( 
    LSeg (p11,p2))) 
    = ((L3 
    /\ ( 
    LSeg (p11,p2))) 
    \/ (L4 
    /\ ( 
    LSeg (p11,p2)))) by 
    XBOOLE_1: 23
    
        .=
    {p11} by
    A127,
    A126,
    A120,
    TOPREAL1: 18,
    ZFMISC_1: 33;
    
        then
    
        
    
    A128: ((L3 
    \/ L4) 
    \/ ( 
    LSeg (p11,p2))) 
    is_an_arc_of (p00,p2) by 
    A124,
    TOPREAL1: 10;
    
        
    
        
    
    A129: (( 
    LSeg (p01,p2)) 
    /\ ( 
    LSeg (p11,p2))) 
    =  
    {p2} by
    A116,
    TOPREAL1: 8;
    
        
    
        
    
    A130: L2 
    = (( 
    LSeg (p11,p2)) 
    \/ ( 
    LSeg (p01,p2))) by 
    A116,
    TOPREAL1: 5;
    
        ((
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p11,p2))) 
    c=  
    {p01} by
    A4,
    A125,
    TOPREAL1: 15,
    XBOOLE_1: 27;
    
        then
    
        
    
    A131: (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p11,p2))) 
    =  
    {p01} or ((
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p11,p2))) 
    =  
    {} by 
    ZFMISC_1: 33;
    
        
    
        
    
    A132: ( 
    LSeg (p01,p2)) 
    c= L2 by 
    A116,
    Lm23,
    TOPREAL1: 6;
    
        then
    
        
    
    A133: (( 
    LSeg (p01,p2)) 
    /\ L3) 
    =  
    {} by 
    Lm2,
    XBOOLE_1: 3,
    XBOOLE_1: 27;
    
        
    
        
    
    A134: ex q st q 
    = p2 & (q 
    `1 ) 
    <= 1 & (q 
    `1 ) 
    >=  
    0 & (q 
    `2 ) 
    = 1 by 
    A116,
    TOPREAL1: 13;
    
        
    
    A135: 
    
        now
    
          
    
          
    
    A136: (p2 
    `1 ) 
    <= (p11 
    `1 ) by 
    A134,
    EUCLID: 52;
    
          assume
    
          
    
    A137: p01 
    in (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p11,p2))); 
    
          then
    
          
    
    A138: p01 
    in ( 
    LSeg (p00,p1)) by 
    XBOOLE_0:def 4;
    
          p01
    in ( 
    LSeg (p2,p11)) by 
    A137,
    XBOOLE_0:def 4;
    
          then
    
          
    
    A139: (p01 
    `1 ) 
    = (p2 
    `1 ) by 
    A134,
    A136,
    Lm6,
    TOPREAL1: 3;
    
          (p00
    `2 ) 
    <= (p1 
    `2 ) by 
    A15,
    A18,
    EUCLID: 52;
    
          then (p01
    `2 ) 
    <= (p1 
    `2 ) by 
    A138,
    TOPREAL1: 4;
    
          then (p01
    `2 ) 
    = (p1 
    `2 ) by 
    A15,
    A17,
    Lm7,
    XXREAL_0: 1;
    
          
    
          then p1
    =  
    |[(p01
    `1 ), (p01 
    `2 )]| by 
    A15,
    A16,
    Lm6,
    EUCLID: 53
    
          .= p2 by
    A134,
    A139,
    Lm7,
    EUCLID: 53;
    
          hence contradiction by
    A1;
    
        end;
    
        ((
    LSeg (p1,p00)) 
    /\ ((L3 
    \/ L4) 
    \/ ( 
    LSeg (p11,p2)))) 
    = ((( 
    LSeg (p1,p00)) 
    /\ (L3 
    \/ L4)) 
    \/ (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p11,p2)))) by 
    XBOOLE_1: 23
    
        .= (((
    LSeg (p1,p00)) 
    /\ L3) 
    \/ (( 
    LSeg (p1,p00)) 
    /\ L4)) by 
    A131,
    A135,
    XBOOLE_1: 23,
    ZFMISC_1: 31
    
        .=
    {p00} by
    A9,
    A5,
    A6,
    TOPREAL1: 17,
    XBOOLE_0:def 10;
    
        hence P2
    is_an_arc_of (p1,p2) by 
    A128,
    TOPREAL1: 11;
    
        
    
        thus (P1
    \/ P2) 
    = (( 
    LSeg (p01,p2)) 
    \/ (( 
    LSeg (p1,p01)) 
    \/ (( 
    LSeg (p1,p00)) 
    \/ ((L3 
    \/ L4) 
    \/ ( 
    LSeg (p11,p2)))))) by 
    XBOOLE_1: 4
    
        .= ((L1
    \/ ((L3 
    \/ L4) 
    \/ ( 
    LSeg (p11,p2)))) 
    \/ ( 
    LSeg (p01,p2))) by 
    A122,
    XBOOLE_1: 4
    
        .= (L1
    \/ (((L3 
    \/ L4) 
    \/ ( 
    LSeg (p11,p2))) 
    \/ ( 
    LSeg (p01,p2)))) by 
    XBOOLE_1: 4
    
        .= (L1
    \/ (L2 
    \/ (L3 
    \/ L4))) by 
    A130,
    XBOOLE_1: 4
    
        .=
    R^2-unit_square by 
    TOPREAL1:def 2,
    XBOOLE_1: 4;
    
        
    
        
    
    A140: 
    {p1}
    = (( 
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p1,p00))) by 
    A3,
    TOPREAL1: 8;
    
        
    
        
    
    A141: (P1 
    /\ P2) 
    = ((( 
    LSeg (p1,p01)) 
    /\ (( 
    LSeg (p1,p00)) 
    \/ ((L3 
    \/ L4) 
    \/ ( 
    LSeg (p11,p2))))) 
    \/ (( 
    LSeg (p01,p2)) 
    /\ (( 
    LSeg (p1,p00)) 
    \/ ((L3 
    \/ L4) 
    \/ ( 
    LSeg (p11,p2)))))) by 
    XBOOLE_1: 23
    
        .= ((((
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p1,p00))) 
    \/ (( 
    LSeg (p1,p01)) 
    /\ ((L3 
    \/ L4) 
    \/ ( 
    LSeg (p11,p2))))) 
    \/ (( 
    LSeg (p01,p2)) 
    /\ (( 
    LSeg (p1,p00)) 
    \/ ((L3 
    \/ L4) 
    \/ ( 
    LSeg (p11,p2)))))) by 
    XBOOLE_1: 23
    
        .= ((
    {p1}
    \/ ((( 
    LSeg (p1,p01)) 
    /\ (L3 
    \/ L4)) 
    \/ (( 
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p11,p2))))) 
    \/ (( 
    LSeg (p01,p2)) 
    /\ (( 
    LSeg (p1,p00)) 
    \/ ((L3 
    \/ L4) 
    \/ ( 
    LSeg (p11,p2)))))) by 
    A140,
    XBOOLE_1: 23
    
        .= ((
    {p1}
    \/ (((( 
    LSeg (p1,p01)) 
    /\ L3) 
    \/ (( 
    LSeg (p1,p01)) 
    /\ L4)) 
    \/ (( 
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p11,p2))))) 
    \/ (( 
    LSeg (p01,p2)) 
    /\ (( 
    LSeg (p1,p00)) 
    \/ ((L3 
    \/ L4) 
    \/ ( 
    LSeg (p11,p2)))))) by 
    XBOOLE_1: 23
    
        .= ((
    {p1}
    \/ (((( 
    LSeg (p1,p01)) 
    /\ L3) 
    \/ (( 
    LSeg (p1,p01)) 
    /\ L4)) 
    \/ (( 
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p11,p2))))) 
    \/ ((( 
    LSeg (p01,p2)) 
    /\ ( 
    LSeg (p1,p00))) 
    \/ (( 
    LSeg (p01,p2)) 
    /\ ((L3 
    \/ L4) 
    \/ ( 
    LSeg (p11,p2)))))) by 
    XBOOLE_1: 23
    
        .= ((
    {p1}
    \/ (((( 
    LSeg (p1,p01)) 
    /\ L3) 
    \/ (( 
    LSeg (p1,p01)) 
    /\ L4)) 
    \/ (( 
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p11,p2))))) 
    \/ ((( 
    LSeg (p01,p2)) 
    /\ ( 
    LSeg (p1,p00))) 
    \/ ((( 
    LSeg (p01,p2)) 
    /\ (L3 
    \/ L4)) 
    \/  
    {p2}))) by
    A129,
    XBOOLE_1: 23
    
        .= ((
    {p1}
    \/ (((( 
    LSeg (p1,p01)) 
    /\ L3) 
    \/ (( 
    LSeg (p1,p01)) 
    /\ L4)) 
    \/ (( 
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p11,p2))))) 
    \/ ((( 
    LSeg (p01,p2)) 
    /\ ( 
    LSeg (p1,p00))) 
    \/ (((( 
    LSeg (p01,p2)) 
    /\ L3) 
    \/ (( 
    LSeg (p01,p2)) 
    /\ L4)) 
    \/  
    {p2}))) by
    XBOOLE_1: 23
    
        .= ((
    {p1}
    \/ ((( 
    LSeg (p1,p01)) 
    /\ L3) 
    \/ (( 
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p11,p2))))) 
    \/ ((( 
    LSeg (p01,p2)) 
    /\ ( 
    LSeg (p1,p00))) 
    \/ ((( 
    LSeg (p01,p2)) 
    /\ L4) 
    \/  
    {p2}))) by
    A14,
    A133;
    
        
    
    A142: 
    
        now
    
          per cases ;
    
            suppose
    
            
    
    A143: p2 
    = p11; 
    
            then
    
            
    
    A144: not p2 
    in ( 
    LSeg (p1,p01)) by 
    A13,
    Lm4,
    Lm6,
    Lm10,
    TOPREAL1: 3;
    
            ((
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p11,p2))) 
    = (( 
    LSeg (p1,p01)) 
    /\  
    {p2}) by
    A143,
    RLTOPSP1: 70
    
            .=
    {} by 
    A144,
    Lm1;
    
            hence (P1
    /\ P2) 
    = (( 
    {p1}
    \/ (( 
    LSeg (p1,p01)) 
    /\ L3)) 
    \/ ((( 
    LSeg (p01,p2)) 
    /\ ( 
    LSeg (p1,p00))) 
    \/  
    {p2})) by
    A141,
    A143,
    TOPREAL1: 18;
    
          end;
    
            suppose
    
            
    
    A145: p2 
    <> p11 & p2 
    <> p01; 
    
            now
    
              assume p01
    in (( 
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p11,p2))); 
    
              then
    
              
    
    A146: p01 
    in ( 
    LSeg (p2,p11)) by 
    XBOOLE_0:def 4;
    
              (p2
    `1 ) 
    <= (p11 
    `1 ) by 
    A134,
    EUCLID: 52;
    
              then (p2
    `1 ) 
    =  
    0 by 
    A134,
    A146,
    Lm6,
    TOPREAL1: 3;
    
              hence contradiction by
    A134,
    A145,
    EUCLID: 53;
    
            end;
    
            then
    
            
    
    A147: 
    {p01}
    <> (( 
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p11,p2))) by 
    ZFMISC_1: 31;
    
            ((
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p11,p2))) 
    c=  
    {p01} by
    A13,
    A125,
    TOPREAL1: 15,
    XBOOLE_1: 27;
    
            then
    
            
    
    A148: (( 
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p11,p2))) 
    =  
    {} by 
    A147,
    ZFMISC_1: 33;
    
            now
    
              assume p11
    in (( 
    LSeg (p01,p2)) 
    /\ L4); 
    
              then
    
              
    
    A149: p11 
    in ( 
    LSeg (p01,p2)) by 
    XBOOLE_0:def 4;
    
              (p01
    `1 ) 
    <= (p2 
    `1 ) by 
    A134,
    EUCLID: 52;
    
              then (p11
    `1 ) 
    <= (p2 
    `1 ) by 
    A149,
    TOPREAL1: 3;
    
              then (p2
    `1 ) 
    = (p11 
    `1 ) by 
    A134,
    Lm10,
    XXREAL_0: 1;
    
              hence contradiction by
    A134,
    A145,
    Lm10,
    EUCLID: 53;
    
            end;
    
            then
    
            
    
    A150: 
    {p11}
    <> (( 
    LSeg (p01,p2)) 
    /\ L4) by 
    ZFMISC_1: 31;
    
            ((
    LSeg (p01,p2)) 
    /\ L4) 
    c=  
    {p11} by
    A132,
    TOPREAL1: 18,
    XBOOLE_1: 27;
    
            then ((
    LSeg (p01,p2)) 
    /\ L4) 
    =  
    {} by 
    A150,
    ZFMISC_1: 33;
    
            hence (P1
    /\ P2) 
    = (( 
    {p1}
    \/ (( 
    LSeg (p1,p01)) 
    /\ L3)) 
    \/ ((( 
    LSeg (p01,p2)) 
    /\ ( 
    LSeg (p1,p00))) 
    \/  
    {p2})) by
    A141,
    A148;
    
          end;
    
            suppose
    
            
    
    A151: p2 
    = p01; 
    
            then p2
    in ( 
    LSeg (p1,p01)) by 
    RLTOPSP1: 68;
    
            then
    
            
    
    A152: (( 
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p11,p2))) 
    <>  
    {} by 
    A151,
    Lm23,
    XBOOLE_0:def 4;
    
            ((
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p11,p2))) 
    c=  
    {p2} by
    A13,
    A151,
    TOPREAL1: 15,
    XBOOLE_1: 27;
    
            then
    
            
    
    A153: (( 
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p11,p2))) 
    =  
    {p2} by
    A152,
    ZFMISC_1: 33;
    
            ((
    LSeg (p01,p2)) 
    /\ L4) 
    = ( 
    {p01}
    /\ L4) by 
    A151,
    RLTOPSP1: 70
    
            .=
    {} by 
    Lm1,
    Lm15;
    
            
    
            hence (P1
    /\ P2) 
    = ((( 
    {p1}
    \/ (( 
    LSeg (p1,p01)) 
    /\ L3)) 
    \/  
    {p2})
    \/ ((( 
    LSeg (p01,p2)) 
    /\ ( 
    LSeg (p1,p00))) 
    \/  
    {p2})) by
    A141,
    A153,
    XBOOLE_1: 4
    
            .= ((
    {p1}
    \/ (( 
    LSeg (p1,p01)) 
    /\ L3)) 
    \/ (((( 
    LSeg (p01,p2)) 
    /\ ( 
    LSeg (p1,p00))) 
    \/  
    {p2})
    \/  
    {p2})) by
    XBOOLE_1: 4
    
            .= ((
    {p1}
    \/ (( 
    LSeg (p1,p01)) 
    /\ L3)) 
    \/ ((( 
    LSeg (p01,p2)) 
    /\ ( 
    LSeg (p1,p00))) 
    \/ ( 
    {p2}
    \/  
    {p2}))) by
    XBOOLE_1: 4
    
            .= ((
    {p1}
    \/ (( 
    LSeg (p1,p01)) 
    /\ L3)) 
    \/ ((( 
    LSeg (p01,p2)) 
    /\ ( 
    LSeg (p1,p00))) 
    \/  
    {p2}));
    
          end;
    
        end;
    
        now
    
          per cases ;
    
            suppose
    
            
    
    A154: p1 
    = p01; 
    
            then p1
    in ( 
    LSeg (p01,p2)) by 
    RLTOPSP1: 68;
    
            then
    
            
    
    A155: (( 
    LSeg (p01,p2)) 
    /\ ( 
    LSeg (p1,p00))) 
    <>  
    {} by 
    A154,
    Lm22,
    XBOOLE_0:def 4;
    
            ((
    LSeg (p01,p2)) 
    /\ ( 
    LSeg (p1,p00))) 
    c=  
    {p1} by
    A132,
    A154,
    TOPREAL1: 15,
    XBOOLE_1: 27;
    
            then
    
            
    
    A156: (( 
    LSeg (p01,p2)) 
    /\ ( 
    LSeg (p1,p00))) 
    =  
    {p1} by
    A155,
    ZFMISC_1: 33;
    
            ((
    LSeg (p1,p01)) 
    /\ L3) 
    = ( 
    {p1}
    /\ L3) by 
    A154,
    RLTOPSP1: 70
    
            .=
    {} by 
    A154,
    Lm1,
    Lm14;
    
            
    
            hence (P1
    /\ P2) 
    = (( 
    {p1}
    \/  
    {p1})
    \/  
    {p2}) by
    A142,
    A156,
    XBOOLE_1: 4
    
            .=
    {p1, p2} by
    ENUMSET1: 1;
    
          end;
    
            suppose
    
            
    
    A157: p1 
    = p00; 
    
            
    
            
    
    A158: not p00 
    in ( 
    LSeg (p01,p2)) by 
    A132,
    Lm5,
    Lm7,
    Lm11,
    TOPREAL1: 4;
    
            ((
    LSeg (p01,p2)) 
    /\ ( 
    LSeg (p1,p00))) 
    = (( 
    LSeg (p01,p2)) 
    /\  
    {p00}) by
    A157,
    RLTOPSP1: 70
    
            .=
    {} by 
    A158,
    Lm1;
    
            hence thesis by
    A142,
    A157,
    ENUMSET1: 1,
    TOPREAL1: 17;
    
          end;
    
            suppose
    
            
    
    A159: p1 
    <> p00 & p1 
    <> p01; 
    
            now
    
              assume p01
    in (( 
    LSeg (p01,p2)) 
    /\ ( 
    LSeg (p1,p00))); 
    
              then
    
              
    
    A160: p01 
    in ( 
    LSeg (p00,p1)) by 
    XBOOLE_0:def 4;
    
              (p00
    `2 ) 
    <= (p1 
    `2 ) by 
    A15,
    A18,
    EUCLID: 52;
    
              then (p01
    `2 ) 
    <= (p1 
    `2 ) by 
    A160,
    TOPREAL1: 4;
    
              then (p1
    `2 ) 
    = 1 by 
    A15,
    A17,
    Lm7,
    XXREAL_0: 1;
    
              hence contradiction by
    A15,
    A16,
    A159,
    EUCLID: 53;
    
            end;
    
            then
    
            
    
    A161: 
    {p01}
    <> (( 
    LSeg (p01,p2)) 
    /\ ( 
    LSeg (p1,p00))) by 
    ZFMISC_1: 31;
    
            ((
    LSeg (p01,p2)) 
    /\ ( 
    LSeg (p1,p00))) 
    c=  
    {p01} by
    A4,
    A132,
    TOPREAL1: 15,
    XBOOLE_1: 27;
    
            then
    
            
    
    A162: (( 
    LSeg (p01,p2)) 
    /\ ( 
    LSeg (p1,p00))) 
    =  
    {} by 
    A161,
    ZFMISC_1: 33;
    
            now
    
              assume p00
    in (( 
    LSeg (p1,p01)) 
    /\ L3); 
    
              then
    
              
    
    A163: p00 
    in ( 
    LSeg (p1,p01)) by 
    XBOOLE_0:def 4;
    
              (p1
    `2 ) 
    <= (p01 
    `2 ) by 
    A15,
    A17,
    EUCLID: 52;
    
              then (p1
    `2 ) 
    =  
    0 by 
    A15,
    A18,
    A163,
    Lm5,
    TOPREAL1: 4;
    
              hence contradiction by
    A15,
    A16,
    A159,
    EUCLID: 53;
    
            end;
    
            then
    
            
    
    A164: 
    {p00}
    <> (( 
    LSeg (p1,p01)) 
    /\ L3) by 
    ZFMISC_1: 31;
    
            ((
    LSeg (p1,p01)) 
    /\ L3) 
    c=  
    {p00} by
    A13,
    TOPREAL1: 17,
    XBOOLE_1: 27;
    
            then ((
    LSeg (p1,p01)) 
    /\ L3) 
    =  
    {} by 
    A164,
    ZFMISC_1: 33;
    
            hence thesis by
    A142,
    A162,
    ENUMSET1: 1;
    
          end;
    
        end;
    
        hence thesis;
    
      end;
    
        suppose
    
        
    
    A165: p2 
    in L3; 
    
        then
    
        
    
    A166: ( 
    LSeg (p00,p2)) 
    c= L3 by 
    Lm21,
    TOPREAL1: 6;
    
        (
    LSeg (p1,p00)) 
    c= L1 by 
    A3,
    Lm20,
    TOPREAL1: 6;
    
        then
    
        
    
    A167: (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p00,p2))) 
    c= (L1 
    /\ L3) by 
    A166,
    XBOOLE_1: 27;
    
        take P1 = ((
    LSeg (p1,p00)) 
    \/ ( 
    LSeg (p00,p2))), P2 = (( 
    LSeg (p1,p01)) 
    \/ ((L2 
    \/ L4) 
    \/ ( 
    LSeg (p10,p2)))); 
    
        
    
        
    
    A168: p00 
    in ( 
    LSeg (p00,p2)) by 
    RLTOPSP1: 68;
    
        p10
    in ( 
    LSeg (p10,p2)) by 
    RLTOPSP1: 68;
    
        then
    
        
    
    A169: p10 
    in (L4 
    /\ ( 
    LSeg (p10,p2))) by 
    Lm25,
    XBOOLE_0:def 4;
    
        p00
    in ( 
    LSeg (p1,p00)) by 
    RLTOPSP1: 68;
    
        then ((
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p00,p2))) 
    <>  
    {} by 
    A168,
    XBOOLE_0:def 4;
    
        then
    
        
    
    A170: (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p00,p2))) 
    =  
    {p00} by
    A167,
    TOPREAL1: 17,
    ZFMISC_1: 33;
    
        p1
    <> p00 or p00 
    <> p2 by 
    A1;
    
        hence P1
    is_an_arc_of (p1,p2) by 
    A170,
    TOPREAL1: 12;
    
        
    
        
    
    A171: L1 
    = (( 
    LSeg (p1,p00)) 
    \/ ( 
    LSeg (p1,p01))) by 
    A3,
    TOPREAL1: 5;
    
        
    
        
    
    A172: L4 
    is_an_arc_of (p11,p10) by 
    Lm9,
    Lm11,
    TOPREAL1: 9;
    
        L2
    is_an_arc_of (p01,p11) by 
    Lm6,
    Lm10,
    TOPREAL1: 9;
    
        then
    
        
    
    A173: (L2 
    \/ L4) 
    is_an_arc_of (p01,p10) by 
    A172,
    TOPREAL1: 2,
    TOPREAL1: 18;
    
        
    
        
    
    A174: ( 
    LSeg (p10,p2)) 
    c= L3 by 
    A165,
    Lm24,
    TOPREAL1: 6;
    
        then
    
        
    
    A175: (L4 
    /\ ( 
    LSeg (p10,p2))) 
    c= (L4 
    /\ L3) by 
    XBOOLE_1: 27;
    
        
    
        
    
    A176: (L2 
    /\ ( 
    LSeg (p10,p2))) 
    =  
    {} by 
    A174,
    Lm2,
    XBOOLE_1: 3,
    XBOOLE_1: 26;
    
        ((L2
    \/ L4) 
    /\ ( 
    LSeg (p10,p2))) 
    = ((L2 
    /\ ( 
    LSeg (p10,p2))) 
    \/ (L4 
    /\ ( 
    LSeg (p10,p2)))) by 
    XBOOLE_1: 23
    
        .=
    {p10} by
    A176,
    A175,
    A169,
    TOPREAL1: 16,
    ZFMISC_1: 33;
    
        then
    
        
    
    A177: ((L2 
    \/ L4) 
    \/ ( 
    LSeg (p10,p2))) 
    is_an_arc_of (p01,p2) by 
    A173,
    TOPREAL1: 10;
    
        
    
        
    
    A178: (( 
    LSeg (p00,p2)) 
    /\ ( 
    LSeg (p10,p2))) 
    =  
    {p2} by
    A165,
    TOPREAL1: 8;
    
        
    
        
    
    A179: L3 
    = (( 
    LSeg (p10,p2)) 
    \/ ( 
    LSeg (p00,p2))) by 
    A165,
    TOPREAL1: 5;
    
        ((
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p10,p2))) 
    c=  
    {p00} by
    A13,
    A174,
    TOPREAL1: 17,
    XBOOLE_1: 27;
    
        then
    
        
    
    A180: (( 
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p10,p2))) 
    =  
    {p00} or ((
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p10,p2))) 
    =  
    {} by 
    ZFMISC_1: 33;
    
        
    
        
    
    A181: ( 
    LSeg (p00,p2)) 
    c= L3 by 
    A165,
    Lm21,
    TOPREAL1: 6;
    
        then
    
        
    
    A182: (( 
    LSeg (p00,p2)) 
    /\ L2) 
    =  
    {} by 
    Lm2,
    XBOOLE_1: 3,
    XBOOLE_1: 27;
    
        
    
        
    
    A183: ex q st q 
    = p2 & (q 
    `1 ) 
    <= 1 & (q 
    `1 ) 
    >=  
    0 & (q 
    `2 ) 
    =  
    0 by 
    A165,
    TOPREAL1: 13;
    
        
    
    A184: 
    
        now
    
          
    
          
    
    A185: (p2 
    `1 ) 
    <= (p10 
    `1 ) by 
    A183,
    EUCLID: 52;
    
          assume
    
          
    
    A186: p00 
    in (( 
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p10,p2))); 
    
          then
    
          
    
    A187: p00 
    in ( 
    LSeg (p1,p01)) by 
    XBOOLE_0:def 4;
    
          p00
    in ( 
    LSeg (p2,p10)) by 
    A186,
    XBOOLE_0:def 4;
    
          then
    
          
    
    A188: (p00 
    `1 ) 
    = (p2 
    `1 ) by 
    A183,
    A185,
    Lm4,
    TOPREAL1: 3;
    
          (p1
    `2 ) 
    <= (p01 
    `2 ) by 
    A15,
    A17,
    EUCLID: 52;
    
          then (p00
    `2 ) 
    = (p1 
    `2 ) by 
    A15,
    A18,
    A187,
    Lm5,
    TOPREAL1: 4;
    
          
    
          then p1
    =  
    |[(p00
    `1 ), (p00 
    `2 )]| by 
    A15,
    A16,
    Lm4,
    EUCLID: 53
    
          .= p2 by
    A183,
    A188,
    Lm5,
    EUCLID: 53;
    
          hence contradiction by
    A1;
    
        end;
    
        ((
    LSeg (p1,p01)) 
    /\ ((L2 
    \/ L4) 
    \/ ( 
    LSeg (p10,p2)))) 
    = ((( 
    LSeg (p1,p01)) 
    /\ (L2 
    \/ L4)) 
    \/ (( 
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p10,p2)))) by 
    XBOOLE_1: 23
    
        .= (((
    LSeg (p1,p01)) 
    /\ L2) 
    \/ (( 
    LSeg (p01,p1)) 
    /\ L4)) by 
    A180,
    A184,
    XBOOLE_1: 23,
    ZFMISC_1: 31
    
        .=
    {p01} by
    A14,
    A10,
    A12,
    XBOOLE_0:def 10;
    
        hence P2
    is_an_arc_of (p1,p2) by 
    A177,
    TOPREAL1: 11;
    
        
    
        thus (P1
    \/ P2) 
    = (( 
    LSeg (p00,p2)) 
    \/ (( 
    LSeg (p1,p00)) 
    \/ (( 
    LSeg (p1,p01)) 
    \/ ((L2 
    \/ L4) 
    \/ ( 
    LSeg (p10,p2)))))) by 
    XBOOLE_1: 4
    
        .= ((L1
    \/ ((L2 
    \/ L4) 
    \/ ( 
    LSeg (p10,p2)))) 
    \/ ( 
    LSeg (p00,p2))) by 
    A171,
    XBOOLE_1: 4
    
        .= (L1
    \/ (((L2 
    \/ L4) 
    \/ ( 
    LSeg (p10,p2))) 
    \/ ( 
    LSeg (p00,p2)))) by 
    XBOOLE_1: 4
    
        .= (L1
    \/ ((L2 
    \/ L4) 
    \/ (( 
    LSeg (p10,p2)) 
    \/ ( 
    LSeg (p00,p2))))) by 
    XBOOLE_1: 4
    
        .= (L1
    \/ (L2 
    \/ (L3 
    \/ L4))) by 
    A179,
    XBOOLE_1: 4
    
        .=
    R^2-unit_square by 
    TOPREAL1:def 2,
    XBOOLE_1: 4;
    
        
    
        
    
    A189: 
    {p1}
    = (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p1,p01))) by 
    A3,
    TOPREAL1: 8;
    
        
    
        
    
    A190: (P1 
    /\ P2) 
    = ((( 
    LSeg (p1,p00)) 
    /\ (( 
    LSeg (p1,p01)) 
    \/ ((L2 
    \/ L4) 
    \/ ( 
    LSeg (p10,p2))))) 
    \/ (( 
    LSeg (p00,p2)) 
    /\ (( 
    LSeg (p1,p01)) 
    \/ ((L2 
    \/ L4) 
    \/ ( 
    LSeg (p10,p2)))))) by 
    XBOOLE_1: 23
    
        .= ((((
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p1,p01))) 
    \/ (( 
    LSeg (p1,p00)) 
    /\ ((L2 
    \/ L4) 
    \/ ( 
    LSeg (p10,p2))))) 
    \/ (( 
    LSeg (p00,p2)) 
    /\ (( 
    LSeg (p1,p01)) 
    \/ ((L2 
    \/ L4) 
    \/ ( 
    LSeg (p10,p2)))))) by 
    XBOOLE_1: 23
    
        .= ((
    {p1}
    \/ ((( 
    LSeg (p1,p00)) 
    /\ (L2 
    \/ L4)) 
    \/ (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p10,p2))))) 
    \/ (( 
    LSeg (p00,p2)) 
    /\ (( 
    LSeg (p1,p01)) 
    \/ ((L2 
    \/ L4) 
    \/ ( 
    LSeg (p10,p2)))))) by 
    A189,
    XBOOLE_1: 23
    
        .= ((
    {p1}
    \/ (((( 
    LSeg (p1,p00)) 
    /\ L2) 
    \/ (( 
    LSeg (p1,p00)) 
    /\ L4)) 
    \/ (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p10,p2))))) 
    \/ (( 
    LSeg (p00,p2)) 
    /\ (( 
    LSeg (p1,p01)) 
    \/ ((L2 
    \/ L4) 
    \/ ( 
    LSeg (p10,p2)))))) by 
    XBOOLE_1: 23
    
        .= ((
    {p1}
    \/ (((( 
    LSeg (p1,p00)) 
    /\ L2) 
    \/ (( 
    LSeg (p1,p00)) 
    /\ L4)) 
    \/ (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p10,p2))))) 
    \/ ((( 
    LSeg (p00,p2)) 
    /\ ( 
    LSeg (p1,p01))) 
    \/ (( 
    LSeg (p00,p2)) 
    /\ ((L2 
    \/ L4) 
    \/ ( 
    LSeg (p10,p2)))))) by 
    XBOOLE_1: 23
    
        .= ((
    {p1}
    \/ (((( 
    LSeg (p1,p00)) 
    /\ L2) 
    \/ (( 
    LSeg (p1,p00)) 
    /\ L4)) 
    \/ (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p10,p2))))) 
    \/ ((( 
    LSeg (p00,p2)) 
    /\ ( 
    LSeg (p1,p01))) 
    \/ ((( 
    LSeg (p00,p2)) 
    /\ (L2 
    \/ L4)) 
    \/  
    {p2}))) by
    A178,
    XBOOLE_1: 23
    
        .= ((
    {p1}
    \/ (((( 
    LSeg (p1,p00)) 
    /\ L2) 
    \/ (( 
    LSeg (p1,p00)) 
    /\ L4)) 
    \/ (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p10,p2))))) 
    \/ ((( 
    LSeg (p00,p2)) 
    /\ ( 
    LSeg (p1,p01))) 
    \/ (((( 
    LSeg (p00,p2)) 
    /\ L2) 
    \/ (( 
    LSeg (p00,p2)) 
    /\ L4)) 
    \/  
    {p2}))) by
    XBOOLE_1: 23
    
        .= ((
    {p1}
    \/ ((( 
    LSeg (p1,p00)) 
    /\ L2) 
    \/ (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p10,p2))))) 
    \/ ((( 
    LSeg (p00,p2)) 
    /\ ( 
    LSeg (p1,p01))) 
    \/ ((( 
    LSeg (p00,p2)) 
    /\ L4) 
    \/  
    {p2}))) by
    A9,
    A182;
    
        
    
    A191: 
    
        now
    
          per cases ;
    
            suppose
    
            
    
    A192: p2 
    = p10; 
    
            then not p2
    in ( 
    LSeg (p1,p00)) by 
    A4,
    Lm4,
    Lm6,
    Lm8,
    TOPREAL1: 3;
    
            then
    
            
    
    A193: ( 
    LSeg (p1,p00)) 
    misses  
    {p2} by
    ZFMISC_1: 50;
    
            ((
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p10,p2))) 
    = (( 
    LSeg (p1,p00)) 
    /\  
    {p2}) by
    A192,
    RLTOPSP1: 70
    
            .=
    {} by 
    A193,
    XBOOLE_0:def 7;
    
            hence (P1
    /\ P2) 
    = (( 
    {p1}
    \/ (( 
    LSeg (p1,p00)) 
    /\ L2)) 
    \/ ((( 
    LSeg (p00,p2)) 
    /\ ( 
    LSeg (p1,p01))) 
    \/  
    {p2})) by
    A190,
    A192,
    TOPREAL1: 16;
    
          end;
    
            suppose
    
            
    
    A194: p2 
    <> p10 & p2 
    <> p00; 
    
            now
    
              assume p00
    in (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p10,p2))); 
    
              then
    
              
    
    A195: p00 
    in ( 
    LSeg (p2,p10)) by 
    XBOOLE_0:def 4;
    
              (p2
    `1 ) 
    <= (p10 
    `1 ) by 
    A183,
    EUCLID: 52;
    
              then (p2
    `1 ) 
    =  
    0 by 
    A183,
    A195,
    Lm4,
    TOPREAL1: 3;
    
              hence contradiction by
    A183,
    A194,
    EUCLID: 53;
    
            end;
    
            then
    
            
    
    A196: 
    {p00}
    <> (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p10,p2))) by 
    ZFMISC_1: 31;
    
            ((
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p10,p2))) 
    c=  
    {p00} by
    A4,
    A174,
    TOPREAL1: 17,
    XBOOLE_1: 27;
    
            then
    
            
    
    A197: (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p10,p2))) 
    =  
    {} by 
    A196,
    ZFMISC_1: 33;
    
            now
    
              assume p10
    in (( 
    LSeg (p00,p2)) 
    /\ L4); 
    
              then
    
              
    
    A198: p10 
    in ( 
    LSeg (p00,p2)) by 
    XBOOLE_0:def 4;
    
              (p00
    `1 ) 
    <= (p2 
    `1 ) by 
    A183,
    EUCLID: 52;
    
              then (p10
    `1 ) 
    <= (p2 
    `1 ) by 
    A198,
    TOPREAL1: 3;
    
              then (p2
    `1 ) 
    = (p10 
    `1 ) by 
    A183,
    Lm8,
    XXREAL_0: 1;
    
              hence contradiction by
    A183,
    A194,
    Lm8,
    EUCLID: 53;
    
            end;
    
            then
    
            
    
    A199: 
    {p10}
    <> (( 
    LSeg (p00,p2)) 
    /\ L4) by 
    ZFMISC_1: 31;
    
            ((
    LSeg (p00,p2)) 
    /\ L4) 
    c=  
    {p10} by
    A181,
    TOPREAL1: 16,
    XBOOLE_1: 27;
    
            then ((
    LSeg (p00,p2)) 
    /\ L4) 
    =  
    {} by 
    A199,
    ZFMISC_1: 33;
    
            hence (P1
    /\ P2) 
    = (( 
    {p1}
    \/ (( 
    LSeg (p1,p00)) 
    /\ L2)) 
    \/ ((( 
    LSeg (p00,p2)) 
    /\ ( 
    LSeg (p1,p01))) 
    \/  
    {p2})) by
    A190,
    A197;
    
          end;
    
            suppose
    
            
    
    A200: p2 
    = p00; 
    
            then p2
    in ( 
    LSeg (p1,p00)) by 
    RLTOPSP1: 68;
    
            then
    
            
    
    A201: (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p10,p2))) 
    <>  
    {} by 
    A200,
    Lm21,
    XBOOLE_0:def 4;
    
            ((
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p10,p2))) 
    c=  
    {p2} by
    A4,
    A200,
    TOPREAL1: 17,
    XBOOLE_1: 27;
    
            then
    
            
    
    A202: (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p10,p2))) 
    =  
    {p2} by
    A201,
    ZFMISC_1: 33;
    
            ((
    LSeg (p00,p2)) 
    /\ L4) 
    = ( 
    {p00}
    /\ L4) by 
    A200,
    RLTOPSP1: 70
    
            .=
    {} by 
    Lm1,
    Lm12;
    
            
    
            hence (P1
    /\ P2) 
    = ((( 
    {p1}
    \/ (( 
    LSeg (p1,p00)) 
    /\ L2)) 
    \/  
    {p2})
    \/ ((( 
    LSeg (p00,p2)) 
    /\ ( 
    LSeg (p1,p01))) 
    \/  
    {p2})) by
    A190,
    A202,
    XBOOLE_1: 4
    
            .= ((
    {p1}
    \/ (( 
    LSeg (p1,p00)) 
    /\ L2)) 
    \/ (((( 
    LSeg (p00,p2)) 
    /\ ( 
    LSeg (p1,p01))) 
    \/  
    {p2})
    \/  
    {p2})) by
    XBOOLE_1: 4
    
            .= ((
    {p1}
    \/ (( 
    LSeg (p1,p00)) 
    /\ L2)) 
    \/ ((( 
    LSeg (p00,p2)) 
    /\ ( 
    LSeg (p1,p01))) 
    \/ ( 
    {p2}
    \/  
    {p2}))) by
    XBOOLE_1: 4
    
            .= ((
    {p1}
    \/ (( 
    LSeg (p1,p00)) 
    /\ L2)) 
    \/ ((( 
    LSeg (p00,p2)) 
    /\ ( 
    LSeg (p1,p01))) 
    \/  
    {p2}));
    
          end;
    
        end;
    
        now
    
          per cases ;
    
            suppose
    
            
    
    A203: p1 
    = p01; 
    
            then
    
            
    
    A204: (( 
    LSeg (p00,p2)) 
    /\ ( 
    LSeg (p1,p01))) 
    = (( 
    LSeg (p00,p2)) 
    /\  
    {p1}) by
    RLTOPSP1: 70;
    
             not p1
    in ( 
    LSeg (p00,p2)) by 
    A181,
    A203,
    Lm5,
    Lm7,
    Lm9,
    TOPREAL1: 4;
    
            then ((
    LSeg (p00,p2)) 
    /\ ( 
    LSeg (p1,p01))) 
    =  
    {} by 
    A204,
    Lm1;
    
            hence thesis by
    A191,
    A203,
    ENUMSET1: 1,
    TOPREAL1: 15;
    
          end;
    
            suppose
    
            
    
    A205: p1 
    = p00; 
    
            p00
    in ( 
    LSeg (p00,p2)) by 
    RLTOPSP1: 68;
    
            then
    
            
    
    A206: (( 
    LSeg (p00,p2)) 
    /\ ( 
    LSeg (p1,p01))) 
    <>  
    {} by 
    A205,
    Lm20,
    XBOOLE_0:def 4;
    
            ((
    LSeg (p1,p00)) 
    /\ L2) 
    = ( 
    {p1}
    /\ L2) by 
    A205,
    RLTOPSP1: 70;
    
            then
    
            
    
    A207: (( 
    LSeg (p1,p00)) 
    /\ L2) 
    =  
    {} by 
    A205,
    Lm1,
    Lm13;
    
            ((
    LSeg (p00,p2)) 
    /\ ( 
    LSeg (p1,p01))) 
    c= (L3 
    /\ L1) by 
    A165,
    A205,
    Lm21,
    TOPREAL1: 6,
    XBOOLE_1: 26;
    
            then ((
    LSeg (p00,p2)) 
    /\ ( 
    LSeg (p1,p01))) 
    =  
    {p1} by
    A205,
    A206,
    TOPREAL1: 17,
    ZFMISC_1: 33;
    
            
    
            hence (P1
    /\ P2) 
    = (( 
    {p1}
    \/  
    {p1})
    \/  
    {p2}) by
    A191,
    A207,
    XBOOLE_1: 4
    
            .=
    {p1, p2} by
    ENUMSET1: 1;
    
          end;
    
            suppose
    
            
    
    A208: p1 
    <> p00 & p1 
    <> p01; 
    
            now
    
              assume p00
    in (( 
    LSeg (p00,p2)) 
    /\ ( 
    LSeg (p1,p01))); 
    
              then
    
              
    
    A209: p00 
    in ( 
    LSeg (p1,p01)) by 
    XBOOLE_0:def 4;
    
              (p1
    `2 ) 
    <= (p01 
    `2 ) by 
    A15,
    A17,
    EUCLID: 52;
    
              then (p1
    `2 ) 
    =  
    0 by 
    A15,
    A18,
    A209,
    Lm5,
    TOPREAL1: 4;
    
              hence contradiction by
    A15,
    A16,
    A208,
    EUCLID: 53;
    
            end;
    
            then
    
            
    
    A210: 
    {p00}
    <> (( 
    LSeg (p00,p2)) 
    /\ ( 
    LSeg (p1,p01))) by 
    ZFMISC_1: 31;
    
            ((
    LSeg (p00,p2)) 
    /\ ( 
    LSeg (p1,p01))) 
    c= (L3 
    /\ L1) by 
    A13,
    A181,
    XBOOLE_1: 27;
    
            then
    
            
    
    A211: (( 
    LSeg (p00,p2)) 
    /\ ( 
    LSeg (p1,p01))) 
    =  
    {} by 
    A210,
    TOPREAL1: 17,
    ZFMISC_1: 33;
    
            now
    
              assume p01
    in (( 
    LSeg (p1,p00)) 
    /\ L2); 
    
              then
    
              
    
    A212: p01 
    in ( 
    LSeg (p00,p1)) by 
    XBOOLE_0:def 4;
    
              (p00
    `2 ) 
    <= (p1 
    `2 ) by 
    A15,
    A18,
    EUCLID: 52;
    
              then (p01
    `2 ) 
    <= (p1 
    `2 ) by 
    A212,
    TOPREAL1: 4;
    
              then (p1
    `2 ) 
    = 1 by 
    A15,
    A17,
    Lm7,
    XXREAL_0: 1;
    
              hence contradiction by
    A15,
    A16,
    A208,
    EUCLID: 53;
    
            end;
    
            then
    
            
    
    A213: 
    {p01}
    <> (( 
    LSeg (p1,p00)) 
    /\ L2) by 
    ZFMISC_1: 31;
    
            ((
    LSeg (p1,p00)) 
    /\ L2) 
    c=  
    {p01} by
    A4,
    TOPREAL1: 15,
    XBOOLE_1: 27;
    
            then ((
    LSeg (p1,p00)) 
    /\ L2) 
    =  
    {} by 
    A213,
    ZFMISC_1: 33;
    
            hence thesis by
    A191,
    A211,
    ENUMSET1: 1;
    
          end;
    
        end;
    
        hence thesis;
    
      end;
    
        suppose
    
        
    
    A214: p2 
    in L4; 
    
        now
    
          let a be
    object;
    
          assume
    
          
    
    A215: a 
    in (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p1,p01))); 
    
          then
    
          reconsider p = a as
    Point of ( 
    TOP-REAL 2); 
    
          a
    in ( 
    LSeg (p1,p01)) by 
    A215,
    XBOOLE_0:def 4;
    
          then
    
          
    
    A216: (p1 
    `2 ) 
    <= (p 
    `2 ) by 
    A15,
    A17,
    Lm7,
    TOPREAL1: 4;
    
          
    
          
    
    A217: a 
    in ( 
    LSeg (p00,p1)) by 
    A215,
    XBOOLE_0:def 4;
    
          then (p
    `2 ) 
    <= (p1 
    `2 ) by 
    A15,
    A18,
    Lm5,
    TOPREAL1: 4;
    
          then
    
          
    
    A218: (p 
    `2 ) 
    = (p1 
    `2 ) by 
    A216,
    XXREAL_0: 1;
    
          (p
    `1 ) 
    <= (p1 
    `1 ) by 
    A15,
    A16,
    A217,
    Lm4,
    TOPREAL1: 3;
    
          then (p
    `1 ) 
    = (p1 
    `1 ) by 
    A15,
    A16,
    A217,
    Lm4,
    TOPREAL1: 3;
    
          
    
          then a
    =  
    |[(p1
    `1 ), (p1 
    `2 )]| by 
    A218,
    EUCLID: 53
    
          .= p1 by
    EUCLID: 53;
    
          hence a
    in  
    {p1} by
    TARSKI:def 1;
    
        end;
    
        then
    
        
    
    A219: (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p1,p01))) 
    c=  
    {p1};
    
        
    
        
    
    A220: p2 
    in ( 
    LSeg (p11,p2)) by 
    RLTOPSP1: 68;
    
        p2
    in ( 
    LSeg (p10,p2)) by 
    RLTOPSP1: 68;
    
        then p2
    in (( 
    LSeg (p10,p2)) 
    /\ ( 
    LSeg (p11,p2))) by 
    A220,
    XBOOLE_0:def 4;
    
        then
    
        
    
    A221: 
    {p2}
    c= (( 
    LSeg (p10,p2)) 
    /\ ( 
    LSeg (p11,p2))) by 
    ZFMISC_1: 31;
    
        
    
        
    
    A222: ex q st q 
    = p2 & (q 
    `1 ) 
    = 1 & (q 
    `2 ) 
    <= 1 & (q 
    `2 ) 
    >=  
    0 by 
    A214,
    TOPREAL1: 13;
    
        now
    
          let a be
    object;
    
          assume
    
          
    
    A223: a 
    in (( 
    LSeg (p10,p2)) 
    /\ ( 
    LSeg (p11,p2))); 
    
          then
    
          reconsider p = a as
    Point of ( 
    TOP-REAL 2); 
    
          
    
          
    
    A224: a 
    in ( 
    LSeg (p10,p2)) by 
    A223,
    XBOOLE_0:def 4;
    
          then
    
          
    
    A225: (p2 
    `1 ) 
    <= (p 
    `1 ) by 
    A222,
    Lm8,
    TOPREAL1: 3;
    
          a
    in ( 
    LSeg (p2,p11)) by 
    A223,
    XBOOLE_0:def 4;
    
          then
    
          
    
    A226: (p2 
    `2 ) 
    <= (p 
    `2 ) by 
    A222,
    Lm11,
    TOPREAL1: 4;
    
          (p
    `1 ) 
    <= (p2 
    `1 ) by 
    A222,
    A224,
    Lm8,
    TOPREAL1: 3;
    
          then
    
          
    
    A227: (p 
    `1 ) 
    = (p2 
    `1 ) by 
    A225,
    XXREAL_0: 1;
    
          (p
    `2 ) 
    <= (p2 
    `2 ) by 
    A222,
    A224,
    Lm9,
    TOPREAL1: 4;
    
          then (p
    `2 ) 
    = (p2 
    `2 ) by 
    A226,
    XXREAL_0: 1;
    
          
    
          then a
    =  
    |[(p2
    `1 ), (p2 
    `2 )]| by 
    A227,
    EUCLID: 53
    
          .= p2 by
    EUCLID: 53;
    
          hence a
    in  
    {p2} by
    TARSKI:def 1;
    
        end;
    
        then
    
        
    
    A228: (( 
    LSeg (p10,p2)) 
    /\ ( 
    LSeg (p11,p2))) 
    c=  
    {p2};
    
        (
    LSeg (p10,p2)) 
    c= L4 by 
    A214,
    Lm25,
    TOPREAL1: 6;
    
        then
    
        
    
    A229: (L3 
    /\ ( 
    LSeg (p10,p2))) 
    c=  
    {p10} by
    TOPREAL1: 16,
    XBOOLE_1: 27;
    
        take P1 = (((
    LSeg (p1,p00)) 
    \/ L3) 
    \/ ( 
    LSeg (p10,p2))), P2 = ((( 
    LSeg (p1,p01)) 
    \/ L2) 
    \/ ( 
    LSeg (p11,p2))); 
    
        
    
        
    
    A230: p10 
    in ( 
    LSeg (p10,p2)) by 
    RLTOPSP1: 68;
    
        p10
    in L3 by 
    RLTOPSP1: 68;
    
        then (L3
    /\ ( 
    LSeg (p10,p2))) 
    <>  
    {} by 
    A230,
    XBOOLE_0:def 4;
    
        then (L3
    /\ ( 
    LSeg (p10,p2))) 
    =  
    {p10} by
    A229,
    ZFMISC_1: 33;
    
        then
    
        
    
    A231: (L3 
    \/ ( 
    LSeg (p10,p2))) 
    is_an_arc_of (p00,p2) by 
    Lm4,
    Lm8,
    TOPREAL1: 12;
    
        (
    LSeg (p10,p2)) 
    c= L4 by 
    A214,
    Lm25,
    TOPREAL1: 6;
    
        then
    
        
    
    A232: (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p10,p2))) 
    =  
    {} by 
    A4,
    Lm3,
    XBOOLE_1: 3,
    XBOOLE_1: 27;
    
        ((
    LSeg (p1,p00)) 
    /\ (L3 
    \/ ( 
    LSeg (p10,p2)))) 
    = ((( 
    LSeg (p1,p00)) 
    /\ L3) 
    \/ (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p10,p2)))) by 
    XBOOLE_1: 23
    
        .=
    {p00} by
    A5,
    A6,
    A232,
    TOPREAL1: 17,
    XBOOLE_0:def 10;
    
        then ((
    LSeg (p1,p00)) 
    \/ (L3 
    \/ ( 
    LSeg (p10,p2)))) 
    is_an_arc_of (p1,p2) by 
    A231,
    TOPREAL1: 11;
    
        hence P1
    is_an_arc_of (p1,p2) by 
    XBOOLE_1: 4;
    
        p11
    in ( 
    LSeg (p11,p2)) by 
    RLTOPSP1: 68;
    
        then
    
        
    
    A233: (L2 
    /\ ( 
    LSeg (p11,p2))) 
    <>  
    {} by 
    Lm26,
    XBOOLE_0:def 4;
    
        
    
        
    
    A234: ( 
    LSeg (p11,p2)) 
    c= L4 by 
    A214,
    Lm27,
    TOPREAL1: 6;
    
        then
    
        
    
    A235: (( 
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p11,p2))) 
    =  
    {} by 
    A13,
    Lm3,
    XBOOLE_1: 3,
    XBOOLE_1: 27;
    
        (L2
    /\ ( 
    LSeg (p11,p2))) 
    c=  
    {p11} by
    A234,
    TOPREAL1: 18,
    XBOOLE_1: 27;
    
        then (L2
    /\ ( 
    LSeg (p11,p2))) 
    =  
    {p11} by
    A233,
    ZFMISC_1: 33;
    
        then
    
        
    
    A236: (L2 
    \/ ( 
    LSeg (p11,p2))) 
    is_an_arc_of (p01,p2) by 
    Lm6,
    Lm10,
    TOPREAL1: 12;
    
        ((
    LSeg (p1,p01)) 
    /\ (L2 
    \/ ( 
    LSeg (p11,p2)))) 
    = ((( 
    LSeg (p1,p01)) 
    /\ L2) 
    \/ (( 
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p11,p2)))) by 
    XBOOLE_1: 23
    
        .=
    {p01} by
    A10,
    A12,
    A235,
    XBOOLE_0:def 10;
    
        then ((
    LSeg (p1,p01)) 
    \/ (L2 
    \/ ( 
    LSeg (p11,p2)))) 
    is_an_arc_of (p1,p2) by 
    A236,
    TOPREAL1: 11;
    
        hence P2
    is_an_arc_of (p1,p2) by 
    XBOOLE_1: 4;
    
        
    
        thus
    R^2-unit_square  
    = (((( 
    LSeg (p1,p00)) 
    \/ ( 
    LSeg (p1,p01))) 
    \/ L2) 
    \/ (L3 
    \/ L4)) by 
    A3,
    TOPREAL1: 5,
    TOPREAL1:def 2
    
        .= (((
    LSeg (p1,p00)) 
    \/ (( 
    LSeg (p1,p01)) 
    \/ L2)) 
    \/ (L3 
    \/ L4)) by 
    XBOOLE_1: 4
    
        .= ((
    LSeg (p1,p00)) 
    \/ ((( 
    LSeg (p1,p01)) 
    \/ L2) 
    \/ (L3 
    \/ L4))) by 
    XBOOLE_1: 4
    
        .= ((
    LSeg (p1,p00)) 
    \/ (L3 
    \/ ((( 
    LSeg (p1,p01)) 
    \/ L2) 
    \/ L4))) by 
    XBOOLE_1: 4
    
        .= (((
    LSeg (p1,p00)) 
    \/ L3) 
    \/ ((( 
    LSeg (p1,p01)) 
    \/ L2) 
    \/ L4)) by 
    XBOOLE_1: 4
    
        .= (((
    LSeg (p1,p00)) 
    \/ L3) 
    \/ ((( 
    LSeg (p1,p01)) 
    \/ L2) 
    \/ (( 
    LSeg (p11,p2)) 
    \/ ( 
    LSeg (p10,p2))))) by 
    A214,
    TOPREAL1: 5
    
        .= (((
    LSeg (p1,p00)) 
    \/ L3) 
    \/ (( 
    LSeg (p10,p2)) 
    \/ ((( 
    LSeg (p1,p01)) 
    \/ L2) 
    \/ ( 
    LSeg (p11,p2))))) by 
    XBOOLE_1: 4
    
        .= (P1
    \/ P2) by 
    XBOOLE_1: 4;
    
        
    
        
    
    A237: p1 
    in ( 
    LSeg (p1,p01)) by 
    RLTOPSP1: 68;
    
        p1
    in ( 
    LSeg (p1,p00)) by 
    RLTOPSP1: 68;
    
        then p1
    in (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p1,p01))) by 
    A237,
    XBOOLE_0:def 4;
    
        then
    {p1}
    c= (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p1,p01))) by 
    ZFMISC_1: 31;
    
        then
    
        
    
    A238: (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p1,p01))) 
    =  
    {p1} by
    A219,
    XBOOLE_0:def 10;
    
        
    
        
    
    A239: (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p11,p2))) 
    =  
    {} by 
    A4,
    A234,
    Lm3,
    XBOOLE_1: 3,
    XBOOLE_1: 27;
    
        
    
        
    
    A240: ( 
    LSeg (p10,p2)) 
    c= L4 by 
    A214,
    Lm25,
    TOPREAL1: 6;
    
        then
    
        
    
    A241: (( 
    LSeg (p10,p2)) 
    /\ ( 
    LSeg (p1,p01))) 
    =  
    {} by 
    A13,
    Lm3,
    XBOOLE_1: 3,
    XBOOLE_1: 27;
    
        
    
        
    
    A242: (P1 
    /\ P2) 
    = (((( 
    LSeg (p1,p00)) 
    \/ L3) 
    /\ ((( 
    LSeg (p1,p01)) 
    \/ L2) 
    \/ ( 
    LSeg (p11,p2)))) 
    \/ (( 
    LSeg (p10,p2)) 
    /\ ((( 
    LSeg (p1,p01)) 
    \/ L2) 
    \/ ( 
    LSeg (p11,p2))))) by 
    XBOOLE_1: 23
    
        .= ((((
    LSeg (p1,p00)) 
    /\ ((( 
    LSeg (p1,p01)) 
    \/ L2) 
    \/ ( 
    LSeg (p11,p2)))) 
    \/ (L3 
    /\ ((( 
    LSeg (p1,p01)) 
    \/ L2) 
    \/ ( 
    LSeg (p11,p2))))) 
    \/ (( 
    LSeg (p10,p2)) 
    /\ ((( 
    LSeg (p1,p01)) 
    \/ L2) 
    \/ ( 
    LSeg (p11,p2))))) by 
    XBOOLE_1: 23
    
        .= (((((
    LSeg (p1,p00)) 
    /\ (( 
    LSeg (p1,p01)) 
    \/ L2)) 
    \/ (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p11,p2)))) 
    \/ (L3 
    /\ ((( 
    LSeg (p1,p01)) 
    \/ L2) 
    \/ ( 
    LSeg (p11,p2))))) 
    \/ (( 
    LSeg (p10,p2)) 
    /\ ((( 
    LSeg (p1,p01)) 
    \/ L2) 
    \/ ( 
    LSeg (p11,p2))))) by 
    XBOOLE_1: 23
    
        .= (((((
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p1,p01))) 
    \/ (( 
    LSeg (p1,p00)) 
    /\ L2)) 
    \/ (L3 
    /\ ((( 
    LSeg (p1,p01)) 
    \/ L2) 
    \/ ( 
    LSeg (p11,p2))))) 
    \/ (( 
    LSeg (p10,p2)) 
    /\ ((( 
    LSeg (p1,p01)) 
    \/ L2) 
    \/ ( 
    LSeg (p11,p2))))) by 
    A239,
    XBOOLE_1: 23
    
        .= (((
    {p1}
    \/ (( 
    LSeg (p1,p00)) 
    /\ L2)) 
    \/ ((L3 
    /\ (( 
    LSeg (p1,p01)) 
    \/ L2)) 
    \/ (L3 
    /\ ( 
    LSeg (p11,p2))))) 
    \/ (( 
    LSeg (p10,p2)) 
    /\ ((( 
    LSeg (p1,p01)) 
    \/ L2) 
    \/ ( 
    LSeg (p11,p2))))) by 
    A238,
    XBOOLE_1: 23
    
        .= (((
    {p1}
    \/ (( 
    LSeg (p1,p00)) 
    /\ L2)) 
    \/ (((L3 
    /\ ( 
    LSeg (p1,p01))) 
    \/ (L3 
    /\ L2)) 
    \/ (L3 
    /\ ( 
    LSeg (p11,p2))))) 
    \/ (( 
    LSeg (p10,p2)) 
    /\ ((( 
    LSeg (p1,p01)) 
    \/ L2) 
    \/ ( 
    LSeg (p11,p2))))) by 
    XBOOLE_1: 23
    
        .= (((
    {p1}
    \/ (( 
    LSeg (p1,p00)) 
    /\ L2)) 
    \/ ((L3 
    /\ ( 
    LSeg (p1,p01))) 
    \/ (L3 
    /\ ( 
    LSeg (p11,p2))))) 
    \/ ((( 
    LSeg (p10,p2)) 
    /\ (( 
    LSeg (p1,p01)) 
    \/ L2)) 
    \/ (( 
    LSeg (p10,p2)) 
    /\ ( 
    LSeg (p11,p2))))) by 
    Lm2,
    XBOOLE_1: 23
    
        .= (((
    {p1}
    \/ (( 
    LSeg (p1,p00)) 
    /\ L2)) 
    \/ ((L3 
    /\ ( 
    LSeg (p1,p01))) 
    \/ (L3 
    /\ ( 
    LSeg (p11,p2))))) 
    \/ ((( 
    LSeg (p10,p2)) 
    /\ (( 
    LSeg (p1,p01)) 
    \/ L2)) 
    \/  
    {p2})) by
    A221,
    A228,
    XBOOLE_0:def 10
    
        .= (((
    {p1}
    \/ (( 
    LSeg (p1,p00)) 
    /\ L2)) 
    \/ ((L3 
    /\ ( 
    LSeg (p1,p01))) 
    \/ (L3 
    /\ ( 
    LSeg (p11,p2))))) 
    \/ (((( 
    LSeg (p10,p2)) 
    /\ ( 
    LSeg (p1,p01))) 
    \/ (( 
    LSeg (p10,p2)) 
    /\ L2)) 
    \/  
    {p2})) by
    XBOOLE_1: 23
    
        .= (((
    {p1}
    \/ (( 
    LSeg (p1,p00)) 
    /\ L2)) 
    \/ ((L3 
    /\ ( 
    LSeg (p1,p01))) 
    \/ (L3 
    /\ ( 
    LSeg (p11,p2))))) 
    \/ ((( 
    LSeg (p10,p2)) 
    /\ L2) 
    \/  
    {p2})) by
    A241;
    
        
    
    A243: 
    
        now
    
          per cases ;
    
            suppose
    
            
    
    A244: p2 
    = p11; 
    
            
    
            then (L3
    /\ ( 
    LSeg (p11,p2))) 
    = (L3 
    /\  
    {p11}) by
    RLTOPSP1: 70
    
            .=
    {} by 
    Lm1,
    Lm19;
    
            hence (P1
    /\ P2) 
    = ((( 
    {p1}
    \/ (( 
    LSeg (p1,p00)) 
    /\ L2)) 
    \/ (L3 
    /\ ( 
    LSeg (p1,p01)))) 
    \/  
    {p2}) by
    A242,
    A244,
    TOPREAL1: 18;
    
          end;
    
            suppose
    
            
    
    A245: p2 
    = p10; 
    
            
    
            then ((
    LSeg (p10,p2)) 
    /\ L2) 
    = ( 
    {p10}
    /\ L2) by 
    RLTOPSP1: 70
    
            .=
    {} by 
    Lm1,
    Lm17;
    
            
    
            hence (P1
    /\ P2) 
    = (( 
    {p1}
    \/ (( 
    LSeg (p1,p00)) 
    /\ L2)) 
    \/ (((L3 
    /\ ( 
    LSeg (p1,p01))) 
    \/  
    {p2})
    \/  
    {p2})) by
    A242,
    A245,
    TOPREAL1: 16,
    XBOOLE_1: 4
    
            .= ((
    {p1}
    \/ (( 
    LSeg (p1,p00)) 
    /\ L2)) 
    \/ ((L3 
    /\ ( 
    LSeg (p1,p01))) 
    \/ ( 
    {p2}
    \/  
    {p2}))) by
    XBOOLE_1: 4
    
            .= (((
    {p1}
    \/ (( 
    LSeg (p1,p00)) 
    /\ L2)) 
    \/ (L3 
    /\ ( 
    LSeg (p1,p01)))) 
    \/  
    {p2}) by
    XBOOLE_1: 4;
    
          end;
    
            suppose
    
            
    
    A246: p2 
    <> p10 & p2 
    <> p11; 
    
            now
    
              assume p11
    in (( 
    LSeg (p10,p2)) 
    /\ L2); 
    
              then
    
              
    
    A247: p11 
    in ( 
    LSeg (p10,p2)) by 
    XBOOLE_0:def 4;
    
              (p10
    `2 ) 
    <= (p2 
    `2 ) by 
    A222,
    EUCLID: 52;
    
              then (p11
    `2 ) 
    <= (p2 
    `2 ) by 
    A247,
    TOPREAL1: 4;
    
              then (p11
    `2 ) 
    = (p2 
    `2 ) by 
    A222,
    Lm11,
    XXREAL_0: 1;
    
              
    
              then p2
    =  
    |[(p11
    `1 ), (p11 
    `2 )]| by 
    A222,
    Lm10,
    EUCLID: 53
    
              .= p11 by
    EUCLID: 53;
    
              hence contradiction by
    A246;
    
            end;
    
            then
    
            
    
    A248: 
    {p11}
    <> (( 
    LSeg (p10,p2)) 
    /\ L2) by 
    ZFMISC_1: 31;
    
            ((
    LSeg (p10,p2)) 
    /\ L2) 
    c= (L4 
    /\ L2) by 
    A240,
    XBOOLE_1: 27;
    
            then
    
            
    
    A249: (( 
    LSeg (p10,p2)) 
    /\ L2) 
    =  
    {} by 
    A248,
    TOPREAL1: 18,
    ZFMISC_1: 33;
    
            now
    
              assume p10
    in (L3 
    /\ ( 
    LSeg (p11,p2))); 
    
              then
    
              
    
    A250: p10 
    in ( 
    LSeg (p2,p11)) by 
    XBOOLE_0:def 4;
    
              (p2
    `2 ) 
    <= (p11 
    `2 ) by 
    A222,
    EUCLID: 52;
    
              then (p2
    `2 ) 
    = (p10 
    `2 ) by 
    A222,
    A250,
    Lm9,
    TOPREAL1: 4;
    
              
    
              then p2
    =  
    |[(p10
    `1 ), (p10 
    `2 )]| by 
    A222,
    Lm8,
    EUCLID: 53
    
              .= p10 by
    EUCLID: 53;
    
              hence contradiction by
    A246;
    
            end;
    
            then
    
            
    
    A251: (L3 
    /\ ( 
    LSeg (p11,p2))) 
    <>  
    {p10} by
    ZFMISC_1: 31;
    
            (L3
    /\ ( 
    LSeg (p11,p2))) 
    c=  
    {p10} by
    A234,
    TOPREAL1: 16,
    XBOOLE_1: 27;
    
            then (L3
    /\ ( 
    LSeg (p11,p2))) 
    =  
    {} by 
    A251,
    ZFMISC_1: 33;
    
            hence (P1
    /\ P2) 
    = ((( 
    {p1}
    \/ (( 
    LSeg (p1,p00)) 
    /\ L2)) 
    \/ (L3 
    /\ ( 
    LSeg (p1,p01)))) 
    \/  
    {p2}) by
    A242,
    A249;
    
          end;
    
        end;
    
        now
    
          per cases ;
    
            suppose
    
            
    
    A252: p1 
    = p01; 
    
            
    
            then (L3
    /\ ( 
    LSeg (p1,p01))) 
    = (L3 
    /\  
    {p01}) by
    RLTOPSP1: 70
    
            .=
    {} by 
    Lm1,
    Lm14;
    
            hence thesis by
    A243,
    A252,
    ENUMSET1: 1,
    TOPREAL1: 15;
    
          end;
    
            suppose
    
            
    
    A253: p1 
    <> p01 & p1 
    <> p00; 
    
            now
    
              assume p01
    in (( 
    LSeg (p1,p00)) 
    /\ L2); 
    
              then
    
              
    
    A254: p01 
    in ( 
    LSeg (p00,p1)) by 
    XBOOLE_0:def 4;
    
              (p00
    `2 ) 
    <= (p1 
    `2 ) by 
    A15,
    A18,
    EUCLID: 52;
    
              then (p01
    `2 ) 
    <= (p1 
    `2 ) by 
    A254,
    TOPREAL1: 4;
    
              then (p1
    `2 ) 
    = (p01 
    `2 ) by 
    A15,
    A17,
    Lm7,
    XXREAL_0: 1;
    
              
    
              then p1
    =  
    |[(p01
    `1 ), (p01 
    `2 )]| by 
    A15,
    A16,
    Lm6,
    EUCLID: 53
    
              .= p01 by
    EUCLID: 53;
    
              hence contradiction by
    A253;
    
            end;
    
            then
    
            
    
    A255: 
    {p01}
    <> (( 
    LSeg (p1,p00)) 
    /\ L2) by 
    ZFMISC_1: 31;
    
            ((
    LSeg (p1,p00)) 
    /\ L2) 
    c=  
    {p01} by
    A4,
    TOPREAL1: 15,
    XBOOLE_1: 27;
    
            then
    
            
    
    A256: (( 
    LSeg (p1,p00)) 
    /\ L2) 
    =  
    {} by 
    A255,
    ZFMISC_1: 33;
    
            now
    
              assume p00
    in (L3 
    /\ ( 
    LSeg (p1,p01))); 
    
              then p00
    in ( 
    LSeg (p1,p01)) by 
    XBOOLE_0:def 4;
    
              then (p1
    `2 ) 
    = (p00 
    `2 ) by 
    A15,
    A17,
    A18,
    Lm5,
    Lm7,
    TOPREAL1: 4;
    
              
    
              then p1
    =  
    |[(p00
    `1 ), (p00 
    `2 )]| by 
    A15,
    A16,
    Lm4,
    EUCLID: 53
    
              .= p00 by
    EUCLID: 53;
    
              hence contradiction by
    A253;
    
            end;
    
            then
    
            
    
    A257: 
    {p00}
    <> (L3 
    /\ ( 
    LSeg (p1,p01))) by 
    ZFMISC_1: 31;
    
            (L3
    /\ ( 
    LSeg (p1,p01))) 
    c= (L3 
    /\ L1) by 
    A13,
    XBOOLE_1: 27;
    
            then (L3
    /\ ( 
    LSeg (p1,p01))) 
    =  
    {} by 
    A257,
    TOPREAL1: 17,
    ZFMISC_1: 33;
    
            hence thesis by
    A243,
    A256,
    ENUMSET1: 1;
    
          end;
    
            suppose
    
            
    
    A258: p1 
    = p00; 
    
            
    
            then ((
    LSeg (p1,p00)) 
    /\ L2) 
    = ( 
    {p00}
    /\ L2) by 
    RLTOPSP1: 70
    
            .=
    {} by 
    Lm1,
    Lm13;
    
            hence thesis by
    A243,
    A258,
    ENUMSET1: 1,
    TOPREAL1: 17;
    
          end;
    
        end;
    
        hence thesis;
    
      end;
    
    end;
    
    
    
    
    
    Lm31: p1 
    <> p2 & p2 
    in  
    R^2-unit_square & p1 
    in ( 
    LSeg (p01,p11)) implies ex P1,P2 be non 
    empty  
    Subset of ( 
    TOP-REAL 2) st P1 
    is_an_arc_of (p1,p2) & P2 
    is_an_arc_of (p1,p2) & 
    R^2-unit_square  
    = (P1 
    \/ P2) & (P1 
    /\ P2) 
    =  
    {p1, p2}
    
    proof
    
      assume that
    
      
    
    A1: p1 
    <> p2 and 
    
      
    
    A2: p2 
    in  
    R^2-unit_square and 
    
      
    
    A3: p1 
    in ( 
    LSeg (p01,p11)); 
    
      
    
      
    
    A4: p2 
    in (L1 
    \/ L2) or p2 
    in (L3 
    \/ L4) by 
    A2,
    TOPREAL1:def 2,
    XBOOLE_0:def 3;
    
      
    
      
    
    A5: (( 
    LSeg (p01,p1)) 
    /\ L1) 
    c= (L2 
    /\ L1) by 
    A3,
    Lm23,
    TOPREAL1: 6,
    XBOOLE_1: 26;
    
      p11
    in ( 
    LSeg (p1,p11)) by 
    RLTOPSP1: 68;
    
      then
    
      
    
    A6: (( 
    LSeg (p1,p11)) 
    /\ L4) 
    <>  
    {} by 
    Lm27,
    XBOOLE_0:def 4;
    
      p01
    in ( 
    LSeg (p01,p1)) by 
    RLTOPSP1: 68;
    
      then
    
      
    
    A7: (( 
    LSeg (p01,p1)) 
    /\ L1) 
    <>  
    {} by 
    Lm22,
    XBOOLE_0:def 4;
    
      
    
      
    
    A8: ( 
    LSeg (p1,p11)) 
    c= L2 by 
    A3,
    Lm26,
    TOPREAL1: 6;
    
      then
    
      
    
    A9: (( 
    LSeg (p1,p11)) 
    /\ L3) 
    =  
    {} by 
    Lm2,
    XBOOLE_1: 3,
    XBOOLE_1: 26;
    
      
    
      
    
    A10: (( 
    LSeg (p1,p11)) 
    /\ L4) 
    c=  
    {p11} by
    A3,
    Lm26,
    TOPREAL1: 6,
    TOPREAL1: 18,
    XBOOLE_1: 26;
    
      
    
      
    
    A11: ( 
    LSeg (p01,p1)) 
    c= L2 by 
    A3,
    Lm23,
    TOPREAL1: 6;
    
      then
    
      
    
    A12: (( 
    LSeg (p1,p01)) 
    /\ L3) 
    =  
    {} by 
    Lm2,
    XBOOLE_1: 3,
    XBOOLE_1: 26;
    
      consider q1 such that
    
      
    
    A13: q1 
    = p1 and 
    
      
    
    A14: (q1 
    `1 ) 
    <= 1 and 
    
      
    
    A15: (q1 
    `1 ) 
    >=  
    0 and 
    
      
    
    A16: (q1 
    `2 ) 
    = 1 by 
    A3,
    TOPREAL1: 13;
    
      per cases by
    A4,
    XBOOLE_0:def 3;
    
        suppose
    
        
    
    A17: p2 
    in L1; 
    
        then
    
        
    
    A18: ( 
    LSeg (p01,p2)) 
    c= L1 by 
    Lm22,
    TOPREAL1: 6;
    
        (
    LSeg (p1,p01)) 
    c= L2 by 
    A3,
    Lm23,
    TOPREAL1: 6;
    
        then
    
        
    
    A19: (( 
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p01,p2))) 
    c= (L2 
    /\ L1) by 
    A18,
    XBOOLE_1: 27;
    
        take P1 = ((
    LSeg (p1,p01)) 
    \/ ( 
    LSeg (p01,p2))), P2 = (( 
    LSeg (p1,p11)) 
    \/ ((L3 
    \/ L4) 
    \/ ( 
    LSeg (p00,p2)))); 
    
        
    
        
    
    A20: p01 
    in ( 
    LSeg (p01,p2)) by 
    RLTOPSP1: 68;
    
        p00
    in ( 
    LSeg (p00,p2)) by 
    RLTOPSP1: 68;
    
        then
    
        
    
    A21: 
    {}  
    <> (L3 
    /\ ( 
    LSeg (p00,p2))) by 
    Lm21,
    XBOOLE_0:def 4;
    
        p01
    in ( 
    LSeg (p1,p01)) by 
    RLTOPSP1: 68;
    
        then ((
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p01,p2))) 
    <>  
    {} by 
    A20,
    XBOOLE_0:def 4;
    
        then
    
        
    
    A22: (( 
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p01,p2))) 
    =  
    {p01} by
    A19,
    TOPREAL1: 15,
    ZFMISC_1: 33;
    
        p1
    <> p01 or p2 
    <> p01 by 
    A1;
    
        hence P1
    is_an_arc_of (p1,p2) by 
    A22,
    TOPREAL1: 12;
    
        
    
        
    
    A23: (( 
    LSeg (p1,p01)) 
    \/ ( 
    LSeg (p1,p11))) 
    = L2 by 
    A3,
    TOPREAL1: 5;
    
        
    
        
    
    A24: L4 
    is_an_arc_of (p11,p10) by 
    Lm9,
    Lm11,
    TOPREAL1: 9;
    
        L3
    is_an_arc_of (p10,p00) by 
    Lm4,
    Lm8,
    TOPREAL1: 9;
    
        then
    
        
    
    A25: (L3 
    \/ L4) 
    is_an_arc_of (p11,p00) by 
    A24,
    TOPREAL1: 2,
    TOPREAL1: 16;
    
        
    
        
    
    A26: (L3 
    /\ ( 
    LSeg (p00,p2))) 
    c=  
    {p00} by
    A17,
    Lm20,
    TOPREAL1: 6,
    TOPREAL1: 17,
    XBOOLE_1: 26;
    
        
    
        
    
    A27: (( 
    LSeg (p00,p2)) 
    \/ ( 
    LSeg (p01,p2))) 
    = L1 by 
    A17,
    TOPREAL1: 5;
    
        
    
        
    
    A28: (( 
    LSeg (p01,p2)) 
    /\ ( 
    LSeg (p00,p2))) 
    =  
    {p2} by
    A17,
    TOPREAL1: 8;
    
        
    
        
    
    A29: ( 
    LSeg (p00,p2)) 
    c= L1 by 
    A17,
    Lm20,
    TOPREAL1: 6;
    
        then
    
        
    
    A30: (L4 
    /\ ( 
    LSeg (p00,p2))) 
    =  
    {} by 
    Lm3,
    XBOOLE_1: 3,
    XBOOLE_1: 27;
    
        
    
        
    
    A31: ex q2 st q2 
    = p2 & (q2 
    `1 ) 
    =  
    0 & (q2 
    `2 ) 
    <= 1 & (q2 
    `2 ) 
    >=  
    0 by 
    A17,
    TOPREAL1: 13;
    
        
    
    A32: 
    
        now
    
          
    
          
    
    A33: (p00 
    `2 ) 
    <= (p2 
    `2 ) by 
    A31,
    EUCLID: 52;
    
          assume
    
          
    
    A34: p01 
    in (( 
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p00,p2))); 
    
          then
    
          
    
    A35: p01 
    in ( 
    LSeg (p1,p11)) by 
    XBOOLE_0:def 4;
    
          p01
    in ( 
    LSeg (p00,p2)) by 
    A34,
    XBOOLE_0:def 4;
    
          then (p01
    `2 ) 
    <= (p2 
    `2 ) by 
    A33,
    TOPREAL1: 4;
    
          then
    
          
    
    A36: (p01 
    `2 ) 
    = (p2 
    `2 ) by 
    A31,
    Lm7,
    XXREAL_0: 1;
    
          (p1
    `1 ) 
    <= (p11 
    `1 ) by 
    A13,
    A14,
    EUCLID: 52;
    
          then (p01
    `1 ) 
    = (p1 
    `1 ) by 
    A13,
    A15,
    A35,
    Lm6,
    TOPREAL1: 3;
    
          
    
          then p1
    =  
    |[(p01
    `1 ), (p01 
    `2 )]| by 
    A13,
    A16,
    Lm7,
    EUCLID: 53
    
          .= p2 by
    A31,
    A36,
    Lm6,
    EUCLID: 53;
    
          hence contradiction by
    A1;
    
        end;
    
        ((L3
    \/ L4) 
    /\ ( 
    LSeg (p00,p2))) 
    = ((L3 
    /\ ( 
    LSeg (p00,p2))) 
    \/ (L4 
    /\ ( 
    LSeg (p00,p2)))) by 
    XBOOLE_1: 23
    
        .=
    {p00} by
    A26,
    A21,
    A30,
    ZFMISC_1: 33;
    
        then
    
        
    
    A37: ((L3 
    \/ L4) 
    \/ ( 
    LSeg (p00,p2))) 
    is_an_arc_of (p11,p2) by 
    A25,
    TOPREAL1: 10;
    
        ((
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p00,p2))) 
    c= (L2 
    /\ L1) by 
    A8,
    A29,
    XBOOLE_1: 27;
    
        then
    
        
    
    A38: (( 
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p00,p2))) 
    =  
    {p01} or ((
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p00,p2))) 
    =  
    {} by 
    TOPREAL1: 15,
    ZFMISC_1: 33;
    
        
    
        
    
    A39: ( 
    LSeg (p2,p01)) 
    c= L1 by 
    A17,
    Lm22,
    TOPREAL1: 6;
    
        then
    
        
    
    A40: (( 
    LSeg (p01,p2)) 
    /\ L4) 
    =  
    {} by 
    Lm3,
    XBOOLE_1: 3,
    XBOOLE_1: 27;
    
        ((
    LSeg (p1,p11)) 
    /\ ((L3 
    \/ L4) 
    \/ ( 
    LSeg (p00,p2)))) 
    = ((( 
    LSeg (p1,p11)) 
    /\ (L3 
    \/ L4)) 
    \/ (( 
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p00,p2)))) by 
    XBOOLE_1: 23
    
        .= (((
    LSeg (p1,p11)) 
    /\ L3) 
    \/ (( 
    LSeg (p1,p11)) 
    /\ L4)) by 
    A38,
    A32,
    XBOOLE_1: 23,
    ZFMISC_1: 31
    
        .=
    {p11} by
    A9,
    A6,
    A10,
    ZFMISC_1: 33;
    
        hence P2
    is_an_arc_of (p1,p2) by 
    A37,
    TOPREAL1: 11;
    
        
    
        thus (P1
    \/ P2) 
    = (( 
    LSeg (p01,p2)) 
    \/ (( 
    LSeg (p1,p01)) 
    \/ (( 
    LSeg (p1,p11)) 
    \/ ((L3 
    \/ L4) 
    \/ ( 
    LSeg (p00,p2)))))) by 
    XBOOLE_1: 4
    
        .= ((
    LSeg (p01,p2)) 
    \/ (L2 
    \/ ((L3 
    \/ L4) 
    \/ ( 
    LSeg (p00,p2))))) by 
    A23,
    XBOOLE_1: 4
    
        .= ((
    LSeg (p01,p2)) 
    \/ ((L2 
    \/ (L3 
    \/ L4)) 
    \/ ( 
    LSeg (p00,p2)))) by 
    XBOOLE_1: 4
    
        .= (((
    LSeg (p00,p2)) 
    \/ ( 
    LSeg (p01,p2))) 
    \/ (L2 
    \/ (L3 
    \/ L4))) by 
    XBOOLE_1: 4
    
        .=
    R^2-unit_square by 
    A27,
    TOPREAL1:def 2,
    XBOOLE_1: 4;
    
        
    
        
    
    A41: 
    {p1}
    = (( 
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p1,p11))) by 
    A3,
    TOPREAL1: 8;
    
        
    
        
    
    A42: (P1 
    /\ P2) 
    = ((( 
    LSeg (p1,p01)) 
    /\ (( 
    LSeg (p1,p11)) 
    \/ ((L3 
    \/ L4) 
    \/ ( 
    LSeg (p00,p2))))) 
    \/ (( 
    LSeg (p01,p2)) 
    /\ (( 
    LSeg (p1,p11)) 
    \/ ((L3 
    \/ L4) 
    \/ ( 
    LSeg (p00,p2)))))) by 
    XBOOLE_1: 23
    
        .= ((((
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p1,p11))) 
    \/ (( 
    LSeg (p1,p01)) 
    /\ ((L3 
    \/ L4) 
    \/ ( 
    LSeg (p00,p2))))) 
    \/ (( 
    LSeg (p01,p2)) 
    /\ (( 
    LSeg (p1,p11)) 
    \/ ((L3 
    \/ L4) 
    \/ ( 
    LSeg (p00,p2)))))) by 
    XBOOLE_1: 23
    
        .= ((
    {p1}
    \/ ((( 
    LSeg (p1,p01)) 
    /\ (L3 
    \/ L4)) 
    \/ (( 
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p00,p2))))) 
    \/ (( 
    LSeg (p01,p2)) 
    /\ (( 
    LSeg (p1,p11)) 
    \/ ((L3 
    \/ L4) 
    \/ ( 
    LSeg (p00,p2)))))) by 
    A41,
    XBOOLE_1: 23
    
        .= ((
    {p1}
    \/ (((( 
    LSeg (p1,p01)) 
    /\ L3) 
    \/ (( 
    LSeg (p1,p01)) 
    /\ L4)) 
    \/ (( 
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p00,p2))))) 
    \/ (( 
    LSeg (p01,p2)) 
    /\ (( 
    LSeg (p1,p11)) 
    \/ ((L3 
    \/ L4) 
    \/ ( 
    LSeg (p00,p2)))))) by 
    XBOOLE_1: 23
    
        .= ((
    {p1}
    \/ (((( 
    LSeg (p1,p01)) 
    /\ L3) 
    \/ (( 
    LSeg (p1,p01)) 
    /\ L4)) 
    \/ (( 
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p00,p2))))) 
    \/ ((( 
    LSeg (p01,p2)) 
    /\ ( 
    LSeg (p1,p11))) 
    \/ (( 
    LSeg (p01,p2)) 
    /\ ((L3 
    \/ L4) 
    \/ ( 
    LSeg (p00,p2)))))) by 
    XBOOLE_1: 23
    
        .= ((
    {p1}
    \/ ((( 
    LSeg (p1,p01)) 
    /\ L4) 
    \/ (( 
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p00,p2))))) 
    \/ ((( 
    LSeg (p01,p2)) 
    /\ ( 
    LSeg (p1,p11))) 
    \/ ((( 
    LSeg (p01,p2)) 
    /\ (L3 
    \/ L4)) 
    \/  
    {p2}))) by
    A12,
    A28,
    XBOOLE_1: 23
    
        .= ((
    {p1}
    \/ ((( 
    LSeg (p1,p01)) 
    /\ L4) 
    \/ (( 
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p00,p2))))) 
    \/ ((( 
    LSeg (p01,p2)) 
    /\ ( 
    LSeg (p1,p11))) 
    \/ (((( 
    LSeg (p01,p2)) 
    /\ L3) 
    \/ (( 
    LSeg (p01,p2)) 
    /\ L4)) 
    \/  
    {p2}))) by
    XBOOLE_1: 23
    
        .= ((
    {p1}
    \/ ((( 
    LSeg (p1,p01)) 
    /\ L4) 
    \/ (( 
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p00,p2))))) 
    \/ ((( 
    LSeg (p01,p2)) 
    /\ ( 
    LSeg (p1,p11))) 
    \/ ((( 
    LSeg (p01,p2)) 
    /\ L3) 
    \/  
    {p2}))) by
    A40;
    
        
    
    A43: 
    
        now
    
          per cases ;
    
            suppose
    
            
    
    A44: p1 
    = p01; 
    
            then p1
    in ( 
    LSeg (p01,p2)) by 
    RLTOPSP1: 68;
    
            then
    
            
    
    A45: (( 
    LSeg (p01,p2)) 
    /\ ( 
    LSeg (p1,p11))) 
    <>  
    {} by 
    A44,
    Lm23,
    XBOOLE_0:def 4;
    
            ((
    LSeg (p01,p2)) 
    /\ ( 
    LSeg (p1,p11))) 
    c=  
    {p1} by
    A39,
    A44,
    TOPREAL1: 15,
    XBOOLE_1: 27;
    
            then
    
            
    
    A46: (( 
    LSeg (p01,p2)) 
    /\ ( 
    LSeg (p1,p11))) 
    =  
    {p1} by
    A45,
    ZFMISC_1: 33;
    
            ((
    LSeg (p1,p01)) 
    /\ L4) 
    = ( 
    {p1}
    /\ L4) by 
    A44,
    RLTOPSP1: 70;
    
            then ((
    LSeg (p1,p01)) 
    /\ L4) 
    =  
    {} by 
    A44,
    Lm1,
    Lm15;
    
            
    
            hence (P1
    /\ P2) 
    = (( 
    {p1}
    \/ ( 
    {p1}
    \/ (( 
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p00,p2))))) 
    \/ ((( 
    LSeg (p01,p2)) 
    /\ L3) 
    \/  
    {p2})) by
    A42,
    A46,
    XBOOLE_1: 4
    
            .= (((
    {p1}
    \/  
    {p1})
    \/ (( 
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p00,p2)))) 
    \/ ((( 
    LSeg (p01,p2)) 
    /\ L3) 
    \/  
    {p2})) by
    XBOOLE_1: 4
    
            .= ((
    {p1}
    \/ (( 
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p00,p2)))) 
    \/ ((( 
    LSeg (p01,p2)) 
    /\ L3) 
    \/  
    {p2}));
    
          end;
    
            suppose
    
            
    
    A47: p1 
    = p11; 
    
            then
    
            
    
    A48: (( 
    LSeg (p01,p2)) 
    /\ ( 
    LSeg (p1,p11))) 
    = (( 
    LSeg (p01,p2)) 
    /\  
    {p1}) by
    RLTOPSP1: 70;
    
             not p1
    in ( 
    LSeg (p01,p2)) by 
    A31,
    A47,
    Lm6,
    Lm10,
    TOPREAL1: 3;
    
            then ((
    LSeg (p01,p2)) 
    /\ ( 
    LSeg (p1,p11))) 
    =  
    {} by 
    A48,
    Lm1;
    
            
    
            hence (P1
    /\ P2) 
    = ((( 
    {p1}
    \/  
    {p1})
    \/ (( 
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p00,p2)))) 
    \/ ((( 
    LSeg (p01,p2)) 
    /\ L3) 
    \/  
    {p2})) by
    A42,
    A47,
    TOPREAL1: 18,
    XBOOLE_1: 4
    
            .= ((
    {p1}
    \/ (( 
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p00,p2)))) 
    \/ ((( 
    LSeg (p01,p2)) 
    /\ L3) 
    \/  
    {p2}));
    
          end;
    
            suppose
    
            
    
    A49: p1 
    <> p11 & p1 
    <> p01; 
    
            now
    
              assume p01
    in (( 
    LSeg (p01,p2)) 
    /\ ( 
    LSeg (p1,p11))); 
    
              then
    
              
    
    A50: p01 
    in ( 
    LSeg (p1,p11)) by 
    XBOOLE_0:def 4;
    
              (p1
    `1 ) 
    <= (p11 
    `1 ) by 
    A13,
    A14,
    EUCLID: 52;
    
              then (p1
    `1 ) 
    =  
    0 by 
    A13,
    A15,
    A50,
    Lm6,
    TOPREAL1: 3;
    
              hence contradiction by
    A13,
    A16,
    A49,
    EUCLID: 53;
    
            end;
    
            then
    
            
    
    A51: 
    {p01}
    <> (( 
    LSeg (p01,p2)) 
    /\ ( 
    LSeg (p1,p11))) by 
    ZFMISC_1: 31;
    
            ((
    LSeg (p01,p2)) 
    /\ ( 
    LSeg (p1,p11))) 
    c=  
    {p01} by
    A8,
    A39,
    TOPREAL1: 15,
    XBOOLE_1: 27;
    
            then
    
            
    
    A52: (( 
    LSeg (p01,p2)) 
    /\ ( 
    LSeg (p1,p11))) 
    =  
    {} by 
    A51,
    ZFMISC_1: 33;
    
            now
    
              assume p11
    in (( 
    LSeg (p1,p01)) 
    /\ L4); 
    
              then
    
              
    
    A53: p11 
    in ( 
    LSeg (p01,p1)) by 
    XBOOLE_0:def 4;
    
              (p01
    `1 ) 
    <= (p1 
    `1 ) by 
    A13,
    A15,
    EUCLID: 52;
    
              then (p11
    `1 ) 
    <= (p1 
    `1 ) by 
    A53,
    TOPREAL1: 3;
    
              then (p1
    `1 ) 
    = 1 by 
    A13,
    A14,
    Lm10,
    XXREAL_0: 1;
    
              hence contradiction by
    A13,
    A16,
    A49,
    EUCLID: 53;
    
            end;
    
            then
    
            
    
    A54: 
    {p11}
    <> (( 
    LSeg (p1,p01)) 
    /\ L4) by 
    ZFMISC_1: 31;
    
            ((
    LSeg (p1,p01)) 
    /\ L4) 
    c=  
    {p11} by
    A11,
    TOPREAL1: 18,
    XBOOLE_1: 27;
    
            then ((
    LSeg (p1,p01)) 
    /\ L4) 
    =  
    {} by 
    A54,
    ZFMISC_1: 33;
    
            hence (P1
    /\ P2) 
    = (( 
    {p1}
    \/ (( 
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p00,p2)))) 
    \/ ((( 
    LSeg (p01,p2)) 
    /\ L3) 
    \/  
    {p2})) by
    A42,
    A52;
    
          end;
    
        end;
    
        now
    
          per cases ;
    
            suppose
    
            
    
    A55: p2 
    <> p00 & p2 
    <> p01; 
    
            now
    
              assume p01
    in (( 
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p00,p2))); 
    
              then
    
              
    
    A56: p01 
    in ( 
    LSeg (p00,p2)) by 
    XBOOLE_0:def 4;
    
              (p00
    `2 ) 
    <= (p2 
    `2 ) by 
    A31,
    EUCLID: 52;
    
              then (p01
    `2 ) 
    <= (p2 
    `2 ) by 
    A56,
    TOPREAL1: 4;
    
              then (p2
    `2 ) 
    = 1 by 
    A31,
    Lm7,
    XXREAL_0: 1;
    
              hence contradiction by
    A31,
    A55,
    EUCLID: 53;
    
            end;
    
            then
    
            
    
    A57: 
    {p01}
    <> (( 
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p00,p2))) by 
    ZFMISC_1: 31;
    
            ((
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p00,p2))) 
    c= (L2 
    /\ L1) by 
    A11,
    A29,
    XBOOLE_1: 27;
    
            then
    
            
    
    A58: (( 
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p00,p2))) 
    =  
    {} by 
    A57,
    TOPREAL1: 15,
    ZFMISC_1: 33;
    
            now
    
              assume p00
    in (( 
    LSeg (p01,p2)) 
    /\ L3); 
    
              then
    
              
    
    A59: p00 
    in ( 
    LSeg (p2,p01)) by 
    XBOOLE_0:def 4;
    
              (p2
    `2 ) 
    <= (p01 
    `2 ) by 
    A31,
    EUCLID: 52;
    
              then
    0  
    = (p2 
    `2 ) by 
    A31,
    A59,
    Lm5,
    TOPREAL1: 4;
    
              hence contradiction by
    A31,
    A55,
    EUCLID: 53;
    
            end;
    
            then
    
            
    
    A60: 
    {p00}
    <> (( 
    LSeg (p01,p2)) 
    /\ L3) by 
    ZFMISC_1: 31;
    
            ((
    LSeg (p01,p2)) 
    /\ L3) 
    c=  
    {p00} by
    A39,
    TOPREAL1: 17,
    XBOOLE_1: 27;
    
            then ((
    LSeg (p01,p2)) 
    /\ L3) 
    =  
    {} by 
    A60,
    ZFMISC_1: 33;
    
            hence thesis by
    A43,
    A58,
    ENUMSET1: 1;
    
          end;
    
            suppose
    
            
    
    A61: p2 
    = p00; 
    
            then
    
            
    
    A62: (( 
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p00,p2))) 
    = (( 
    LSeg (p1,p01)) 
    /\  
    {p00}) by
    RLTOPSP1: 70;
    
             not p00
    in ( 
    LSeg (p1,p01)) by 
    A11,
    Lm5,
    Lm7,
    Lm11,
    TOPREAL1: 4;
    
            then ((
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p00,p2))) 
    =  
    {} by 
    A62,
    Lm1;
    
            hence thesis by
    A43,
    A61,
    ENUMSET1: 1,
    TOPREAL1: 17;
    
          end;
    
            suppose
    
            
    
    A63: p2 
    = p01; 
    
            then p2
    in ( 
    LSeg (p1,p01)) by 
    RLTOPSP1: 68;
    
            then
    
            
    
    A64: 
    {}  
    <> (( 
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p00,p2))) by 
    A63,
    Lm22,
    XBOOLE_0:def 4;
    
            ((
    LSeg (p01,p2)) 
    /\ L3) 
    = ( 
    {p01}
    /\ L3) by 
    A63,
    RLTOPSP1: 70;
    
            then
    
            
    
    A65: (( 
    LSeg (p01,p2)) 
    /\ L3) 
    =  
    {} by 
    Lm1,
    Lm14;
    
            ((
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p00,p2))) 
    c= (L2 
    /\ L1) by 
    A11,
    A29,
    XBOOLE_1: 27;
    
            then ((
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p00,p2))) 
    =  
    {p2} by
    A63,
    A64,
    TOPREAL1: 15,
    ZFMISC_1: 33;
    
            
    
            hence (P1
    /\ P2) 
    = ( 
    {p1}
    \/ ( 
    {p2}
    \/  
    {p2})) by
    A43,
    A65,
    XBOOLE_1: 4
    
            .=
    {p1, p2} by
    ENUMSET1: 1;
    
          end;
    
        end;
    
        hence thesis;
    
      end;
    
        suppose
    
        
    
    A66: p2 
    in L2; 
    
        
    
        
    
    A67: q1 
    =  
    |[(q1
    `1 ), (q1 
    `2 )]| by 
    EUCLID: 53;
    
        
    
        
    
    A68: ( 
    LSeg (p1,p2)) 
    c= L2 by 
    A3,
    A66,
    TOPREAL1: 6;
    
        consider q such that
    
        
    
    A69: q 
    = p2 and 
    
        
    
    A70: (q 
    `1 ) 
    <= 1 and 
    
        
    
    A71: (q 
    `1 ) 
    >=  
    0 and 
    
        
    
    A72: (q 
    `2 ) 
    = 1 by 
    A66,
    TOPREAL1: 13;
    
        
    
        
    
    A73: q 
    =  
    |[(q
    `1 ), (q 
    `2 )]| by 
    EUCLID: 53;
    
        now
    
          per cases by
    A1,
    A13,
    A16,
    A69,
    A72,
    A67,
    A73,
    XXREAL_0: 1;
    
            suppose
    
            
    
    A74: (q1 
    `1 ) 
    < (q 
    `1 ); 
    
            
    
            
    
    A75: (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p11,p2))) 
    c=  
    {p2}
    
            proof
    
              let a be
    object;
    
              assume
    
              
    
    A76: a 
    in (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p11,p2))); 
    
              then
    
              reconsider p = a as
    Point of ( 
    TOP-REAL 2); 
    
              
    
              
    
    A77: p 
    in ( 
    LSeg (p2,p11)) by 
    A76,
    XBOOLE_0:def 4;
    
              (p2
    `1 ) 
    <= (p11 
    `1 ) by 
    A69,
    A70,
    EUCLID: 52;
    
              then
    
              
    
    A78: (p2 
    `1 ) 
    <= (p 
    `1 ) by 
    A77,
    TOPREAL1: 3;
    
              
    
              
    
    A79: p 
    in ( 
    LSeg (p1,p2)) by 
    A76,
    XBOOLE_0:def 4;
    
              then
    
              
    
    A80: (p 
    `2 ) 
    <= (p2 
    `2 ) by 
    A13,
    A16,
    A69,
    A72,
    TOPREAL1: 4;
    
              (p
    `1 ) 
    <= (p2 
    `1 ) by 
    A13,
    A69,
    A74,
    A79,
    TOPREAL1: 3;
    
              then
    
              
    
    A81: (p2 
    `1 ) 
    = (p 
    `1 ) by 
    A78,
    XXREAL_0: 1;
    
              (p1
    `2 ) 
    <= (p 
    `2 ) by 
    A13,
    A16,
    A69,
    A72,
    A79,
    TOPREAL1: 4;
    
              then (p
    `2 ) 
    = 1 by 
    A13,
    A16,
    A69,
    A72,
    A80,
    XXREAL_0: 1;
    
              
    
              then p
    =  
    |[(p2
    `1 ), 1]| by 
    A81,
    EUCLID: 53
    
              .= p2 by
    A69,
    A72,
    EUCLID: 53;
    
              hence thesis by
    TARSKI:def 1;
    
            end;
    
            (L3
    /\ L2) 
    =  
    {} by 
    TOPREAL1: 19,
    XBOOLE_0:def 7;
    
            then
    
            
    
    A82: (( 
    LSeg (p1,p01)) 
    /\ L3) 
    =  
    {} by 
    A11,
    XBOOLE_1: 3,
    XBOOLE_1: 26;
    
            
    
    A83: 
    
            now
    
              set a = the
    Element of (( 
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p11,p2))); 
    
              assume
    
              
    
    A84: (( 
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p11,p2))) 
    <>  
    {} ; 
    
              then
    
              reconsider p = a as
    Point of ( 
    TOP-REAL 2) by 
    TARSKI:def 3;
    
              
    
              
    
    A85: p 
    in ( 
    LSeg (p01,p1)) by 
    A84,
    XBOOLE_0:def 4;
    
              
    
              
    
    A86: p 
    in ( 
    LSeg (p2,p11)) by 
    A84,
    XBOOLE_0:def 4;
    
              (p2
    `1 ) 
    <= (p11 
    `1 ) by 
    A69,
    A70,
    EUCLID: 52;
    
              then
    
              
    
    A87: (p2 
    `1 ) 
    <= (p 
    `1 ) by 
    A86,
    TOPREAL1: 3;
    
              (p01
    `1 ) 
    <= (p1 
    `1 ) by 
    A13,
    A15,
    EUCLID: 52;
    
              then (p
    `1 ) 
    <= (p1 
    `1 ) by 
    A85,
    TOPREAL1: 3;
    
              hence contradiction by
    A13,
    A69,
    A74,
    A87,
    XXREAL_0: 2;
    
            end;
    
            
    
            
    
    A88: ((L1 
    \/ L3) 
    /\ L4) 
    = ((L1 
    /\ L4) 
    \/ (L3 
    /\ L4)) by 
    XBOOLE_1: 23
    
            .=
    {p10} by
    Lm3,
    TOPREAL1: 16;
    
            (L1
    \/ L3) 
    is_an_arc_of (p01,p10) by 
    Lm5,
    Lm7,
    TOPREAL1: 9,
    TOPREAL1: 10,
    TOPREAL1: 17;
    
            then
    
            
    
    A89: ((L1 
    \/ L3) 
    \/ L4) 
    is_an_arc_of (p01,p11) by 
    A88,
    TOPREAL1: 10;
    
            
    
            
    
    A90: (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p1,p01))) 
    c=  
    {p1}
    
            proof
    
              let a be
    object;
    
              assume
    
              
    
    A91: a 
    in (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p1,p01))); 
    
              then
    
              reconsider p = a as
    Point of ( 
    TOP-REAL 2); 
    
              
    
              
    
    A92: p 
    in ( 
    LSeg (p01,p1)) by 
    A91,
    XBOOLE_0:def 4;
    
              (p01
    `1 ) 
    <= (p1 
    `1 ) by 
    A13,
    A15,
    EUCLID: 52;
    
              then
    
              
    
    A93: (p 
    `1 ) 
    <= (p1 
    `1 ) by 
    A92,
    TOPREAL1: 3;
    
              
    
              
    
    A94: p 
    in ( 
    LSeg (p1,p2)) by 
    A91,
    XBOOLE_0:def 4;
    
              then
    
              
    
    A95: (p 
    `2 ) 
    <= (p2 
    `2 ) by 
    A13,
    A16,
    A69,
    A72,
    TOPREAL1: 4;
    
              (p1
    `1 ) 
    <= (p 
    `1 ) by 
    A13,
    A69,
    A74,
    A94,
    TOPREAL1: 3;
    
              then
    
              
    
    A96: (p1 
    `1 ) 
    = (p 
    `1 ) by 
    A93,
    XXREAL_0: 1;
    
              (p1
    `2 ) 
    <= (p 
    `2 ) by 
    A13,
    A16,
    A69,
    A72,
    A94,
    TOPREAL1: 4;
    
              then (p
    `2 ) 
    = 1 by 
    A13,
    A16,
    A69,
    A72,
    A95,
    XXREAL_0: 1;
    
              
    
              then p
    =  
    |[(p1
    `1 ), 1]| by 
    A96,
    EUCLID: 53
    
              .= p1 by
    A13,
    A16,
    EUCLID: 53;
    
              hence thesis by
    TARSKI:def 1;
    
            end;
    
            
    
            
    
    A97: (( 
    LSeg (p1,p2)) 
    /\ L1) 
    c= (L2 
    /\ L1) by 
    A3,
    A66,
    TOPREAL1: 6,
    XBOOLE_1: 26;
    
            now
    
              assume p11
    in (( 
    LSeg (p1,p01)) 
    /\ L4); 
    
              then
    
              
    
    A98: p11 
    in ( 
    LSeg (p01,p1)) by 
    XBOOLE_0:def 4;
    
              (p01
    `1 ) 
    <= (p1 
    `1 ) by 
    A13,
    A15,
    EUCLID: 52;
    
              then (p11
    `1 ) 
    <= (p1 
    `1 ) by 
    A98,
    TOPREAL1: 3;
    
              hence contradiction by
    A13,
    A14,
    A70,
    A74,
    Lm10,
    XXREAL_0: 1;
    
            end;
    
            then
    
            
    
    A99: 
    {p11}
    <> (( 
    LSeg (p1,p01)) 
    /\ L4) by 
    ZFMISC_1: 31;
    
            ((
    LSeg (p1,p01)) 
    /\ L4) 
    c=  
    {p11} by
    A3,
    Lm23,
    TOPREAL1: 6,
    TOPREAL1: 18,
    XBOOLE_1: 26;
    
            then
    
            
    
    A100: (( 
    LSeg (p1,p01)) 
    /\ L4) 
    =  
    {} by 
    A99,
    ZFMISC_1: 33;
    
            p01
    in ( 
    LSeg (p1,p01)) by 
    RLTOPSP1: 68;
    
            then
    
            
    
    A101: (( 
    LSeg (p1,p01)) 
    /\ L1) 
    <>  
    {} by 
    Lm22,
    XBOOLE_0:def 4;
    
            now
    
              assume p01
    in (L1 
    /\ ( 
    LSeg (p11,p2))); 
    
              then
    
              
    
    A102: p01 
    in ( 
    LSeg (p2,p11)) by 
    XBOOLE_0:def 4;
    
              (p2
    `1 ) 
    <= (p11 
    `1 ) by 
    A69,
    A70,
    EUCLID: 52;
    
              hence contradiction by
    A15,
    A69,
    A74,
    A102,
    Lm6,
    TOPREAL1: 3;
    
            end;
    
            then
    
            
    
    A103: 
    {p01}
    <> (L1 
    /\ ( 
    LSeg (p11,p2))) by 
    ZFMISC_1: 31;
    
            (L1
    /\ ( 
    LSeg (p11,p2))) 
    c=  
    {p01} by
    A66,
    Lm26,
    TOPREAL1: 6,
    TOPREAL1: 15,
    XBOOLE_1: 26;
    
            then
    
            
    
    A104: (L1 
    /\ ( 
    LSeg (p11,p2))) 
    =  
    {} by 
    A103,
    ZFMISC_1: 33;
    
            take P1 = (
    LSeg (p1,p2)), P2 = (( 
    LSeg (p1,p01)) 
    \/ (((L1 
    \/ L3) 
    \/ L4) 
    \/ ( 
    LSeg (p11,p2)))); 
    
            
    
            
    
    A105: p1 
    in ( 
    LSeg (p1,p01)) by 
    RLTOPSP1: 68;
    
            
    
            
    
    A106: (( 
    LSeg (p1,p01)) 
    /\ L1) 
    c= (L2 
    /\ L1) by 
    A3,
    Lm23,
    TOPREAL1: 6,
    XBOOLE_1: 26;
    
            p11
    in ( 
    LSeg (p11,p2)) by 
    RLTOPSP1: 68;
    
            then
    
            
    
    A107: (L4 
    /\ ( 
    LSeg (p11,p2))) 
    <>  
    {} by 
    Lm27,
    XBOOLE_0:def 4;
    
            (L4
    /\ ( 
    LSeg (p11,p2))) 
    c= (L4 
    /\ L2) by 
    A66,
    Lm26,
    TOPREAL1: 6,
    XBOOLE_1: 26;
    
            then
    
            
    
    A108: (L4 
    /\ ( 
    LSeg (p11,p2))) 
    =  
    {p11} by
    A107,
    TOPREAL1: 18,
    ZFMISC_1: 33;
    
            thus P1
    is_an_arc_of (p1,p2) by 
    A1,
    TOPREAL1: 9;
    
            
    
            
    
    A109: (L3 
    /\ L2) 
    =  
    {} by 
    TOPREAL1: 19,
    XBOOLE_0:def 7;
    
            (L3
    /\ ( 
    LSeg (p11,p2))) 
    c= (L3 
    /\ L2) by 
    A66,
    Lm26,
    TOPREAL1: 6,
    XBOOLE_1: 26;
    
            then
    
            
    
    A110: (L3 
    /\ ( 
    LSeg (p11,p2))) 
    =  
    {} by 
    A109,
    XBOOLE_1: 3;
    
            (((L1
    \/ L3) 
    \/ L4) 
    /\ ( 
    LSeg (p11,p2))) 
    = (((L1 
    \/ L3) 
    /\ ( 
    LSeg (p11,p2))) 
    \/ (L4 
    /\ ( 
    LSeg (p11,p2)))) by 
    XBOOLE_1: 23
    
            .= (((L1
    /\ ( 
    LSeg (p11,p2))) 
    \/ (L3 
    /\ ( 
    LSeg (p11,p2)))) 
    \/  
    {p11}) by
    A108,
    XBOOLE_1: 23
    
            .=
    {p11} by
    A104,
    A110;
    
            then
    
            
    
    A111: (((L1 
    \/ L3) 
    \/ L4) 
    \/ ( 
    LSeg (p11,p2))) 
    is_an_arc_of (p01,p2) by 
    A89,
    TOPREAL1: 10;
    
            ((
    LSeg (p1,p01)) 
    /\ (((L1 
    \/ L3) 
    \/ L4) 
    \/ ( 
    LSeg (p11,p2)))) 
    = ((( 
    LSeg (p1,p01)) 
    /\ ((L1 
    \/ L3) 
    \/ L4)) 
    \/ (( 
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p11,p2)))) by 
    XBOOLE_1: 23
    
            .= (((
    LSeg (p1,p01)) 
    /\ (L1 
    \/ L3)) 
    \/ (( 
    LSeg (p1,p01)) 
    /\ L4)) by 
    A83,
    XBOOLE_1: 23
    
            .= (((
    LSeg (p1,p01)) 
    /\ L1) 
    \/ (( 
    LSeg (p1,p01)) 
    /\ L3)) by 
    A100,
    XBOOLE_1: 23
    
            .=
    {p01} by
    A82,
    A106,
    A101,
    TOPREAL1: 15,
    ZFMISC_1: 33;
    
            hence P2
    is_an_arc_of (p1,p2) by 
    A111,
    TOPREAL1: 11;
    
            
    
            thus (P1
    \/ P2) 
    = ((( 
    LSeg (p01,p1)) 
    \/ ( 
    LSeg (p1,p2))) 
    \/ (((L1 
    \/ L3) 
    \/ L4) 
    \/ ( 
    LSeg (p11,p2)))) by 
    XBOOLE_1: 4
    
            .= ((((
    LSeg (p01,p1)) 
    \/ ( 
    LSeg (p1,p2))) 
    \/ ( 
    LSeg (p2,p11))) 
    \/ ((L1 
    \/ L3) 
    \/ L4)) by 
    XBOOLE_1: 4
    
            .= (L2
    \/ ((L1 
    \/ L3) 
    \/ L4)) by 
    A3,
    A66,
    TOPREAL1: 7
    
            .= (L2
    \/ (L1 
    \/ (L3 
    \/ L4))) by 
    XBOOLE_1: 4
    
            .=
    R^2-unit_square by 
    TOPREAL1:def 2,
    XBOOLE_1: 4;
    
            
    
            
    
    A112: p2 
    in ( 
    LSeg (p11,p2)) by 
    RLTOPSP1: 68;
    
            p2
    in ( 
    LSeg (p1,p2)) by 
    RLTOPSP1: 68;
    
            then p2
    in (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p11,p2))) by 
    A112,
    XBOOLE_0:def 4;
    
            then
    {p2}
    c= (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p11,p2))) by 
    ZFMISC_1: 31;
    
            then
    
            
    
    A113: (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p11,p2))) 
    =  
    {p2} by
    A75,
    XBOOLE_0:def 10;
    
            (L3
    /\ L2) 
    =  
    {} by 
    TOPREAL1: 19,
    XBOOLE_0:def 7;
    
            then
    
            
    
    A114: (( 
    LSeg (p1,p2)) 
    /\ L3) 
    =  
    {} by 
    A68,
    XBOOLE_1: 3,
    XBOOLE_1: 26;
    
            p1
    in ( 
    LSeg (p1,p2)) by 
    RLTOPSP1: 68;
    
            then p1
    in (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p1,p01))) by 
    A105,
    XBOOLE_0:def 4;
    
            then
    {p1}
    c= (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p1,p01))) by 
    ZFMISC_1: 31;
    
            then
    
            
    
    A115: (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p1,p01))) 
    =  
    {p1} by
    A90,
    XBOOLE_0:def 10;
    
            
    
            
    
    A116: (P1 
    /\ P2) 
    = ((( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p1,p01))) 
    \/ (( 
    LSeg (p1,p2)) 
    /\ (((L1 
    \/ L3) 
    \/ L4) 
    \/ ( 
    LSeg (p11,p2))))) by 
    XBOOLE_1: 23
    
            .= (
    {p1}
    \/ ((( 
    LSeg (p1,p2)) 
    /\ ((L1 
    \/ L3) 
    \/ L4)) 
    \/  
    {p2})) by
    A115,
    A113,
    XBOOLE_1: 23
    
            .= (
    {p1}
    \/ (((( 
    LSeg (p1,p2)) 
    /\ (L1 
    \/ L3)) 
    \/ (( 
    LSeg (p1,p2)) 
    /\ L4)) 
    \/  
    {p2})) by
    XBOOLE_1: 23
    
            .= (
    {p1}
    \/ ((((( 
    LSeg (p1,p2)) 
    /\ L1) 
    \/ (( 
    LSeg (p1,p2)) 
    /\ L3)) 
    \/ (( 
    LSeg (p1,p2)) 
    /\ L4)) 
    \/  
    {p2})) by
    XBOOLE_1: 23
    
            .= (
    {p1}
    \/ ((( 
    LSeg (p1,p2)) 
    /\ L1) 
    \/ ((( 
    LSeg (p1,p2)) 
    /\ L4) 
    \/  
    {p2}))) by
    A114,
    XBOOLE_1: 4
    
            .= ((
    {p1}
    \/ (( 
    LSeg (p1,p2)) 
    /\ L1)) 
    \/ ((( 
    LSeg (p1,p2)) 
    /\ L4) 
    \/  
    {p2})) by
    XBOOLE_1: 4;
    
            
    
    A117: 
    
            now
    
              per cases ;
    
                suppose
    
                
    
    A118: p1 
    = p01; 
    
                p1
    in ( 
    LSeg (p1,p2)) by 
    RLTOPSP1: 68;
    
                then ((
    LSeg (p1,p2)) 
    /\ L1) 
    <>  
    {} by 
    A118,
    Lm22,
    XBOOLE_0:def 4;
    
                then ((
    LSeg (p1,p2)) 
    /\ L1) 
    =  
    {p1} by
    A97,
    A118,
    TOPREAL1: 15,
    ZFMISC_1: 33;
    
                hence (P1
    /\ P2) 
    = ( 
    {p1}
    \/ ((( 
    LSeg (p1,p2)) 
    /\ L4) 
    \/  
    {p2})) by
    A116;
    
              end;
    
                suppose
    
                
    
    A119: p1 
    <> p01; 
    
                now
    
                  assume p01
    in (( 
    LSeg (p1,p2)) 
    /\ L1); 
    
                  then p01
    in ( 
    LSeg (p1,p2)) by 
    XBOOLE_0:def 4;
    
                  then (p1
    `1 ) 
    =  
    0 by 
    A13,
    A15,
    A69,
    A74,
    Lm6,
    TOPREAL1: 3;
    
                  hence contradiction by
    A13,
    A16,
    A119,
    EUCLID: 53;
    
                end;
    
                then
    {p01}
    <> (( 
    LSeg (p1,p2)) 
    /\ L1) by 
    ZFMISC_1: 31;
    
                then ((
    LSeg (p1,p2)) 
    /\ L1) 
    =  
    {} by 
    A97,
    TOPREAL1: 15,
    ZFMISC_1: 33;
    
                hence (P1
    /\ P2) 
    = ( 
    {p1}
    \/ ((( 
    LSeg (p1,p2)) 
    /\ L4) 
    \/  
    {p2})) by
    A116;
    
              end;
    
            end;
    
            
    
            
    
    A120: (( 
    LSeg (p1,p2)) 
    /\ L4) 
    c=  
    {p11} by
    A3,
    A66,
    TOPREAL1: 6,
    TOPREAL1: 18,
    XBOOLE_1: 26;
    
            now
    
              per cases ;
    
                suppose
    
                
    
    A121: p2 
    = p11; 
    
                p2
    in ( 
    LSeg (p1,p2)) by 
    RLTOPSP1: 68;
    
                then ((
    LSeg (p1,p2)) 
    /\ L4) 
    <>  
    {} by 
    A121,
    Lm27,
    XBOOLE_0:def 4;
    
                then ((
    LSeg (p1,p2)) 
    /\ L4) 
    =  
    {p2} by
    A120,
    A121,
    ZFMISC_1: 33;
    
                hence (P1
    /\ P2) 
    =  
    {p1, p2} by
    A117,
    ENUMSET1: 1;
    
              end;
    
                suppose
    
                
    
    A122: p2 
    <> p11; 
    
                now
    
                  assume p11
    in (( 
    LSeg (p1,p2)) 
    /\ L4); 
    
                  then p11
    in ( 
    LSeg (p1,p2)) by 
    XBOOLE_0:def 4;
    
                  then (p11
    `1 ) 
    <= (p2 
    `1 ) by 
    A13,
    A69,
    A74,
    TOPREAL1: 3;
    
                  then (p2
    `1 ) 
    = 1 by 
    A69,
    A70,
    Lm10,
    XXREAL_0: 1;
    
                  hence contradiction by
    A69,
    A72,
    A122,
    EUCLID: 53;
    
                end;
    
                then
    {p11}
    <> (( 
    LSeg (p1,p2)) 
    /\ L4) by 
    ZFMISC_1: 31;
    
                then ((
    LSeg (p1,p2)) 
    /\ L4) 
    =  
    {} by 
    A120,
    ZFMISC_1: 33;
    
                hence (P1
    /\ P2) 
    =  
    {p1, p2} by
    A117,
    ENUMSET1: 1;
    
              end;
    
            end;
    
            hence (P1
    /\ P2) 
    =  
    {p1, p2};
    
          end;
    
            suppose
    
            
    
    A123: (q 
    `1 ) 
    < (q1 
    `1 ); 
    
            
    
            
    
    A124: (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p01,p2))) 
    c=  
    {p2}
    
            proof
    
              let a be
    object;
    
              assume
    
              
    
    A125: a 
    in (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p01,p2))); 
    
              then
    
              reconsider p = a as
    Point of ( 
    TOP-REAL 2); 
    
              
    
              
    
    A126: p 
    in ( 
    LSeg (p01,p2)) by 
    A125,
    XBOOLE_0:def 4;
    
              (p01
    `1 ) 
    <= (p2 
    `1 ) by 
    A69,
    A71,
    EUCLID: 52;
    
              then
    
              
    
    A127: (p 
    `1 ) 
    <= (p2 
    `1 ) by 
    A126,
    TOPREAL1: 3;
    
              
    
              
    
    A128: p 
    in ( 
    LSeg (p2,p1)) by 
    A125,
    XBOOLE_0:def 4;
    
              then
    
              
    
    A129: (p 
    `2 ) 
    <= (p1 
    `2 ) by 
    A13,
    A16,
    A69,
    A72,
    TOPREAL1: 4;
    
              (p2
    `1 ) 
    <= (p 
    `1 ) by 
    A13,
    A69,
    A123,
    A128,
    TOPREAL1: 3;
    
              then
    
              
    
    A130: (p2 
    `1 ) 
    = (p 
    `1 ) by 
    A127,
    XXREAL_0: 1;
    
              (p2
    `2 ) 
    <= (p 
    `2 ) by 
    A13,
    A16,
    A69,
    A72,
    A128,
    TOPREAL1: 4;
    
              then (p
    `2 ) 
    = 1 by 
    A13,
    A16,
    A69,
    A72,
    A129,
    XXREAL_0: 1;
    
              
    
              then p
    =  
    |[(p2
    `1 ), 1]| by 
    A130,
    EUCLID: 53
    
              .= p2 by
    A69,
    A72,
    EUCLID: 53;
    
              hence thesis by
    TARSKI:def 1;
    
            end;
    
            (L3
    /\ L2) 
    =  
    {} by 
    TOPREAL1: 19,
    XBOOLE_0:def 7;
    
            then
    
            
    
    A131: (( 
    LSeg (p1,p11)) 
    /\ L3) 
    =  
    {} by 
    A8,
    XBOOLE_1: 3,
    XBOOLE_1: 26;
    
            
    
    A132: 
    
            now
    
              set a = the
    Element of (( 
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p01,p2))); 
    
              assume
    
              
    
    A133: (( 
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p01,p2))) 
    <>  
    {} ; 
    
              then
    
              reconsider p = a as
    Point of ( 
    TOP-REAL 2) by 
    TARSKI:def 3;
    
              
    
              
    
    A134: p 
    in ( 
    LSeg (p1,p11)) by 
    A133,
    XBOOLE_0:def 4;
    
              
    
              
    
    A135: p 
    in ( 
    LSeg (p01,p2)) by 
    A133,
    XBOOLE_0:def 4;
    
              (p01
    `1 ) 
    <= (p2 
    `1 ) by 
    A69,
    A71,
    EUCLID: 52;
    
              then
    
              
    
    A136: (p 
    `1 ) 
    <= (p2 
    `1 ) by 
    A135,
    TOPREAL1: 3;
    
              (p1
    `1 ) 
    <= (p11 
    `1 ) by 
    A13,
    A14,
    EUCLID: 52;
    
              then (p1
    `1 ) 
    <= (p 
    `1 ) by 
    A134,
    TOPREAL1: 3;
    
              hence contradiction by
    A13,
    A69,
    A123,
    A136,
    XXREAL_0: 2;
    
            end;
    
            
    
            
    
    A137: ((L4 
    \/ L3) 
    /\ L1) 
    = ((L1 
    /\ L4) 
    \/ (L3 
    /\ L1)) by 
    XBOOLE_1: 23
    
            .=
    {p00} by
    Lm3,
    TOPREAL1: 17;
    
            (L4
    \/ L3) 
    is_an_arc_of (p11,p00) by 
    Lm9,
    Lm11,
    TOPREAL1: 9,
    TOPREAL1: 10,
    TOPREAL1: 16;
    
            then
    
            
    
    A138: ((L4 
    \/ L3) 
    \/ L1) 
    is_an_arc_of (p11,p01) by 
    A137,
    TOPREAL1: 10;
    
            now
    
              assume p11
    in (L4 
    /\ ( 
    LSeg (p01,p2))); 
    
              then
    
              
    
    A139: p11 
    in ( 
    LSeg (p01,p2)) by 
    XBOOLE_0:def 4;
    
              (p01
    `1 ) 
    <= (p2 
    `1 ) by 
    A69,
    A71,
    EUCLID: 52;
    
              then (p11
    `1 ) 
    <= (p2 
    `1 ) by 
    A139,
    TOPREAL1: 3;
    
              hence contradiction by
    A14,
    A69,
    A70,
    A123,
    Lm10,
    XXREAL_0: 1;
    
            end;
    
            then
    
            
    
    A140: 
    {p11}
    <> (L4 
    /\ ( 
    LSeg (p01,p2))) by 
    ZFMISC_1: 31;
    
            (L4
    /\ ( 
    LSeg (p01,p2))) 
    c= (L4 
    /\ L2) by 
    A66,
    Lm23,
    TOPREAL1: 6,
    XBOOLE_1: 26;
    
            then
    
            
    
    A141: (L4 
    /\ ( 
    LSeg (p01,p2))) 
    =  
    {} by 
    A140,
    TOPREAL1: 18,
    ZFMISC_1: 33;
    
            p11
    in ( 
    LSeg (p1,p11)) by 
    RLTOPSP1: 68;
    
            then
    
            
    
    A142: (( 
    LSeg (p1,p11)) 
    /\ L4) 
    <>  
    {} by 
    Lm27,
    XBOOLE_0:def 4;
    
            now
    
              assume p01
    in (( 
    LSeg (p1,p11)) 
    /\ L1); 
    
              then
    
              
    
    A143: p01 
    in ( 
    LSeg (p1,p11)) by 
    XBOOLE_0:def 4;
    
              (p1
    `1 ) 
    <= (p11 
    `1 ) by 
    A13,
    A14,
    EUCLID: 52;
    
              hence contradiction by
    A13,
    A71,
    A123,
    A143,
    Lm6,
    TOPREAL1: 3;
    
            end;
    
            then
    
            
    
    A144: 
    {p01}
    <> (( 
    LSeg (p1,p11)) 
    /\ L1) by 
    ZFMISC_1: 31;
    
            ((
    LSeg (p1,p11)) 
    /\ L1) 
    c= (L2 
    /\ L1) by 
    A3,
    Lm26,
    TOPREAL1: 6,
    XBOOLE_1: 26;
    
            then
    
            
    
    A145: (( 
    LSeg (p1,p11)) 
    /\ L1) 
    =  
    {} by 
    A144,
    TOPREAL1: 15,
    ZFMISC_1: 33;
    
            (L3
    /\ L2) 
    =  
    {} by 
    TOPREAL1: 19,
    XBOOLE_0:def 7;
    
            then
    
            
    
    A146: (( 
    LSeg (p1,p2)) 
    /\ L3) 
    =  
    {} by 
    A68,
    XBOOLE_1: 3,
    XBOOLE_1: 26;
    
            
    
            
    
    A147: (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p1,p11))) 
    c=  
    {p1}
    
            proof
    
              let a be
    object;
    
              assume
    
              
    
    A148: a 
    in (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p1,p11))); 
    
              then
    
              reconsider p = a as
    Point of ( 
    TOP-REAL 2); 
    
              
    
              
    
    A149: p 
    in ( 
    LSeg (p1,p11)) by 
    A148,
    XBOOLE_0:def 4;
    
              (p1
    `1 ) 
    <= (p11 
    `1 ) by 
    A13,
    A14,
    EUCLID: 52;
    
              then
    
              
    
    A150: (p1 
    `1 ) 
    <= (p 
    `1 ) by 
    A149,
    TOPREAL1: 3;
    
              
    
              
    
    A151: p 
    in ( 
    LSeg (p2,p1)) by 
    A148,
    XBOOLE_0:def 4;
    
              then
    
              
    
    A152: (p 
    `2 ) 
    <= (p1 
    `2 ) by 
    A13,
    A16,
    A69,
    A72,
    TOPREAL1: 4;
    
              (p
    `1 ) 
    <= (p1 
    `1 ) by 
    A13,
    A69,
    A123,
    A151,
    TOPREAL1: 3;
    
              then
    
              
    
    A153: (p1 
    `1 ) 
    = (p 
    `1 ) by 
    A150,
    XXREAL_0: 1;
    
              (p2
    `2 ) 
    <= (p 
    `2 ) by 
    A13,
    A16,
    A69,
    A72,
    A151,
    TOPREAL1: 4;
    
              then (p
    `2 ) 
    = 1 by 
    A13,
    A16,
    A69,
    A72,
    A152,
    XXREAL_0: 1;
    
              
    
              then p
    =  
    |[(p1
    `1 ), 1]| by 
    A153,
    EUCLID: 53
    
              .= p1 by
    A13,
    A16,
    EUCLID: 53;
    
              hence thesis by
    TARSKI:def 1;
    
            end;
    
            
    
            
    
    A154: (( 
    LSeg (p1,p11)) 
    /\ L4) 
    c=  
    {p11} by
    A3,
    Lm26,
    TOPREAL1: 6,
    TOPREAL1: 18,
    XBOOLE_1: 26;
    
            p01
    in ( 
    LSeg (p01,p2)) by 
    RLTOPSP1: 68;
    
            then
    
            
    
    A155: (L1 
    /\ ( 
    LSeg (p01,p2))) 
    <>  
    {} by 
    Lm22,
    XBOOLE_0:def 4;
    
            (L1
    /\ ( 
    LSeg (p01,p2))) 
    c=  
    {p01} by
    A66,
    Lm23,
    TOPREAL1: 6,
    TOPREAL1: 15,
    XBOOLE_1: 26;
    
            then
    
            
    
    A156: (L1 
    /\ ( 
    LSeg (p01,p2))) 
    =  
    {p01} by
    A155,
    ZFMISC_1: 33;
    
            take P1 = (
    LSeg (p1,p2)), P2 = (( 
    LSeg (p1,p11)) 
    \/ (((L4 
    \/ L3) 
    \/ L1) 
    \/ ( 
    LSeg (p01,p2)))); 
    
            
    
            
    
    A157: p1 
    in ( 
    LSeg (p1,p11)) by 
    RLTOPSP1: 68;
    
            thus P1
    is_an_arc_of (p1,p2) by 
    A1,
    TOPREAL1: 9;
    
            
    
            
    
    A158: (L3 
    /\ L2) 
    =  
    {} by 
    TOPREAL1: 19,
    XBOOLE_0:def 7;
    
            (L3
    /\ ( 
    LSeg (p01,p2))) 
    c= (L3 
    /\ L2) by 
    A66,
    Lm23,
    TOPREAL1: 6,
    XBOOLE_1: 26;
    
            then
    
            
    
    A159: (L3 
    /\ ( 
    LSeg (p01,p2))) 
    =  
    {} by 
    A158,
    XBOOLE_1: 3;
    
            (((L4
    \/ L3) 
    \/ L1) 
    /\ ( 
    LSeg (p01,p2))) 
    = (((L4 
    \/ L3) 
    /\ ( 
    LSeg (p01,p2))) 
    \/ (L1 
    /\ ( 
    LSeg (p01,p2)))) by 
    XBOOLE_1: 23
    
            .= (((L4
    /\ ( 
    LSeg (p01,p2))) 
    \/ (L3 
    /\ ( 
    LSeg (p01,p2)))) 
    \/  
    {p01}) by
    A156,
    XBOOLE_1: 23
    
            .=
    {p01} by
    A141,
    A159;
    
            then
    
            
    
    A160: (((L4 
    \/ L3) 
    \/ L1) 
    \/ ( 
    LSeg (p01,p2))) 
    is_an_arc_of (p11,p2) by 
    A138,
    TOPREAL1: 10;
    
            ((
    LSeg (p1,p11)) 
    /\ (((L4 
    \/ L3) 
    \/ L1) 
    \/ ( 
    LSeg (p01,p2)))) 
    = ((( 
    LSeg (p1,p11)) 
    /\ ((L4 
    \/ L3) 
    \/ L1)) 
    \/ (( 
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p01,p2)))) by 
    XBOOLE_1: 23
    
            .= (((
    LSeg (p1,p11)) 
    /\ (L4 
    \/ L3)) 
    \/ (( 
    LSeg (p1,p11)) 
    /\ L1)) by 
    A132,
    XBOOLE_1: 23
    
            .= (((
    LSeg (p1,p11)) 
    /\ L4) 
    \/ (( 
    LSeg (p1,p11)) 
    /\ L3)) by 
    A145,
    XBOOLE_1: 23
    
            .=
    {p11} by
    A131,
    A154,
    A142,
    ZFMISC_1: 33;
    
            hence P2
    is_an_arc_of (p1,p2) by 
    A160,
    TOPREAL1: 11;
    
            
    
            thus (P1
    \/ P2) 
    = ((( 
    LSeg (p2,p1)) 
    \/ ( 
    LSeg (p1,p11))) 
    \/ (((L4 
    \/ L3) 
    \/ L1) 
    \/ ( 
    LSeg (p01,p2)))) by 
    XBOOLE_1: 4
    
            .= (((
    LSeg (p01,p2)) 
    \/ (( 
    LSeg (p2,p1)) 
    \/ ( 
    LSeg (p1,p11)))) 
    \/ ((L4 
    \/ L3) 
    \/ L1)) by 
    XBOOLE_1: 4
    
            .= (L2
    \/ ((L4 
    \/ L3) 
    \/ L1)) by 
    A3,
    A66,
    TOPREAL1: 7
    
            .=
    R^2-unit_square by 
    TOPREAL1:def 2,
    XBOOLE_1: 4;
    
            
    
            
    
    A161: p2 
    in ( 
    LSeg (p01,p2)) by 
    RLTOPSP1: 68;
    
            p2
    in ( 
    LSeg (p1,p2)) by 
    RLTOPSP1: 68;
    
            then p2
    in (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p01,p2))) by 
    A161,
    XBOOLE_0:def 4;
    
            then
    {p2}
    c= (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p01,p2))) by 
    ZFMISC_1: 31;
    
            then
    
            
    
    A162: (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p01,p2))) 
    =  
    {p2} by
    A124,
    XBOOLE_0:def 10;
    
            p1
    in ( 
    LSeg (p1,p2)) by 
    RLTOPSP1: 68;
    
            then p1
    in (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p1,p11))) by 
    A157,
    XBOOLE_0:def 4;
    
            then
    {p1}
    c= (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p1,p11))) by 
    ZFMISC_1: 31;
    
            then ((
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p1,p11))) 
    =  
    {p1} by
    A147,
    XBOOLE_0:def 10;
    
            
    
            then
    
            
    
    A163: (P1 
    /\ P2) 
    = ( 
    {p1}
    \/ (( 
    LSeg (p1,p2)) 
    /\ (((L4 
    \/ L3) 
    \/ L1) 
    \/ ( 
    LSeg (p01,p2))))) by 
    XBOOLE_1: 23
    
            .= (
    {p1}
    \/ ((( 
    LSeg (p1,p2)) 
    /\ ((L4 
    \/ L3) 
    \/ L1)) 
    \/  
    {p2})) by
    A162,
    XBOOLE_1: 23
    
            .= (
    {p1}
    \/ (((( 
    LSeg (p1,p2)) 
    /\ (L4 
    \/ L3)) 
    \/ (( 
    LSeg (p1,p2)) 
    /\ L1)) 
    \/  
    {p2})) by
    XBOOLE_1: 23
    
            .= (
    {p1}
    \/ ((((( 
    LSeg (p1,p2)) 
    /\ L4) 
    \/ (( 
    LSeg (p1,p2)) 
    /\ L3)) 
    \/ (( 
    LSeg (p1,p2)) 
    /\ L1)) 
    \/  
    {p2})) by
    XBOOLE_1: 23
    
            .= (
    {p1}
    \/ ((( 
    LSeg (p1,p2)) 
    /\ L4) 
    \/ ((( 
    LSeg (p1,p2)) 
    /\ L1) 
    \/  
    {p2}))) by
    A146,
    XBOOLE_1: 4
    
            .= ((
    {p1}
    \/ (( 
    LSeg (p1,p2)) 
    /\ L4)) 
    \/ ((( 
    LSeg (p1,p2)) 
    /\ L1) 
    \/  
    {p2})) by
    XBOOLE_1: 4;
    
            
    
            
    
    A164: (( 
    LSeg (p1,p2)) 
    /\ L1) 
    c= (L2 
    /\ L1) by 
    A3,
    A66,
    TOPREAL1: 6,
    XBOOLE_1: 26;
    
            
    
    A165: 
    
            now
    
              per cases ;
    
                suppose
    
                
    
    A166: p2 
    = p01; 
    
                p2
    in ( 
    LSeg (p1,p2)) by 
    RLTOPSP1: 68;
    
                then ((
    LSeg (p1,p2)) 
    /\ L1) 
    <>  
    {} by 
    A166,
    Lm22,
    XBOOLE_0:def 4;
    
                then ((
    LSeg (p1,p2)) 
    /\ L1) 
    =  
    {p2} by
    A164,
    A166,
    TOPREAL1: 15,
    ZFMISC_1: 33;
    
                hence (P1
    /\ P2) 
    = (( 
    {p1}
    \/ (( 
    LSeg (p1,p2)) 
    /\ L4)) 
    \/  
    {p2}) by
    A163;
    
              end;
    
                suppose
    
                
    
    A167: p2 
    <> p01; 
    
                now
    
                  assume p01
    in (( 
    LSeg (p1,p2)) 
    /\ L1); 
    
                  then p01
    in ( 
    LSeg (p2,p1)) by 
    XBOOLE_0:def 4;
    
                  then (p2
    `1 ) 
    =  
    0 by 
    A13,
    A69,
    A71,
    A123,
    Lm6,
    TOPREAL1: 3;
    
                  hence contradiction by
    A69,
    A72,
    A167,
    EUCLID: 53;
    
                end;
    
                then
    {p01}
    <> (( 
    LSeg (p1,p2)) 
    /\ L1) by 
    ZFMISC_1: 31;
    
                then ((
    LSeg (p1,p2)) 
    /\ L1) 
    =  
    {} by 
    A164,
    TOPREAL1: 15,
    ZFMISC_1: 33;
    
                hence (P1
    /\ P2) 
    = (( 
    {p1}
    \/ (( 
    LSeg (p1,p2)) 
    /\ L4)) 
    \/  
    {p2}) by
    A163;
    
              end;
    
            end;
    
            
    
            
    
    A168: (( 
    LSeg (p1,p2)) 
    /\ L4) 
    c=  
    {p11} by
    A3,
    A66,
    TOPREAL1: 6,
    TOPREAL1: 18,
    XBOOLE_1: 26;
    
            now
    
              per cases ;
    
                suppose
    
                
    
    A169: p1 
    = p11; 
    
                p1
    in ( 
    LSeg (p1,p2)) by 
    RLTOPSP1: 68;
    
                then ((
    LSeg (p1,p2)) 
    /\ L4) 
    <>  
    {} by 
    A169,
    Lm27,
    XBOOLE_0:def 4;
    
                then ((
    LSeg (p1,p2)) 
    /\ L4) 
    =  
    {p1} by
    A168,
    A169,
    ZFMISC_1: 33;
    
                hence (P1
    /\ P2) 
    =  
    {p1, p2} by
    A165,
    ENUMSET1: 1;
    
              end;
    
                suppose
    
                
    
    A170: p1 
    <> p11; 
    
                now
    
                  assume p11
    in (( 
    LSeg (p1,p2)) 
    /\ L4); 
    
                  then p11
    in ( 
    LSeg (p2,p1)) by 
    XBOOLE_0:def 4;
    
                  then (p11
    `1 ) 
    <= (p1 
    `1 ) by 
    A13,
    A69,
    A123,
    TOPREAL1: 3;
    
                  then (p1
    `1 ) 
    = 1 by 
    A13,
    A14,
    Lm10,
    XXREAL_0: 1;
    
                  hence contradiction by
    A13,
    A16,
    A170,
    EUCLID: 53;
    
                end;
    
                then
    {p11}
    <> (( 
    LSeg (p1,p2)) 
    /\ L4) by 
    ZFMISC_1: 31;
    
                then ((
    LSeg (p1,p2)) 
    /\ L4) 
    =  
    {} by 
    A168,
    ZFMISC_1: 33;
    
                hence (P1
    /\ P2) 
    =  
    {p1, p2} by
    A165,
    ENUMSET1: 1;
    
              end;
    
            end;
    
            hence (P1
    /\ P2) 
    =  
    {p1, p2};
    
          end;
    
        end;
    
        hence thesis;
    
      end;
    
        suppose
    
        
    
    A171: p2 
    in L3; 
    
        p00
    in ( 
    LSeg (p00,p2)) by 
    RLTOPSP1: 68;
    
        then
    
        
    
    A172: (( 
    LSeg (p01,p00)) 
    /\ ( 
    LSeg (p00,p2))) 
    <>  
    {} by 
    Lm20,
    XBOOLE_0:def 4;
    
        (
    LSeg (p00,p2)) 
    c= L3 by 
    A171,
    Lm21,
    TOPREAL1: 6;
    
        then ((
    LSeg (p01,p00)) 
    /\ ( 
    LSeg (p00,p2))) 
    c=  
    {p00} by
    TOPREAL1: 17,
    XBOOLE_1: 27;
    
        then ((
    LSeg (p01,p00)) 
    /\ ( 
    LSeg (p00,p2))) 
    =  
    {p00} by
    A172,
    ZFMISC_1: 33;
    
        then
    
        
    
    A173: (L1 
    \/ ( 
    LSeg (p00,p2))) 
    is_an_arc_of (p01,p2) by 
    Lm5,
    Lm7,
    TOPREAL1: 12;
    
        (
    LSeg (p2,p00)) 
    c= L3 by 
    A171,
    Lm21,
    TOPREAL1: 6;
    
        then
    
        
    
    A174: (( 
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p00,p2))) 
    =  
    {} by 
    A11,
    Lm2,
    XBOOLE_1: 3,
    XBOOLE_1: 27;
    
        p10
    in ( 
    LSeg (p10,p2)) by 
    RLTOPSP1: 68;
    
        then
    
        
    
    A175: p10 
    in (( 
    LSeg (p11,p10)) 
    /\ ( 
    LSeg (p10,p2))) by 
    Lm25,
    XBOOLE_0:def 4;
    
        (
    LSeg (p10,p2)) 
    c= L3 by 
    A171,
    Lm24,
    TOPREAL1: 6;
    
        then ((
    LSeg (p11,p10)) 
    /\ ( 
    LSeg (p10,p2))) 
    c= (L4 
    /\ L3) by 
    XBOOLE_1: 27;
    
        then ((
    LSeg (p11,p10)) 
    /\ ( 
    LSeg (p10,p2))) 
    =  
    {p10} by
    A175,
    TOPREAL1: 16,
    ZFMISC_1: 33;
    
        then
    
        
    
    A176: (L4 
    \/ ( 
    LSeg (p10,p2))) 
    is_an_arc_of (p11,p2) by 
    Lm9,
    Lm11,
    TOPREAL1: 12;
    
        take P1 = (((
    LSeg (p1,p11)) 
    \/ L4) 
    \/ ( 
    LSeg (p10,p2))), P2 = ((( 
    LSeg (p1,p01)) 
    \/ L1) 
    \/ ( 
    LSeg (p00,p2))); 
    
        
    
        
    
    A177: (( 
    LSeg (p1,p11)) 
    \/ ( 
    LSeg (p1,p01))) 
    = L2 by 
    A3,
    TOPREAL1: 5;
    
        
    
        
    
    A178: ( 
    LSeg (p2,p10)) 
    c= L3 by 
    A171,
    Lm24,
    TOPREAL1: 6;
    
        then
    
        
    
    A179: (( 
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p10,p2))) 
    =  
    {} by 
    A8,
    Lm2,
    XBOOLE_1: 3,
    XBOOLE_1: 27;
    
        
    
        
    
    A180: (L2 
    /\ ( 
    LSeg (p00,p2))) 
    c= (L2 
    /\ L3) by 
    A171,
    Lm21,
    TOPREAL1: 6,
    XBOOLE_1: 26;
    
        ((
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p00,p2))) 
    c= (L2 
    /\ ( 
    LSeg (p00,p2))) by 
    A3,
    Lm26,
    TOPREAL1: 6,
    XBOOLE_1: 26;
    
        then
    
        
    
    A181: (( 
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p00,p2))) 
    =  
    {} by 
    A180,
    Lm2,
    XBOOLE_1: 1,
    XBOOLE_1: 3;
    
        
    
        
    
    A182: (( 
    LSeg (p10,p2)) 
    /\ ( 
    LSeg (p1,p01))) 
    =  
    {} by 
    A11,
    A178,
    Lm2,
    XBOOLE_1: 3,
    XBOOLE_1: 27;
    
        
    
        
    
    A183: (( 
    LSeg (p10,p2)) 
    /\ ( 
    LSeg (p00,p2))) 
    =  
    {p2} by
    A171,
    TOPREAL1: 8;
    
        ((
    LSeg (p1,p11)) 
    /\ (L4 
    \/ ( 
    LSeg (p10,p2)))) 
    = ((( 
    LSeg (p1,p11)) 
    /\ L4) 
    \/ (( 
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p10,p2)))) by 
    XBOOLE_1: 23
    
        .=
    {p11} by
    A6,
    A10,
    A179,
    ZFMISC_1: 33;
    
        then ((
    LSeg (p1,p11)) 
    \/ (L4 
    \/ ( 
    LSeg (p10,p2)))) 
    is_an_arc_of (p1,p2) by 
    A176,
    TOPREAL1: 11;
    
        hence P1
    is_an_arc_of (p1,p2) by 
    XBOOLE_1: 4;
    
        
    
        
    
    A184: ex q2 st q2 
    = p2 & (q2 
    `1 ) 
    <= 1 & (q2 
    `1 ) 
    >=  
    0 & (q2 
    `2 ) 
    =  
    0 by 
    A171,
    TOPREAL1: 13;
    
        ((
    LSeg (p1,p01)) 
    /\ (L1 
    \/ ( 
    LSeg (p00,p2)))) 
    = ((( 
    LSeg (p01,p1)) 
    /\ L1) 
    \/ (( 
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p00,p2)))) by 
    XBOOLE_1: 23
    
        .=
    {p01} by
    A7,
    A5,
    A174,
    TOPREAL1: 15,
    ZFMISC_1: 33;
    
        then ((
    LSeg (p1,p01)) 
    \/ (L1 
    \/ ( 
    LSeg (p00,p2)))) 
    is_an_arc_of (p1,p2) by 
    A173,
    TOPREAL1: 11;
    
        hence P2
    is_an_arc_of (p1,p2) by 
    XBOOLE_1: 4;
    
        ((
    LSeg (p10,p2)) 
    \/ ( 
    LSeg (p00,p2))) 
    = L3 by 
    A171,
    TOPREAL1: 5;
    
        
    
        hence
    R^2-unit_square  
    = (L2 
    \/ ((L4 
    \/ (( 
    LSeg (p10,p2)) 
    \/ ( 
    LSeg (p00,p2)))) 
    \/ L1)) by 
    TOPREAL1:def 2,
    XBOOLE_1: 4
    
        .= (L2
    \/ (((L4 
    \/ ( 
    LSeg (p10,p2))) 
    \/ ( 
    LSeg (p00,p2))) 
    \/ L1)) by 
    XBOOLE_1: 4
    
        .= (L2
    \/ ((L4 
    \/ ( 
    LSeg (p10,p2))) 
    \/ (L1 
    \/ ( 
    LSeg (p00,p2))))) by 
    XBOOLE_1: 4
    
        .= ((
    LSeg (p1,p11)) 
    \/ (((L4 
    \/ ( 
    LSeg (p10,p2))) 
    \/ (L1 
    \/ ( 
    LSeg (p00,p2)))) 
    \/ ( 
    LSeg (p1,p01)))) by 
    A177,
    XBOOLE_1: 4
    
        .= ((
    LSeg (p1,p11)) 
    \/ ((L4 
    \/ ( 
    LSeg (p10,p2))) 
    \/ ((L1 
    \/ ( 
    LSeg (p00,p2))) 
    \/ ( 
    LSeg (p1,p01))))) by 
    XBOOLE_1: 4
    
        .= (((
    LSeg (p1,p11)) 
    \/ (L4 
    \/ ( 
    LSeg (p10,p2)))) 
    \/ ((L1 
    \/ ( 
    LSeg (p00,p2))) 
    \/ ( 
    LSeg (p1,p01)))) by 
    XBOOLE_1: 4
    
        .= ((((
    LSeg (p1,p11)) 
    \/ L4) 
    \/ ( 
    LSeg (p10,p2))) 
    \/ (( 
    LSeg (p1,p01)) 
    \/ (L1 
    \/ ( 
    LSeg (p00,p2))))) by 
    XBOOLE_1: 4
    
        .= (P1
    \/ P2) by 
    XBOOLE_1: 4;
    
        
    
        
    
    A185: (( 
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p1,p01))) 
    =  
    {p1} by
    A3,
    TOPREAL1: 8;
    
        
    
        
    
    A186: (P1 
    /\ P2) 
    = (((( 
    LSeg (p1,p11)) 
    \/ L4) 
    /\ ((( 
    LSeg (p1,p01)) 
    \/ L1) 
    \/ ( 
    LSeg (p00,p2)))) 
    \/ (( 
    LSeg (p10,p2)) 
    /\ ((( 
    LSeg (p1,p01)) 
    \/ L1) 
    \/ ( 
    LSeg (p00,p2))))) by 
    XBOOLE_1: 23
    
        .= ((((
    LSeg (p1,p11)) 
    /\ ((( 
    LSeg (p1,p01)) 
    \/ L1) 
    \/ ( 
    LSeg (p00,p2)))) 
    \/ (L4 
    /\ ((( 
    LSeg (p1,p01)) 
    \/ L1) 
    \/ ( 
    LSeg (p00,p2))))) 
    \/ (( 
    LSeg (p10,p2)) 
    /\ ((( 
    LSeg (p1,p01)) 
    \/ L1) 
    \/ ( 
    LSeg (p00,p2))))) by 
    XBOOLE_1: 23
    
        .= (((((
    LSeg (p1,p11)) 
    /\ (( 
    LSeg (p1,p01)) 
    \/ L1)) 
    \/ (( 
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p00,p2)))) 
    \/ (L4 
    /\ ((( 
    LSeg (p1,p01)) 
    \/ L1) 
    \/ ( 
    LSeg (p00,p2))))) 
    \/ (( 
    LSeg (p10,p2)) 
    /\ ((( 
    LSeg (p1,p01)) 
    \/ L1) 
    \/ ( 
    LSeg (p00,p2))))) by 
    XBOOLE_1: 23
    
        .= (((((
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p1,p01))) 
    \/ (( 
    LSeg (p1,p11)) 
    /\ L1)) 
    \/ (L4 
    /\ ((( 
    LSeg (p1,p01)) 
    \/ L1) 
    \/ ( 
    LSeg (p00,p2))))) 
    \/ (( 
    LSeg (p10,p2)) 
    /\ ((( 
    LSeg (p1,p01)) 
    \/ L1) 
    \/ ( 
    LSeg (p00,p2))))) by 
    A181,
    XBOOLE_1: 23
    
        .= (((
    {p1}
    \/ (( 
    LSeg (p1,p11)) 
    /\ L1)) 
    \/ ((L4 
    /\ (( 
    LSeg (p1,p01)) 
    \/ L1)) 
    \/ (L4 
    /\ ( 
    LSeg (p00,p2))))) 
    \/ (( 
    LSeg (p10,p2)) 
    /\ ((( 
    LSeg (p1,p01)) 
    \/ L1) 
    \/ ( 
    LSeg (p00,p2))))) by 
    A185,
    XBOOLE_1: 23
    
        .= (((
    {p1}
    \/ (( 
    LSeg (p1,p11)) 
    /\ L1)) 
    \/ (((L4 
    /\ ( 
    LSeg (p1,p01))) 
    \/ (L1 
    /\ L4)) 
    \/ (L4 
    /\ ( 
    LSeg (p00,p2))))) 
    \/ (( 
    LSeg (p10,p2)) 
    /\ ((( 
    LSeg (p1,p01)) 
    \/ L1) 
    \/ ( 
    LSeg (p00,p2))))) by 
    XBOOLE_1: 23
    
        .= (((
    {p1}
    \/ (( 
    LSeg (p1,p11)) 
    /\ L1)) 
    \/ ((L4 
    /\ ( 
    LSeg (p1,p01))) 
    \/ (L4 
    /\ ( 
    LSeg (p00,p2))))) 
    \/ ((( 
    LSeg (p10,p2)) 
    /\ (( 
    LSeg (p1,p01)) 
    \/ L1)) 
    \/  
    {p2})) by
    A183,
    Lm3,
    XBOOLE_1: 23
    
        .= (((
    {p1}
    \/ (( 
    LSeg (p1,p11)) 
    /\ L1)) 
    \/ ((L4 
    /\ ( 
    LSeg (p1,p01))) 
    \/ (L4 
    /\ ( 
    LSeg (p00,p2))))) 
    \/ (((( 
    LSeg (p10,p2)) 
    /\ ( 
    LSeg (p1,p01))) 
    \/ (( 
    LSeg (p10,p2)) 
    /\ L1)) 
    \/  
    {p2})) by
    XBOOLE_1: 23
    
        .= (((
    {p1}
    \/ (( 
    LSeg (p1,p11)) 
    /\ L1)) 
    \/ ((L4 
    /\ ( 
    LSeg (p1,p01))) 
    \/ (L4 
    /\ ( 
    LSeg (p00,p2))))) 
    \/ ((( 
    LSeg (p10,p2)) 
    /\ L1) 
    \/  
    {p2})) by
    A182;
    
        
    
    A187: 
    
        now
    
          per cases ;
    
            suppose
    
            
    
    A188: p1 
    = p01; 
    
            
    
            then (L4
    /\ ( 
    LSeg (p1,p01))) 
    = (L4 
    /\  
    {p01}) by
    RLTOPSP1: 70
    
            .=
    {} by 
    Lm1,
    Lm15;
    
            hence (P1
    /\ P2) 
    = (( 
    {p1}
    \/ (L4 
    /\ ( 
    LSeg (p00,p2)))) 
    \/ ((( 
    LSeg (p10,p2)) 
    /\ L1) 
    \/  
    {p2})) by
    A186,
    A188,
    TOPREAL1: 15;
    
          end;
    
            suppose
    
            
    
    A189: p1 
    = p11; 
    
            
    
            then ((
    LSeg (p1,p11)) 
    /\ L1) 
    = ( 
    {p11}
    /\ L1) by 
    RLTOPSP1: 70
    
            .=
    {} by 
    Lm1,
    Lm18;
    
            
    
            hence (P1
    /\ P2) 
    = ((( 
    {p1}
    \/  
    {p1})
    \/ (L4 
    /\ ( 
    LSeg (p00,p2)))) 
    \/ ((( 
    LSeg (p10,p2)) 
    /\ L1) 
    \/  
    {p2})) by
    A186,
    A189,
    TOPREAL1: 18,
    XBOOLE_1: 4
    
            .= ((
    {p1}
    \/ (L4 
    /\ ( 
    LSeg (p00,p2)))) 
    \/ ((( 
    LSeg (p10,p2)) 
    /\ L1) 
    \/  
    {p2}));
    
          end;
    
            suppose
    
            
    
    A190: p1 
    <> p11 & p1 
    <> p01; 
    
            now
    
              assume p11
    in (L4 
    /\ ( 
    LSeg (p1,p01))); 
    
              then
    
              
    
    A191: p11 
    in ( 
    LSeg (p01,p1)) by 
    XBOOLE_0:def 4;
    
              (p01
    `1 ) 
    <= (p1 
    `1 ) by 
    A13,
    A15,
    EUCLID: 52;
    
              then 1
    <= (p1 
    `1 ) by 
    A191,
    Lm10,
    TOPREAL1: 3;
    
              then (p1
    `1 ) 
    = 1 by 
    A13,
    A14,
    XXREAL_0: 1;
    
              hence contradiction by
    A13,
    A16,
    A190,
    EUCLID: 53;
    
            end;
    
            then
    
            
    
    A192: 
    {p11}
    <> (L4 
    /\ ( 
    LSeg (p1,p01))) by 
    ZFMISC_1: 31;
    
            (L4
    /\ ( 
    LSeg (p1,p01))) 
    c= (L4 
    /\ L2) by 
    A3,
    Lm23,
    TOPREAL1: 6,
    XBOOLE_1: 26;
    
            then
    
            
    
    A193: (L4 
    /\ ( 
    LSeg (p1,p01))) 
    =  
    {} by 
    A192,
    TOPREAL1: 18,
    ZFMISC_1: 33;
    
            now
    
              assume p01
    in (( 
    LSeg (p1,p11)) 
    /\ L1); 
    
              then
    
              
    
    A194: p01 
    in ( 
    LSeg (p1,p11)) by 
    XBOOLE_0:def 4;
    
              (p1
    `1 ) 
    <= (p11 
    `1 ) by 
    A13,
    A14,
    EUCLID: 52;
    
              then (p1
    `1 ) 
    =  
    0 by 
    A13,
    A15,
    A194,
    Lm6,
    TOPREAL1: 3;
    
              hence contradiction by
    A13,
    A16,
    A190,
    EUCLID: 53;
    
            end;
    
            then
    
            
    
    A195: 
    {p01}
    <> (( 
    LSeg (p1,p11)) 
    /\ L1) by 
    ZFMISC_1: 31;
    
            ((
    LSeg (p1,p11)) 
    /\ L1) 
    c= (L2 
    /\ L1) by 
    A3,
    Lm26,
    TOPREAL1: 6,
    XBOOLE_1: 26;
    
            then ((
    LSeg (p1,p11)) 
    /\ L1) 
    =  
    {} by 
    A195,
    TOPREAL1: 15,
    ZFMISC_1: 33;
    
            hence (P1
    /\ P2) 
    = (( 
    {p1}
    \/ (L4 
    /\ ( 
    LSeg (p00,p2)))) 
    \/ ((( 
    LSeg (p10,p2)) 
    /\ L1) 
    \/  
    {p2})) by
    A186,
    A193;
    
          end;
    
        end;
    
        now
    
          per cases ;
    
            suppose
    
            
    
    A196: p2 
    = p00; 
    
            
    
            then (L4
    /\ ( 
    LSeg (p00,p2))) 
    = (L4 
    /\  
    {p00}) by
    RLTOPSP1: 70
    
            .=
    {} by 
    Lm1,
    Lm12;
    
            hence thesis by
    A187,
    A196,
    ENUMSET1: 1,
    TOPREAL1: 17;
    
          end;
    
            suppose
    
            
    
    A197: p2 
    = p10; 
    
            
    
            then ((
    LSeg (p10,p2)) 
    /\ L1) 
    = ( 
    {p10}
    /\ L1) by 
    RLTOPSP1: 70
    
            .=
    {} by 
    Lm1,
    Lm16;
    
            
    
            hence (P1
    /\ P2) 
    = ( 
    {p1}
    \/ ( 
    {p2}
    \/  
    {p2})) by
    A187,
    A197,
    TOPREAL1: 16,
    XBOOLE_1: 4
    
            .=
    {p1, p2} by
    ENUMSET1: 1;
    
          end;
    
            suppose
    
            
    
    A198: p2 
    <> p10 & p2 
    <> p00; 
    
            now
    
              assume p00
    in (( 
    LSeg (p10,p2)) 
    /\ L1); 
    
              then
    
              
    
    A199: p00 
    in ( 
    LSeg (p2,p10)) by 
    XBOOLE_0:def 4;
    
              (p2
    `1 ) 
    <= (p10 
    `1 ) by 
    A184,
    EUCLID: 52;
    
              then (p2
    `1 ) 
    =  
    0 by 
    A184,
    A199,
    Lm4,
    TOPREAL1: 3;
    
              hence contradiction by
    A184,
    A198,
    EUCLID: 53;
    
            end;
    
            then
    
            
    
    A200: 
    {p00}
    <> (( 
    LSeg (p10,p2)) 
    /\ L1) by 
    ZFMISC_1: 31;
    
            ((
    LSeg (p10,p2)) 
    /\ L1) 
    c= (L3 
    /\ L1) by 
    A171,
    Lm24,
    TOPREAL1: 6,
    XBOOLE_1: 26;
    
            then
    
            
    
    A201: (( 
    LSeg (p10,p2)) 
    /\ L1) 
    =  
    {} by 
    A200,
    TOPREAL1: 17,
    ZFMISC_1: 33;
    
            now
    
              assume p10
    in (L4 
    /\ ( 
    LSeg (p00,p2))); 
    
              then
    
              
    
    A202: p10 
    in ( 
    LSeg (p00,p2)) by 
    XBOOLE_0:def 4;
    
              (p00
    `1 ) 
    <= (p2 
    `1 ) by 
    A184,
    EUCLID: 52;
    
              then 1
    <= (p2 
    `1 ) by 
    A202,
    Lm8,
    TOPREAL1: 3;
    
              then (p2
    `1 ) 
    = 1 by 
    A184,
    XXREAL_0: 1;
    
              hence contradiction by
    A184,
    A198,
    EUCLID: 53;
    
            end;
    
            then
    
            
    
    A203: 
    {p10}
    <> (L4 
    /\ ( 
    LSeg (p00,p2))) by 
    ZFMISC_1: 31;
    
            (L4
    /\ ( 
    LSeg (p00,p2))) 
    c= (L4 
    /\ L3) by 
    A171,
    Lm21,
    TOPREAL1: 6,
    XBOOLE_1: 26;
    
            then (L4
    /\ ( 
    LSeg (p00,p2))) 
    =  
    {} by 
    A203,
    TOPREAL1: 16,
    ZFMISC_1: 33;
    
            hence thesis by
    A187,
    A201,
    ENUMSET1: 1;
    
          end;
    
        end;
    
        hence thesis;
    
      end;
    
        suppose
    
        
    
    A204: p2 
    in L4; 
    
        then
    
        
    
    A205: ( 
    LSeg (p11,p2)) 
    c= L4 by 
    Lm27,
    TOPREAL1: 6;
    
        (
    LSeg (p1,p11)) 
    c= L2 by 
    A3,
    Lm26,
    TOPREAL1: 6;
    
        then
    
        
    
    A206: (( 
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p11,p2))) 
    c= (L2 
    /\ L4) by 
    A205,
    XBOOLE_1: 27;
    
        take P1 = ((
    LSeg (p1,p11)) 
    \/ ( 
    LSeg (p11,p2))), P2 = (( 
    LSeg (p1,p01)) 
    \/ ((L1 
    \/ L3) 
    \/ ( 
    LSeg (p10,p2)))); 
    
        
    
        
    
    A207: p11 
    in ( 
    LSeg (p11,p2)) by 
    RLTOPSP1: 68;
    
        p10
    in ( 
    LSeg (p10,p2)) by 
    RLTOPSP1: 68;
    
        then
    
        
    
    A208: (L3 
    /\ ( 
    LSeg (p10,p2))) 
    <>  
    {} by 
    Lm24,
    XBOOLE_0:def 4;
    
        p11
    in ( 
    LSeg (p1,p11)) by 
    RLTOPSP1: 68;
    
        then ((
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p11,p2))) 
    <>  
    {} by 
    A207,
    XBOOLE_0:def 4;
    
        then
    
        
    
    A209: (( 
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p11,p2))) 
    =  
    {p11} by
    A206,
    TOPREAL1: 18,
    ZFMISC_1: 33;
    
        p1
    <> p11 or p11 
    <> p2 by 
    A1;
    
        hence P1
    is_an_arc_of (p1,p2) by 
    A209,
    TOPREAL1: 12;
    
        
    
        
    
    A210: L2 
    = (( 
    LSeg (p1,p11)) 
    \/ ( 
    LSeg (p1,p01))) by 
    A3,
    TOPREAL1: 5;
    
        
    
        
    
    A211: L3 
    is_an_arc_of (p00,p10) by 
    Lm4,
    Lm8,
    TOPREAL1: 9;
    
        L1
    is_an_arc_of (p01,p00) by 
    Lm5,
    Lm7,
    TOPREAL1: 9;
    
        then
    
        
    
    A212: (L1 
    \/ L3) 
    is_an_arc_of (p01,p10) by 
    A211,
    TOPREAL1: 2,
    TOPREAL1: 17;
    
        
    
        
    
    A213: (( 
    LSeg (p11,p2)) 
    /\ ( 
    LSeg (p10,p2))) 
    =  
    {p2} by
    A204,
    TOPREAL1: 8;
    
        
    
        
    
    A214: L4 
    = (( 
    LSeg (p10,p2)) 
    \/ ( 
    LSeg (p11,p2))) by 
    A204,
    TOPREAL1: 5;
    
        
    
        
    
    A215: ( 
    LSeg (p10,p2)) 
    c= L4 by 
    A204,
    Lm25,
    TOPREAL1: 6;
    
        then
    
        
    
    A216: (L3 
    /\ ( 
    LSeg (p10,p2))) 
    c=  
    {p10} by
    TOPREAL1: 16,
    XBOOLE_1: 27;
    
        
    
        
    
    A217: ex q st q 
    = p2 & (q 
    `1 ) 
    = 1 & (q 
    `2 ) 
    <= 1 & (q 
    `2 ) 
    >=  
    0 by 
    A204,
    TOPREAL1: 13;
    
        now
    
          
    
          
    
    A218: (p10 
    `2 ) 
    <= (p2 
    `2 ) by 
    A217,
    EUCLID: 52;
    
          assume
    
          
    
    A219: p11 
    in (( 
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p10,p2))); 
    
          then
    
          
    
    A220: p11 
    in ( 
    LSeg (p01,p1)) by 
    XBOOLE_0:def 4;
    
          p11
    in ( 
    LSeg (p10,p2)) by 
    A219,
    XBOOLE_0:def 4;
    
          then (p11
    `2 ) 
    <= (p2 
    `2 ) by 
    A218,
    TOPREAL1: 4;
    
          then
    
          
    
    A221: (p11 
    `2 ) 
    = (p2 
    `2 ) by 
    A217,
    Lm11,
    XXREAL_0: 1;
    
          (p01
    `1 ) 
    <= (p1 
    `1 ) by 
    A13,
    A15,
    EUCLID: 52;
    
          then (p11
    `1 ) 
    <= (p1 
    `1 ) by 
    A220,
    TOPREAL1: 3;
    
          then (p11
    `1 ) 
    = (p1 
    `1 ) by 
    A13,
    A14,
    Lm10,
    XXREAL_0: 1;
    
          
    
          then p1
    =  
    |[(p11
    `1 ), (p11 
    `2 )]| by 
    A13,
    A16,
    Lm11,
    EUCLID: 53
    
          .= p2 by
    A217,
    A221,
    Lm10,
    EUCLID: 53;
    
          hence contradiction by
    A1;
    
        end;
    
        then
    
        
    
    A222: 
    {p11}
    <> (( 
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p10,p2))) by 
    ZFMISC_1: 31;
    
        
    
        
    
    A223: (L1 
    /\ ( 
    LSeg (p10,p2))) 
    =  
    {} by 
    A215,
    Lm3,
    XBOOLE_1: 3,
    XBOOLE_1: 26;
    
        ((L1
    \/ L3) 
    /\ ( 
    LSeg (p10,p2))) 
    = ((L1 
    /\ ( 
    LSeg (p10,p2))) 
    \/ (L3 
    /\ ( 
    LSeg (p10,p2)))) by 
    XBOOLE_1: 23
    
        .=
    {p10} by
    A223,
    A216,
    A208,
    ZFMISC_1: 33;
    
        then
    
        
    
    A224: ((L1 
    \/ L3) 
    \/ ( 
    LSeg (p10,p2))) 
    is_an_arc_of (p01,p2) by 
    A212,
    TOPREAL1: 10;
    
        
    
        
    
    A225: ( 
    LSeg (p2,p11)) 
    c= L4 by 
    A204,
    Lm27,
    TOPREAL1: 6;
    
        then
    
        
    
    A226: (( 
    LSeg (p11,p2)) 
    /\ L1) 
    =  
    {} by 
    Lm3,
    XBOOLE_1: 3,
    XBOOLE_1: 27;
    
        ((
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p10,p2))) 
    c=  
    {p11} by
    A11,
    A215,
    TOPREAL1: 18,
    XBOOLE_1: 27;
    
        then
    
        
    
    A227: (( 
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p10,p2))) 
    =  
    {} by 
    A222,
    ZFMISC_1: 33;
    
        ((
    LSeg (p1,p01)) 
    /\ ((L1 
    \/ L3) 
    \/ ( 
    LSeg (p10,p2)))) 
    = ((( 
    LSeg (p1,p01)) 
    /\ (L1 
    \/ L3)) 
    \/ (( 
    LSeg (p1,p01)) 
    /\ ( 
    LSeg (p10,p2)))) by 
    XBOOLE_1: 23
    
        .= (((
    LSeg (p1,p01)) 
    /\ L1) 
    \/ (( 
    LSeg (p1,p01)) 
    /\ L3)) by 
    A227,
    XBOOLE_1: 23
    
        .=
    {p01} by
    A12,
    A7,
    A5,
    TOPREAL1: 15,
    ZFMISC_1: 33;
    
        hence P2
    is_an_arc_of (p1,p2) by 
    A224,
    TOPREAL1: 11;
    
        
    
        thus (P1
    \/ P2) 
    = (( 
    LSeg (p11,p2)) 
    \/ (( 
    LSeg (p1,p11)) 
    \/ (( 
    LSeg (p1,p01)) 
    \/ ((L1 
    \/ L3) 
    \/ ( 
    LSeg (p10,p2)))))) by 
    XBOOLE_1: 4
    
        .= ((L2
    \/ ((L1 
    \/ L3) 
    \/ ( 
    LSeg (p10,p2)))) 
    \/ ( 
    LSeg (p11,p2))) by 
    A210,
    XBOOLE_1: 4
    
        .= (L2
    \/ (((L1 
    \/ L3) 
    \/ ( 
    LSeg (p10,p2))) 
    \/ ( 
    LSeg (p11,p2)))) by 
    XBOOLE_1: 4
    
        .= (L2
    \/ ((L1 
    \/ L3) 
    \/ (( 
    LSeg (p10,p2)) 
    \/ ( 
    LSeg (p11,p2))))) by 
    XBOOLE_1: 4
    
        .= (L2
    \/ (L1 
    \/ (L3 
    \/ L4))) by 
    A214,
    XBOOLE_1: 4
    
        .=
    R^2-unit_square by 
    TOPREAL1:def 2,
    XBOOLE_1: 4;
    
        
    
        
    
    A228: 
    {p1}
    = (( 
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p1,p01))) by 
    A3,
    TOPREAL1: 8;
    
        
    
        
    
    A229: (P1 
    /\ P2) 
    = ((( 
    LSeg (p1,p11)) 
    /\ (( 
    LSeg (p1,p01)) 
    \/ ((L1 
    \/ L3) 
    \/ ( 
    LSeg (p10,p2))))) 
    \/ (( 
    LSeg (p11,p2)) 
    /\ (( 
    LSeg (p1,p01)) 
    \/ ((L1 
    \/ L3) 
    \/ ( 
    LSeg (p10,p2)))))) by 
    XBOOLE_1: 23
    
        .= ((((
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p1,p01))) 
    \/ (( 
    LSeg (p1,p11)) 
    /\ ((L1 
    \/ L3) 
    \/ ( 
    LSeg (p10,p2))))) 
    \/ (( 
    LSeg (p11,p2)) 
    /\ (( 
    LSeg (p1,p01)) 
    \/ ((L1 
    \/ L3) 
    \/ ( 
    LSeg (p10,p2)))))) by 
    XBOOLE_1: 23
    
        .= ((
    {p1}
    \/ ((( 
    LSeg (p1,p11)) 
    /\ (L1 
    \/ L3)) 
    \/ (( 
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p10,p2))))) 
    \/ (( 
    LSeg (p11,p2)) 
    /\ (( 
    LSeg (p1,p01)) 
    \/ ((L1 
    \/ L3) 
    \/ ( 
    LSeg (p10,p2)))))) by 
    A228,
    XBOOLE_1: 23
    
        .= ((
    {p1}
    \/ (((( 
    LSeg (p1,p11)) 
    /\ L1) 
    \/ (( 
    LSeg (p1,p11)) 
    /\ L3)) 
    \/ (( 
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p10,p2))))) 
    \/ (( 
    LSeg (p11,p2)) 
    /\ (( 
    LSeg (p1,p01)) 
    \/ ((L1 
    \/ L3) 
    \/ ( 
    LSeg (p10,p2)))))) by 
    XBOOLE_1: 23
    
        .= ((
    {p1}
    \/ (((( 
    LSeg (p1,p11)) 
    /\ L1) 
    \/ (( 
    LSeg (p1,p11)) 
    /\ L3)) 
    \/ (( 
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p10,p2))))) 
    \/ ((( 
    LSeg (p11,p2)) 
    /\ ( 
    LSeg (p1,p01))) 
    \/ (( 
    LSeg (p11,p2)) 
    /\ ((L1 
    \/ L3) 
    \/ ( 
    LSeg (p10,p2)))))) by 
    XBOOLE_1: 23
    
        .= ((
    {p1}
    \/ (((( 
    LSeg (p1,p11)) 
    /\ L1) 
    \/ (( 
    LSeg (p1,p11)) 
    /\ L3)) 
    \/ (( 
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p10,p2))))) 
    \/ ((( 
    LSeg (p11,p2)) 
    /\ ( 
    LSeg (p1,p01))) 
    \/ ((( 
    LSeg (p11,p2)) 
    /\ (L1 
    \/ L3)) 
    \/  
    {p2}))) by
    A213,
    XBOOLE_1: 23
    
        .= ((
    {p1}
    \/ (((( 
    LSeg (p1,p11)) 
    /\ L1) 
    \/ (( 
    LSeg (p1,p11)) 
    /\ L3)) 
    \/ (( 
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p10,p2))))) 
    \/ ((( 
    LSeg (p11,p2)) 
    /\ ( 
    LSeg (p1,p01))) 
    \/ (((( 
    LSeg (p11,p2)) 
    /\ L1) 
    \/ (( 
    LSeg (p11,p2)) 
    /\ L3)) 
    \/  
    {p2}))) by
    XBOOLE_1: 23
    
        .= ((
    {p1}
    \/ ((( 
    LSeg (p1,p11)) 
    /\ L1) 
    \/ (( 
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p10,p2))))) 
    \/ ((( 
    LSeg (p11,p2)) 
    /\ ( 
    LSeg (p1,p01))) 
    \/ ((( 
    LSeg (p11,p2)) 
    /\ L3) 
    \/  
    {p2}))) by
    A9,
    A226;
    
        
    
    A230: 
    
        now
    
          per cases ;
    
            suppose
    
            
    
    A231: p2 
    = p10; 
    
            then
    
            
    
    A232: not p2 
    in ( 
    LSeg (p1,p11)) by 
    A8,
    Lm7,
    Lm9,
    Lm11,
    TOPREAL1: 4;
    
            ((
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p10,p2))) 
    = (( 
    LSeg (p1,p11)) 
    /\  
    {p2}) by
    A231,
    RLTOPSP1: 70
    
            .=
    {} by 
    A232,
    Lm1;
    
            hence (P1
    /\ P2) 
    = (( 
    {p1}
    \/ (( 
    LSeg (p1,p11)) 
    /\ L1)) 
    \/ ((( 
    LSeg (p11,p2)) 
    /\ ( 
    LSeg (p1,p01))) 
    \/  
    {p2})) by
    A229,
    A231,
    TOPREAL1: 16;
    
          end;
    
            suppose
    
            
    
    A233: p2 
    = p11; 
    
            then p2
    in ( 
    LSeg (p1,p11)) by 
    RLTOPSP1: 68;
    
            then
    
            
    
    A234: (( 
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p10,p2))) 
    <>  
    {} by 
    A233,
    Lm27,
    XBOOLE_0:def 4;
    
            ((
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p10,p2))) 
    c=  
    {p2} by
    A8,
    A233,
    TOPREAL1: 18,
    XBOOLE_1: 27;
    
            then
    
            
    
    A235: (( 
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p10,p2))) 
    =  
    {p2} by
    A234,
    ZFMISC_1: 33;
    
            ((
    LSeg (p11,p2)) 
    /\ L3) 
    = ( 
    {p11}
    /\ L3) by 
    A233,
    RLTOPSP1: 70
    
            .=
    {} by 
    Lm1,
    Lm19;
    
            
    
            hence (P1
    /\ P2) 
    = ((( 
    {p1}
    \/ (( 
    LSeg (p1,p11)) 
    /\ L1)) 
    \/  
    {p2})
    \/ ((( 
    LSeg (p11,p2)) 
    /\ ( 
    LSeg (p1,p01))) 
    \/  
    {p2})) by
    A229,
    A235,
    XBOOLE_1: 4
    
            .= ((
    {p1}
    \/ (( 
    LSeg (p1,p11)) 
    /\ L1)) 
    \/ (((( 
    LSeg (p11,p2)) 
    /\ ( 
    LSeg (p1,p01))) 
    \/  
    {p2})
    \/  
    {p2})) by
    XBOOLE_1: 4
    
            .= ((
    {p1}
    \/ (( 
    LSeg (p1,p11)) 
    /\ L1)) 
    \/ ((( 
    LSeg (p11,p2)) 
    /\ ( 
    LSeg (p1,p01))) 
    \/ ( 
    {p2}
    \/  
    {p2}))) by
    XBOOLE_1: 4
    
            .= ((
    {p1}
    \/ (( 
    LSeg (p1,p11)) 
    /\ L1)) 
    \/ ((( 
    LSeg (p11,p2)) 
    /\ ( 
    LSeg (p1,p01))) 
    \/  
    {p2}));
    
          end;
    
            suppose
    
            
    
    A236: p2 
    <> p11 & p2 
    <> p10; 
    
            now
    
              assume p11
    in (( 
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p10,p2))); 
    
              then
    
              
    
    A237: p11 
    in ( 
    LSeg (p10,p2)) by 
    XBOOLE_0:def 4;
    
              (p10
    `2 ) 
    <= (p2 
    `2 ) by 
    A217,
    EUCLID: 52;
    
              then (p11
    `2 ) 
    <= (p2 
    `2 ) by 
    A237,
    TOPREAL1: 4;
    
              then (p2
    `2 ) 
    = 1 by 
    A217,
    Lm11,
    XXREAL_0: 1;
    
              hence contradiction by
    A217,
    A236,
    EUCLID: 53;
    
            end;
    
            then
    
            
    
    A238: 
    {p11}
    <> (( 
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p10,p2))) by 
    ZFMISC_1: 31;
    
            ((
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p10,p2))) 
    c=  
    {p11} by
    A8,
    A215,
    TOPREAL1: 18,
    XBOOLE_1: 27;
    
            then
    
            
    
    A239: (( 
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p10,p2))) 
    =  
    {} by 
    A238,
    ZFMISC_1: 33;
    
            now
    
              assume p10
    in (( 
    LSeg (p11,p2)) 
    /\ L3); 
    
              then
    
              
    
    A240: p10 
    in ( 
    LSeg (p2,p11)) by 
    XBOOLE_0:def 4;
    
              (p2
    `2 ) 
    <= (p11 
    `2 ) by 
    A217,
    EUCLID: 52;
    
              then (p2
    `2 ) 
    =  
    0 by 
    A217,
    A240,
    Lm9,
    TOPREAL1: 4;
    
              hence contradiction by
    A217,
    A236,
    EUCLID: 53;
    
            end;
    
            then
    
            
    
    A241: 
    {p10}
    <> (( 
    LSeg (p11,p2)) 
    /\ L3) by 
    ZFMISC_1: 31;
    
            ((
    LSeg (p11,p2)) 
    /\ L3) 
    c= (L4 
    /\ L3) by 
    A225,
    XBOOLE_1: 27;
    
            then ((
    LSeg (p11,p2)) 
    /\ L3) 
    =  
    {} by 
    A241,
    TOPREAL1: 16,
    ZFMISC_1: 33;
    
            hence (P1
    /\ P2) 
    = (( 
    {p1}
    \/ (( 
    LSeg (p1,p11)) 
    /\ L1)) 
    \/ ((( 
    LSeg (p11,p2)) 
    /\ ( 
    LSeg (p1,p01))) 
    \/  
    {p2})) by
    A229,
    A239;
    
          end;
    
        end;
    
        now
    
          per cases ;
    
            suppose
    
            
    
    A242: p1 
    = p01; 
    
            then
    
            
    
    A243: (( 
    LSeg (p11,p2)) 
    /\ ( 
    LSeg (p1,p01))) 
    = (( 
    LSeg (p11,p2)) 
    /\  
    {p1}) by
    RLTOPSP1: 70;
    
            p1
    in ( 
    LSeg (p11,p2)) implies contradiction by 
    A225,
    A242,
    Lm6,
    Lm8,
    Lm10,
    TOPREAL1: 3;
    
            then ((
    LSeg (p11,p2)) 
    /\ ( 
    LSeg (p1,p01))) 
    =  
    {} by 
    A243,
    Lm1;
    
            hence thesis by
    A230,
    A242,
    ENUMSET1: 1,
    TOPREAL1: 15;
    
          end;
    
            suppose
    
            
    
    A244: p1 
    = p11; 
    
            p11
    in ( 
    LSeg (p11,p2)) by 
    RLTOPSP1: 68;
    
            then
    
            
    
    A245: (( 
    LSeg (p11,p2)) 
    /\ ( 
    LSeg (p1,p01))) 
    <>  
    {} by 
    A244,
    Lm26,
    XBOOLE_0:def 4;
    
            ((
    LSeg (p1,p11)) 
    /\ L1) 
    = ( 
    {p1}
    /\ L1) by 
    A244,
    RLTOPSP1: 70;
    
            then
    
            
    
    A246: (( 
    LSeg (p1,p11)) 
    /\ L1) 
    =  
    {} by 
    A244,
    Lm1,
    Lm18;
    
            ((
    LSeg (p11,p2)) 
    /\ ( 
    LSeg (p1,p01))) 
    c= (L4 
    /\ L2) by 
    A11,
    A225,
    XBOOLE_1: 27;
    
            then ((
    LSeg (p11,p2)) 
    /\ ( 
    LSeg (p1,p01))) 
    =  
    {p1} by
    A244,
    A245,
    TOPREAL1: 18,
    ZFMISC_1: 33;
    
            
    
            hence (P1
    /\ P2) 
    = (( 
    {p1}
    \/  
    {p1})
    \/  
    {p2}) by
    A230,
    A246,
    XBOOLE_1: 4
    
            .=
    {p1, p2} by
    ENUMSET1: 1;
    
          end;
    
            suppose
    
            
    
    A247: p1 
    <> p11 & p1 
    <> p01; 
    
            now
    
              assume p11
    in (( 
    LSeg (p11,p2)) 
    /\ ( 
    LSeg (p1,p01))); 
    
              then
    
              
    
    A248: p11 
    in ( 
    LSeg (p01,p1)) by 
    XBOOLE_0:def 4;
    
              (p01
    `1 ) 
    <= (p1 
    `1 ) by 
    A13,
    A15,
    EUCLID: 52;
    
              then (p11
    `1 ) 
    <= (p1 
    `1 ) by 
    A248,
    TOPREAL1: 3;
    
              then (p1
    `1 ) 
    = 1 by 
    A13,
    A14,
    Lm10,
    XXREAL_0: 1;
    
              hence contradiction by
    A13,
    A16,
    A247,
    EUCLID: 53;
    
            end;
    
            then
    
            
    
    A249: 
    {p11}
    <> (( 
    LSeg (p11,p2)) 
    /\ ( 
    LSeg (p1,p01))) by 
    ZFMISC_1: 31;
    
            ((
    LSeg (p11,p2)) 
    /\ ( 
    LSeg (p1,p01))) 
    c= (L4 
    /\ L2) by 
    A11,
    A225,
    XBOOLE_1: 27;
    
            then
    
            
    
    A250: (( 
    LSeg (p11,p2)) 
    /\ ( 
    LSeg (p1,p01))) 
    =  
    {} by 
    A249,
    TOPREAL1: 18,
    ZFMISC_1: 33;
    
            now
    
              assume p01
    in (( 
    LSeg (p1,p11)) 
    /\ L1); 
    
              then
    
              
    
    A251: p01 
    in ( 
    LSeg (p1,p11)) by 
    XBOOLE_0:def 4;
    
              (p1
    `1 ) 
    <= (p11 
    `1 ) by 
    A13,
    A14,
    EUCLID: 52;
    
              then (p1
    `1 ) 
    =  
    0 by 
    A13,
    A15,
    A251,
    Lm6,
    TOPREAL1: 3;
    
              hence contradiction by
    A13,
    A16,
    A247,
    EUCLID: 53;
    
            end;
    
            then
    
            
    
    A252: 
    {p01}
    <> (( 
    LSeg (p1,p11)) 
    /\ L1) by 
    ZFMISC_1: 31;
    
            ((
    LSeg (p1,p11)) 
    /\ L1) 
    c= (L2 
    /\ L1) by 
    A8,
    XBOOLE_1: 27;
    
            then ((
    LSeg (p1,p11)) 
    /\ L1) 
    =  
    {} by 
    A252,
    TOPREAL1: 15,
    ZFMISC_1: 33;
    
            hence thesis by
    A230,
    A250,
    ENUMSET1: 1;
    
          end;
    
        end;
    
        hence thesis;
    
      end;
    
    end;
    
    
    
    
    
    Lm32: p1 
    <> p2 & p2 
    in  
    R^2-unit_square & p1 
    in ( 
    LSeg (p00,p10)) implies ex P1,P2 be non 
    empty  
    Subset of ( 
    TOP-REAL 2) st P1 
    is_an_arc_of (p1,p2) & P2 
    is_an_arc_of (p1,p2) & 
    R^2-unit_square  
    = (P1 
    \/ P2) & (P1 
    /\ P2) 
    =  
    {p1, p2}
    
    proof
    
      assume that
    
      
    
    A1: p1 
    <> p2 and 
    
      
    
    A2: p2 
    in  
    R^2-unit_square and 
    
      
    
    A3: p1 
    in ( 
    LSeg (p00,p10)); 
    
      
    
      
    
    A4: p2 
    in (L1 
    \/ L2) or p2 
    in (L3 
    \/ L4) by 
    A2,
    TOPREAL1:def 2,
    XBOOLE_0:def 3;
    
      
    
      
    
    A5: (( 
    LSeg (p10,p1)) 
    /\ L4) 
    c= (L3 
    /\ L4) by 
    A3,
    Lm24,
    TOPREAL1: 6,
    XBOOLE_1: 26;
    
      p00
    in ( 
    LSeg (p1,p00)) by 
    RLTOPSP1: 68;
    
      then
    
      
    
    A6: p00 
    in (( 
    LSeg (p1,p00)) 
    /\ L1) by 
    Lm20,
    XBOOLE_0:def 4;
    
      p10
    in ( 
    LSeg (p10,p1)) by 
    RLTOPSP1: 68;
    
      then
    
      
    
    A7: (( 
    LSeg (p10,p1)) 
    /\ L4) 
    <>  
    {} by 
    Lm25,
    XBOOLE_0:def 4;
    
      
    
      
    
    A8: (( 
    LSeg (p1,p00)) 
    /\ L1) 
    c= (L3 
    /\ L1) by 
    A3,
    Lm21,
    TOPREAL1: 6,
    XBOOLE_1: 26;
    
      
    
      
    
    A9: (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p1,p10))) 
    =  
    {p1} by
    A3,
    TOPREAL1: 8;
    
      
    
      
    
    A10: ( 
    LSeg (p00,p1)) 
    c= L3 by 
    A3,
    Lm21,
    TOPREAL1: 6;
    
      (L3
    /\ L2) 
    =  
    {} by 
    TOPREAL1: 19,
    XBOOLE_0:def 7;
    
      then
    
      
    
    A11: (( 
    LSeg (p1,p00)) 
    /\ L2) 
    =  
    {} by 
    A10,
    XBOOLE_1: 3,
    XBOOLE_1: 26;
    
      
    
      
    
    A12: ( 
    LSeg (p10,p1)) 
    c= L3 by 
    A3,
    Lm24,
    TOPREAL1: 6;
    
      (L3
    /\ L2) 
    =  
    {} by 
    TOPREAL1: 19,
    XBOOLE_0:def 7;
    
      then
    
      
    
    A13: (( 
    LSeg (p10,p1)) 
    /\ L2) 
    =  
    {} by 
    A12,
    XBOOLE_1: 3,
    XBOOLE_1: 26;
    
      consider p such that
    
      
    
    A14: p 
    = p1 and 
    
      
    
    A15: (p 
    `1 ) 
    <= 1 and 
    
      
    
    A16: (p 
    `1 ) 
    >=  
    0 and 
    
      
    
    A17: (p 
    `2 ) 
    =  
    0 by 
    A3,
    TOPREAL1: 13;
    
      per cases by
    A4,
    XBOOLE_0:def 3;
    
        suppose
    
        
    
    A18: p2 
    in L1; 
    
        
    
        
    
    A19: L2 
    is_an_arc_of (p11,p01) by 
    Lm6,
    Lm10,
    TOPREAL1: 9;
    
        L4
    is_an_arc_of (p10,p11) by 
    Lm9,
    Lm11,
    TOPREAL1: 9;
    
        then
    
        
    
    A20: (L4 
    \/ L2) 
    is_an_arc_of (p10,p01) by 
    A19,
    TOPREAL1: 2,
    TOPREAL1: 18;
    
        (L3
    /\ L2) 
    =  
    {} by 
    TOPREAL1: 19,
    XBOOLE_0:def 7;
    
        then
    
        
    
    A21: (( 
    LSeg (p1,p00)) 
    /\ L2) 
    =  
    {} by 
    A10,
    XBOOLE_1: 3,
    XBOOLE_1: 26;
    
        take P1 = ((
    LSeg (p1,p00)) 
    \/ ( 
    LSeg (p00,p2))), P2 = (( 
    LSeg (p1,p10)) 
    \/ ((L4 
    \/ L2) 
    \/ ( 
    LSeg (p01,p2)))); 
    
        
    
        
    
    A22: (( 
    LSeg (p1,p00)) 
    \/ ( 
    LSeg (p1,p10))) 
    = L3 by 
    A3,
    TOPREAL1: 5;
    
        p01
    in ( 
    LSeg (p01,p2)) by 
    RLTOPSP1: 68;
    
        then
    
        
    
    A23: p01 
    in (L2 
    /\ ( 
    LSeg (p01,p2))) by 
    Lm23,
    XBOOLE_0:def 4;
    
        
    
        
    
    A24: p00 
    in ( 
    LSeg (p00,p2)) by 
    RLTOPSP1: 68;
    
        p00
    in ( 
    LSeg (p1,p00)) by 
    RLTOPSP1: 68;
    
        then
    
        
    
    A25: p00 
    in (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p00,p2))) by 
    A24,
    XBOOLE_0:def 4;
    
        
    
        
    
    A26: ( 
    LSeg (p00,p2)) 
    c= L1 by 
    A18,
    Lm20,
    TOPREAL1: 6;
    
        then ((
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p00,p2))) 
    c= (L3 
    /\ L1) by 
    A10,
    XBOOLE_1: 27;
    
        then
    
        
    
    A27: (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p00,p2))) 
    =  
    {p00} by
    A25,
    TOPREAL1: 17,
    ZFMISC_1: 33;
    
        
    
        
    
    A28: ex q st q 
    = p2 & (q 
    `1 ) 
    =  
    0 & (q 
    `2 ) 
    <= 1 & (q 
    `2 ) 
    >=  
    0 by 
    A18,
    TOPREAL1: 13;
    
        now
    
          
    
          
    
    A29: (p2 
    `2 ) 
    <= (p01 
    `2 ) by 
    A28,
    EUCLID: 52;
    
          assume
    
          
    
    A30: p00 
    in (( 
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p01,p2))); 
    
          then
    
          
    
    A31: p00 
    in ( 
    LSeg (p1,p10)) by 
    XBOOLE_0:def 4;
    
          p00
    in ( 
    LSeg (p2,p01)) by 
    A30,
    XBOOLE_0:def 4;
    
          then
    
          
    
    A32: 
    0  
    = (p2 
    `2 ) by 
    A28,
    A29,
    Lm5,
    TOPREAL1: 4;
    
          (p1
    `1 ) 
    <= (p10 
    `1 ) by 
    A14,
    A15,
    EUCLID: 52;
    
          then
    0  
    = (p1 
    `1 ) by 
    A14,
    A16,
    A31,
    Lm4,
    TOPREAL1: 3;
    
          
    
          then p1
    = p00 by 
    A14,
    A17,
    EUCLID: 53
    
          .= p2 by
    A28,
    A32,
    EUCLID: 53;
    
          hence contradiction by
    A1;
    
        end;
    
        then
    
        
    
    A33: 
    {p00}
    <> (( 
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p01,p2))) by 
    ZFMISC_1: 31;
    
        p1
    <> p00 or p00 
    <> p2 by 
    A1;
    
        hence P1
    is_an_arc_of (p1,p2) by 
    A27,
    TOPREAL1: 12;
    
        
    
        
    
    A34: 
    {p1}
    = (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p1,p10))) by 
    A3,
    TOPREAL1: 8;
    
        (L1
    /\ L4) 
    =  
    {} by 
    TOPREAL1: 20,
    XBOOLE_0:def 7;
    
        then
    
        
    
    A35: (( 
    LSeg (p00,p2)) 
    /\ L4) 
    =  
    {} by 
    A26,
    XBOOLE_1: 3,
    XBOOLE_1: 26;
    
        
    
        
    
    A36: ( 
    LSeg (p2,p01)) 
    c= L1 by 
    A18,
    Lm22,
    TOPREAL1: 6;
    
        then
    
        
    
    A37: (L2 
    /\ ( 
    LSeg (p01,p2))) 
    c= (L2 
    /\ L1) by 
    XBOOLE_1: 27;
    
        
    
        
    
    A38: (L4 
    /\ ( 
    LSeg (p01,p2))) 
    =  
    {} by 
    A36,
    Lm3,
    XBOOLE_1: 3,
    XBOOLE_1: 26;
    
        ((L4
    \/ L2) 
    /\ ( 
    LSeg (p01,p2))) 
    = ((L4 
    /\ ( 
    LSeg (p01,p2))) 
    \/ (L2 
    /\ ( 
    LSeg (p01,p2)))) by 
    XBOOLE_1: 23
    
        .=
    {p01} by
    A38,
    A37,
    A23,
    TOPREAL1: 15,
    ZFMISC_1: 33;
    
        then
    
        
    
    A39: ((L4 
    \/ L2) 
    \/ ( 
    LSeg (p01,p2))) 
    is_an_arc_of (p10,p2) by 
    A20,
    TOPREAL1: 10;
    
        
    
        
    
    A40: 
    {p2}
    = (( 
    LSeg (p00,p2)) 
    /\ ( 
    LSeg (p01,p2))) by 
    A18,
    TOPREAL1: 8;
    
        
    
        
    
    A41: (( 
    LSeg (p01,p2)) 
    \/ ( 
    LSeg (p00,p2))) 
    = L1 by 
    A18,
    TOPREAL1: 5;
    
        ((
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p01,p2))) 
    c= (L3 
    /\ L1) by 
    A12,
    A36,
    XBOOLE_1: 27;
    
        then
    
        
    
    A42: (( 
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p01,p2))) 
    =  
    {} by 
    A33,
    TOPREAL1: 17,
    ZFMISC_1: 33;
    
        ((
    LSeg (p1,p10)) 
    /\ ((L4 
    \/ L2) 
    \/ ( 
    LSeg (p01,p2)))) 
    = ((( 
    LSeg (p1,p10)) 
    /\ (L4 
    \/ L2)) 
    \/ (( 
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p01,p2)))) by 
    XBOOLE_1: 23
    
        .= (((
    LSeg (p1,p10)) 
    /\ L4) 
    \/ (( 
    LSeg (p10,p1)) 
    /\ L2)) by 
    A42,
    XBOOLE_1: 23
    
        .=
    {p10} by
    A13,
    A5,
    A7,
    TOPREAL1: 16,
    ZFMISC_1: 33;
    
        hence P2
    is_an_arc_of (p1,p2) by 
    A39,
    TOPREAL1: 11;
    
        
    
        thus (P1
    \/ P2) 
    = (( 
    LSeg (p00,p2)) 
    \/ (( 
    LSeg (p1,p00)) 
    \/ (( 
    LSeg (p1,p10)) 
    \/ ((L4 
    \/ L2) 
    \/ ( 
    LSeg (p01,p2)))))) by 
    XBOOLE_1: 4
    
        .= ((
    LSeg (p00,p2)) 
    \/ (L3 
    \/ ((L4 
    \/ L2) 
    \/ ( 
    LSeg (p01,p2))))) by 
    A22,
    XBOOLE_1: 4
    
        .= ((
    LSeg (p00,p2)) 
    \/ ((L3 
    \/ (L4 
    \/ L2)) 
    \/ ( 
    LSeg (p01,p2)))) by 
    XBOOLE_1: 4
    
        .= ((
    LSeg (p00,p2)) 
    \/ (((L3 
    \/ L4) 
    \/ L2) 
    \/ ( 
    LSeg (p01,p2)))) by 
    XBOOLE_1: 4
    
        .= ((
    LSeg (p00,p2)) 
    \/ ((L3 
    \/ L4) 
    \/ (L2 
    \/ ( 
    LSeg (p01,p2))))) by 
    XBOOLE_1: 4
    
        .= (((L2
    \/ ( 
    LSeg (p01,p2))) 
    \/ ( 
    LSeg (p00,p2))) 
    \/ (L3 
    \/ L4)) by 
    XBOOLE_1: 4
    
        .=
    R^2-unit_square by 
    A41,
    TOPREAL1:def 2,
    XBOOLE_1: 4;
    
        
    
        
    
    A43: (P1 
    /\ P2) 
    = ((( 
    LSeg (p1,p00)) 
    /\ (( 
    LSeg (p1,p10)) 
    \/ ((L4 
    \/ L2) 
    \/ ( 
    LSeg (p01,p2))))) 
    \/ (( 
    LSeg (p00,p2)) 
    /\ (( 
    LSeg (p1,p10)) 
    \/ ((L4 
    \/ L2) 
    \/ ( 
    LSeg (p01,p2)))))) by 
    XBOOLE_1: 23
    
        .= ((((
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p1,p10))) 
    \/ (( 
    LSeg (p1,p00)) 
    /\ ((L4 
    \/ L2) 
    \/ ( 
    LSeg (p01,p2))))) 
    \/ (( 
    LSeg (p00,p2)) 
    /\ (( 
    LSeg (p1,p10)) 
    \/ ((L4 
    \/ L2) 
    \/ ( 
    LSeg (p01,p2)))))) by 
    XBOOLE_1: 23
    
        .= ((
    {p1}
    \/ ((( 
    LSeg (p1,p00)) 
    /\ (L4 
    \/ L2)) 
    \/ (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p01,p2))))) 
    \/ (( 
    LSeg (p00,p2)) 
    /\ (( 
    LSeg (p1,p10)) 
    \/ ((L4 
    \/ L2) 
    \/ ( 
    LSeg (p01,p2)))))) by 
    A34,
    XBOOLE_1: 23
    
        .= ((
    {p1}
    \/ (((( 
    LSeg (p1,p00)) 
    /\ L4) 
    \/ (( 
    LSeg (p1,p00)) 
    /\ L2)) 
    \/ (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p01,p2))))) 
    \/ (( 
    LSeg (p00,p2)) 
    /\ (( 
    LSeg (p1,p10)) 
    \/ ((L4 
    \/ L2) 
    \/ ( 
    LSeg (p01,p2)))))) by 
    XBOOLE_1: 23
    
        .= ((
    {p1}
    \/ ((( 
    LSeg (p1,p00)) 
    /\ L4) 
    \/ (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p01,p2))))) 
    \/ ((( 
    LSeg (p00,p2)) 
    /\ ( 
    LSeg (p1,p10))) 
    \/ (( 
    LSeg (p00,p2)) 
    /\ ((L4 
    \/ L2) 
    \/ ( 
    LSeg (p01,p2)))))) by 
    A21,
    XBOOLE_1: 23
    
        .= ((
    {p1}
    \/ ((( 
    LSeg (p1,p00)) 
    /\ L4) 
    \/ (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p01,p2))))) 
    \/ ((( 
    LSeg (p00,p2)) 
    /\ ( 
    LSeg (p1,p10))) 
    \/ ((( 
    LSeg (p00,p2)) 
    /\ (L4 
    \/ L2)) 
    \/  
    {p2}))) by
    A40,
    XBOOLE_1: 23
    
        .= ((
    {p1}
    \/ ((( 
    LSeg (p1,p00)) 
    /\ L4) 
    \/ (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p01,p2))))) 
    \/ ((( 
    LSeg (p00,p2)) 
    /\ ( 
    LSeg (p1,p10))) 
    \/ (((( 
    LSeg (p00,p2)) 
    /\ L4) 
    \/ (( 
    LSeg (p00,p2)) 
    /\ L2)) 
    \/  
    {p2}))) by
    XBOOLE_1: 23
    
        .= ((
    {p1}
    \/ ((( 
    LSeg (p1,p00)) 
    /\ L4) 
    \/ (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p01,p2))))) 
    \/ ((( 
    LSeg (p00,p2)) 
    /\ ( 
    LSeg (p1,p10))) 
    \/ ((( 
    LSeg (p00,p2)) 
    /\ L2) 
    \/  
    {p2}))) by
    A35;
    
        
    
    A44: 
    
        now
    
          per cases ;
    
            suppose
    
            
    
    A45: p1 
    = p00; 
    
            
    
            
    
    A46: p1 
    in ( 
    LSeg (p1,p10)) by 
    RLTOPSP1: 68;
    
            p1
    in ( 
    LSeg (p00,p2)) by 
    A45,
    RLTOPSP1: 68;
    
            then
    
            
    
    A47: (( 
    LSeg (p00,p2)) 
    /\ ( 
    LSeg (p1,p10))) 
    <>  
    {} by 
    A46,
    XBOOLE_0:def 4;
    
            ((
    LSeg (p1,p00)) 
    /\ L4) 
    = ( 
    {p00}
    /\ L4) by 
    A45,
    RLTOPSP1: 70;
    
            then
    
            
    
    A48: (( 
    LSeg (p1,p00)) 
    /\ L4) 
    =  
    {} by 
    Lm1,
    Lm12;
    
            ((
    LSeg (p00,p2)) 
    /\ ( 
    LSeg (p1,p10))) 
    c=  
    {p1} by
    A18,
    A45,
    Lm20,
    TOPREAL1: 6,
    TOPREAL1: 17,
    XBOOLE_1: 26;
    
            then ((
    LSeg (p00,p2)) 
    /\ ( 
    LSeg (p1,p10))) 
    =  
    {p1} by
    A47,
    ZFMISC_1: 33;
    
            
    
            hence (P1
    /\ P2) 
    = (( 
    {p1}
    \/ ( 
    {p1}
    \/ (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p01,p2))))) 
    \/ ((( 
    LSeg (p00,p2)) 
    /\ L2) 
    \/  
    {p2})) by
    A43,
    A48,
    XBOOLE_1: 4
    
            .= (((
    {p1}
    \/  
    {p1})
    \/ (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p01,p2)))) 
    \/ ((( 
    LSeg (p00,p2)) 
    /\ L2) 
    \/  
    {p2})) by
    XBOOLE_1: 4
    
            .= ((
    {p1}
    \/ (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p01,p2)))) 
    \/ ((( 
    LSeg (p00,p2)) 
    /\ L2) 
    \/  
    {p2}));
    
          end;
    
            suppose
    
            
    
    A49: p1 
    = p10; 
    
            then
    
            
    
    A50: (( 
    LSeg (p00,p2)) 
    /\ ( 
    LSeg (p1,p10))) 
    = (( 
    LSeg (p00,p2)) 
    /\  
    {p10}) by
    RLTOPSP1: 70;
    
             not p10
    in ( 
    LSeg (p00,p2)) by 
    A26,
    Lm4,
    Lm6,
    Lm8,
    TOPREAL1: 3;
    
            then ((
    LSeg (p00,p2)) 
    /\ ( 
    LSeg (p1,p10))) 
    =  
    {} by 
    A50,
    Lm1;
    
            
    
            hence (P1
    /\ P2) 
    = ((( 
    {p1}
    \/  
    {p1})
    \/ (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p01,p2)))) 
    \/ ((( 
    LSeg (p00,p2)) 
    /\ L2) 
    \/  
    {p2})) by
    A43,
    A49,
    TOPREAL1: 16,
    XBOOLE_1: 4
    
            .= ((
    {p1}
    \/ (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p01,p2)))) 
    \/ ((( 
    LSeg (p00,p2)) 
    /\ L2) 
    \/  
    {p2}));
    
          end;
    
            suppose
    
            
    
    A51: p1 
    <> p10 & p1 
    <> p00; 
    
            now
    
              assume p00
    in (( 
    LSeg (p00,p2)) 
    /\ ( 
    LSeg (p1,p10))); 
    
              then
    
              
    
    A52: p00 
    in ( 
    LSeg (p1,p10)) by 
    XBOOLE_0:def 4;
    
              (p1
    `1 ) 
    <= (p10 
    `1 ) by 
    A14,
    A15,
    EUCLID: 52;
    
              then
    0  
    = (p1 
    `1 ) by 
    A14,
    A16,
    A52,
    Lm4,
    TOPREAL1: 3;
    
              hence contradiction by
    A14,
    A17,
    A51,
    EUCLID: 53;
    
            end;
    
            then
    
            
    
    A53: 
    {p00}
    <> (( 
    LSeg (p00,p2)) 
    /\ ( 
    LSeg (p1,p10))) by 
    ZFMISC_1: 31;
    
            ((
    LSeg (p00,p2)) 
    /\ ( 
    LSeg (p1,p10))) 
    c=  
    {p00} by
    A12,
    A26,
    TOPREAL1: 17,
    XBOOLE_1: 27;
    
            then
    
            
    
    A54: (( 
    LSeg (p00,p2)) 
    /\ ( 
    LSeg (p1,p10))) 
    =  
    {} by 
    A53,
    ZFMISC_1: 33;
    
            now
    
              assume p10
    in (( 
    LSeg (p1,p00)) 
    /\ L4); 
    
              then
    
              
    
    A55: p10 
    in ( 
    LSeg (p00,p1)) by 
    XBOOLE_0:def 4;
    
              (p00
    `1 ) 
    <= (p1 
    `1 ) by 
    A14,
    A16,
    EUCLID: 52;
    
              then (p10
    `1 ) 
    <= (p1 
    `1 ) by 
    A55,
    TOPREAL1: 3;
    
              then (p1
    `1 ) 
    = 1 by 
    A14,
    A15,
    Lm8,
    XXREAL_0: 1;
    
              hence contradiction by
    A14,
    A17,
    A51,
    EUCLID: 53;
    
            end;
    
            then
    
            
    
    A56: 
    {p10}
    <> (( 
    LSeg (p1,p00)) 
    /\ L4) by 
    ZFMISC_1: 31;
    
            ((
    LSeg (p1,p00)) 
    /\ L4) 
    c=  
    {p10} by
    A3,
    Lm21,
    TOPREAL1: 6,
    TOPREAL1: 16,
    XBOOLE_1: 26;
    
            then ((
    LSeg (p1,p00)) 
    /\ L4) 
    =  
    {} by 
    A56,
    ZFMISC_1: 33;
    
            hence (P1
    /\ P2) 
    = (( 
    {p1}
    \/ (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p01,p2)))) 
    \/ ((( 
    LSeg (p00,p2)) 
    /\ L2) 
    \/  
    {p2})) by
    A43,
    A54;
    
          end;
    
        end;
    
        now
    
          per cases ;
    
            suppose
    
            
    
    A57: p2 
    = p00; 
    
            p00
    in ( 
    LSeg (p1,p00)) by 
    RLTOPSP1: 68;
    
            then
    
            
    
    A58: (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p01,p2))) 
    <>  
    {} by 
    A57,
    Lm20,
    XBOOLE_0:def 4;
    
            ((
    LSeg (p00,p2)) 
    /\ L2) 
    = ( 
    {p00}
    /\ L2) by 
    A57,
    RLTOPSP1: 70;
    
            then
    
            
    
    A59: (( 
    LSeg (p00,p2)) 
    /\ L2) 
    =  
    {} by 
    Lm1,
    Lm13;
    
            ((
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p01,p2))) 
    c= (L3 
    /\ L1) by 
    A10,
    A36,
    XBOOLE_1: 27;
    
            then ((
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p01,p2))) 
    =  
    {p2} by
    A57,
    A58,
    TOPREAL1: 17,
    ZFMISC_1: 33;
    
            
    
            hence (P1
    /\ P2) 
    = ( 
    {p1}
    \/ ( 
    {p2}
    \/  
    {p2})) by
    A44,
    A59,
    XBOOLE_1: 4
    
            .=
    {p1, p2} by
    ENUMSET1: 1;
    
            hence thesis;
    
          end;
    
            suppose
    
            
    
    A60: p2 
    = p01; 
    
            then
    
            
    
    A61: (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p01,p2))) 
    = (( 
    LSeg (p1,p00)) 
    /\  
    {p01}) by
    RLTOPSP1: 70;
    
             not p01
    in ( 
    LSeg (p1,p00)) by 
    A10,
    Lm5,
    Lm7,
    Lm9,
    TOPREAL1: 4;
    
            then
    
            
    
    A62: (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p01,p2))) 
    =  
    {} by 
    A61,
    Lm1;
    
            hence thesis by
    A44,
    A60,
    ENUMSET1: 1,
    TOPREAL1: 15;
    
            thus thesis by
    A44,
    A60,
    A62,
    ENUMSET1: 1,
    TOPREAL1: 15;
    
          end;
    
            suppose
    
            
    
    A63: p2 
    <> p01 & p2 
    <> p00; 
    
            now
    
              assume p01
    in (( 
    LSeg (p00,p2)) 
    /\ L2); 
    
              then
    
              
    
    A64: p01 
    in ( 
    LSeg (p00,p2)) by 
    XBOOLE_0:def 4;
    
              (p00
    `2 ) 
    <= (p2 
    `2 ) by 
    A28,
    EUCLID: 52;
    
              then (p01
    `2 ) 
    <= (p2 
    `2 ) by 
    A64,
    TOPREAL1: 4;
    
              then 1
    = (p2 
    `2 ) by 
    A28,
    Lm7,
    XXREAL_0: 1;
    
              hence contradiction by
    A28,
    A63,
    EUCLID: 53;
    
            end;
    
            then
    
            
    
    A65: 
    {p01}
    <> (( 
    LSeg (p00,p2)) 
    /\ L2) by 
    ZFMISC_1: 31;
    
            ((
    LSeg (p00,p2)) 
    /\ L2) 
    c=  
    {p01} by
    A18,
    Lm20,
    TOPREAL1: 6,
    TOPREAL1: 15,
    XBOOLE_1: 26;
    
            then
    
            
    
    A66: (( 
    LSeg (p00,p2)) 
    /\ L2) 
    =  
    {} by 
    A65,
    ZFMISC_1: 33;
    
            now
    
              assume p00
    in (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p01,p2))); 
    
              then
    
              
    
    A67: p00 
    in ( 
    LSeg (p2,p01)) by 
    XBOOLE_0:def 4;
    
              (p2
    `2 ) 
    <= (p01 
    `2 ) by 
    A28,
    EUCLID: 52;
    
              then (p2
    `2 ) 
    =  
    0 by 
    A28,
    A67,
    Lm5,
    TOPREAL1: 4;
    
              hence contradiction by
    A28,
    A63,
    EUCLID: 53;
    
            end;
    
            then
    
            
    
    A68: 
    {p00}
    <> (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p01,p2))) by 
    ZFMISC_1: 31;
    
            ((
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p01,p2))) 
    c= (L3 
    /\ L1) by 
    A10,
    A36,
    XBOOLE_1: 27;
    
            then
    
            
    
    A69: (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p01,p2))) 
    =  
    {} by 
    A68,
    TOPREAL1: 17,
    ZFMISC_1: 33;
    
            hence thesis by
    A44,
    A66,
    ENUMSET1: 1;
    
            thus thesis by
    A44,
    A69,
    A66,
    ENUMSET1: 1;
    
          end;
    
        end;
    
        hence thesis;
    
      end;
    
        suppose
    
        
    
    A70: p2 
    in L2; 
    
        then
    
        
    
    A71: ( 
    LSeg (p2,p11)) 
    c= L2 by 
    Lm26,
    TOPREAL1: 6;
    
        then
    
        
    
    A72: (( 
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p11,p2))) 
    =  
    {} by 
    A12,
    Lm2,
    XBOOLE_1: 3,
    XBOOLE_1: 27;
    
        
    
        
    
    A73: ( 
    LSeg (p2,p01)) 
    c= L2 by 
    A70,
    Lm23,
    TOPREAL1: 6;
    
        then
    
        
    
    A74: (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p01,p2))) 
    =  
    {} by 
    A10,
    Lm2,
    XBOOLE_1: 3,
    XBOOLE_1: 27;
    
        take P1 = (((
    LSeg (p1,p00)) 
    \/ L1) 
    \/ ( 
    LSeg (p01,p2))), P2 = ((( 
    LSeg (p1,p10)) 
    \/ L4) 
    \/ ( 
    LSeg (p11,p2))); 
    
        p01
    in ( 
    LSeg (p01,p2)) by 
    RLTOPSP1: 68;
    
        then
    
        
    
    A75: (L1 
    /\ ( 
    LSeg (p01,p2))) 
    <>  
    {} by 
    Lm22,
    XBOOLE_0:def 4;
    
        (L1
    /\ ( 
    LSeg (p01,p2))) 
    c=  
    {p01} by
    A70,
    Lm23,
    TOPREAL1: 6,
    TOPREAL1: 15,
    XBOOLE_1: 26;
    
        then (L1
    /\ ( 
    LSeg (p01,p2))) 
    =  
    {p01} by
    A75,
    ZFMISC_1: 33;
    
        then
    
        
    
    A76: (L1 
    \/ ( 
    LSeg (p01,p2))) 
    is_an_arc_of (p00,p2) by 
    Lm5,
    Lm7,
    TOPREAL1: 12;
    
        ((
    LSeg (p1,p00)) 
    /\ (L1 
    \/ ( 
    LSeg (p01,p2)))) 
    = ((( 
    LSeg (p1,p00)) 
    /\ L1) 
    \/ (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p01,p2)))) by 
    XBOOLE_1: 23
    
        .=
    {p00} by
    A8,
    A6,
    A74,
    TOPREAL1: 17,
    ZFMISC_1: 33;
    
        then ((
    LSeg (p1,p00)) 
    \/ (L1 
    \/ ( 
    LSeg (p01,p2)))) 
    is_an_arc_of (p1,p2) by 
    A76,
    TOPREAL1: 11;
    
        hence P1
    is_an_arc_of (p1,p2) by 
    XBOOLE_1: 4;
    
        p11
    in ( 
    LSeg (p11,p2)) by 
    RLTOPSP1: 68;
    
        then
    
        
    
    A77: (L4 
    /\ ( 
    LSeg (p11,p2))) 
    <>  
    {} by 
    Lm27,
    XBOOLE_0:def 4;
    
        (L4
    /\ ( 
    LSeg (p11,p2))) 
    c= (L4 
    /\ L2) by 
    A70,
    Lm26,
    TOPREAL1: 6,
    XBOOLE_1: 26;
    
        then (L4
    /\ ( 
    LSeg (p11,p2))) 
    =  
    {p11} by
    A77,
    TOPREAL1: 18,
    ZFMISC_1: 33;
    
        then
    
        
    
    A78: (L4 
    \/ ( 
    LSeg (p11,p2))) 
    is_an_arc_of (p10,p2) by 
    Lm9,
    Lm11,
    TOPREAL1: 12;
    
        ((
    LSeg (p1,p10)) 
    /\ (L4 
    \/ ( 
    LSeg (p11,p2)))) 
    = ((( 
    LSeg (p1,p10)) 
    /\ L4) 
    \/ (( 
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p11,p2)))) by 
    XBOOLE_1: 23
    
        .=
    {p10} by
    A5,
    A7,
    A72,
    TOPREAL1: 16,
    ZFMISC_1: 33;
    
        then ((
    LSeg (p1,p10)) 
    \/ (L4 
    \/ ( 
    LSeg (p11,p2)))) 
    is_an_arc_of (p1,p2) by 
    A78,
    TOPREAL1: 11;
    
        hence P2
    is_an_arc_of (p1,p2) by 
    XBOOLE_1: 4;
    
        
    
        thus
    R^2-unit_square  
    = ((L1 
    \/ (( 
    LSeg (p01,p2)) 
    \/ ( 
    LSeg (p11,p2)))) 
    \/ (L3 
    \/ L4)) by 
    A70,
    TOPREAL1: 5,
    TOPREAL1:def 2
    
        .= (((L1
    \/ ( 
    LSeg (p01,p2))) 
    \/ ( 
    LSeg (p11,p2))) 
    \/ (L3 
    \/ L4)) by 
    XBOOLE_1: 4
    
        .= ((L1
    \/ ( 
    LSeg (p01,p2))) 
    \/ ((L3 
    \/ L4) 
    \/ ( 
    LSeg (p11,p2)))) by 
    XBOOLE_1: 4
    
        .= ((L1
    \/ ( 
    LSeg (p01,p2))) 
    \/ (L3 
    \/ (L4 
    \/ ( 
    LSeg (p11,p2))))) by 
    XBOOLE_1: 4
    
        .= ((L1
    \/ ( 
    LSeg (p01,p2))) 
    \/ ((( 
    LSeg (p1,p00)) 
    \/ ( 
    LSeg (p1,p10))) 
    \/ (L4 
    \/ ( 
    LSeg (p11,p2))))) by 
    A3,
    TOPREAL1: 5
    
        .= ((L1
    \/ ( 
    LSeg (p01,p2))) 
    \/ (( 
    LSeg (p1,p00)) 
    \/ (( 
    LSeg (p1,p10)) 
    \/ (L4 
    \/ ( 
    LSeg (p11,p2)))))) by 
    XBOOLE_1: 4
    
        .= ((L1
    \/ ( 
    LSeg (p01,p2))) 
    \/ (( 
    LSeg (p1,p00)) 
    \/ ((( 
    LSeg (p1,p10)) 
    \/ L4) 
    \/ ( 
    LSeg (p11,p2))))) by 
    XBOOLE_1: 4
    
        .= (((
    LSeg (p1,p00)) 
    \/ (L1 
    \/ ( 
    LSeg (p01,p2)))) 
    \/ ((( 
    LSeg (p1,p10)) 
    \/ L4) 
    \/ ( 
    LSeg (p11,p2)))) by 
    XBOOLE_1: 4
    
        .= (P1
    \/ P2) by 
    XBOOLE_1: 4;
    
        
    
        
    
    A79: ex q st q 
    = p2 & (q 
    `1 ) 
    <= 1 & (q 
    `1 ) 
    >=  
    0 & (q 
    `2 ) 
    = 1 by 
    A70,
    TOPREAL1: 13;
    
        (L3
    /\ L2) 
    =  
    {} by 
    TOPREAL1: 19,
    XBOOLE_0:def 7;
    
        then
    
        
    
    A80: (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p11,p2))) 
    =  
    {} by 
    A10,
    A71,
    XBOOLE_1: 3,
    XBOOLE_1: 27;
    
        
    
        
    
    A81: (( 
    LSeg (p01,p2)) 
    /\ ( 
    LSeg (p1,p10))) 
    =  
    {} by 
    A12,
    A73,
    Lm2,
    XBOOLE_1: 3,
    XBOOLE_1: 27;
    
        
    
        
    
    A82: (( 
    LSeg (p01,p2)) 
    /\ ( 
    LSeg (p11,p2))) 
    =  
    {p2} by
    A70,
    TOPREAL1: 8;
    
        
    
        
    
    A83: (P1 
    /\ P2) 
    = (((( 
    LSeg (p1,p00)) 
    \/ L1) 
    /\ ((( 
    LSeg (p1,p10)) 
    \/ L4) 
    \/ ( 
    LSeg (p11,p2)))) 
    \/ (( 
    LSeg (p01,p2)) 
    /\ ((( 
    LSeg (p1,p10)) 
    \/ L4) 
    \/ ( 
    LSeg (p11,p2))))) by 
    XBOOLE_1: 23
    
        .= ((((
    LSeg (p1,p00)) 
    \/ L1) 
    /\ ((( 
    LSeg (p1,p10)) 
    \/ L4) 
    \/ ( 
    LSeg (p11,p2)))) 
    \/ ((( 
    LSeg (p01,p2)) 
    /\ (( 
    LSeg (p1,p10)) 
    \/ L4)) 
    \/  
    {p2})) by
    A82,
    XBOOLE_1: 23
    
        .= ((((
    LSeg (p1,p00)) 
    \/ L1) 
    /\ ((( 
    LSeg (p1,p10)) 
    \/ L4) 
    \/ ( 
    LSeg (p11,p2)))) 
    \/ (((( 
    LSeg (p01,p2)) 
    /\ ( 
    LSeg (p1,p10))) 
    \/ (( 
    LSeg (p01,p2)) 
    /\ L4)) 
    \/  
    {p2})) by
    XBOOLE_1: 23
    
        .= ((((
    LSeg (p1,p00)) 
    /\ ((( 
    LSeg (p1,p10)) 
    \/ L4) 
    \/ ( 
    LSeg (p11,p2)))) 
    \/ (L1 
    /\ ((( 
    LSeg (p1,p10)) 
    \/ L4) 
    \/ ( 
    LSeg (p11,p2))))) 
    \/ ((( 
    LSeg (p01,p2)) 
    /\ L4) 
    \/  
    {p2})) by
    A81,
    XBOOLE_1: 23
    
        .= (((((
    LSeg (p1,p00)) 
    /\ (( 
    LSeg (p1,p10)) 
    \/ L4)) 
    \/ (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p11,p2)))) 
    \/ (L1 
    /\ ((( 
    LSeg (p1,p10)) 
    \/ L4) 
    \/ ( 
    LSeg (p11,p2))))) 
    \/ ((( 
    LSeg (p01,p2)) 
    /\ L4) 
    \/  
    {p2})) by
    XBOOLE_1: 23
    
        .= (((
    {p1}
    \/ (( 
    LSeg (p1,p00)) 
    /\ L4)) 
    \/ (L1 
    /\ ((( 
    LSeg (p1,p10)) 
    \/ L4) 
    \/ ( 
    LSeg (p11,p2))))) 
    \/ ((( 
    LSeg (p01,p2)) 
    /\ L4) 
    \/  
    {p2})) by
    A9,
    A80,
    XBOOLE_1: 23
    
        .= (((
    {p1}
    \/ (( 
    LSeg (p1,p00)) 
    /\ L4)) 
    \/ ((L1 
    /\ (( 
    LSeg (p1,p10)) 
    \/ L4)) 
    \/ (L1 
    /\ ( 
    LSeg (p11,p2))))) 
    \/ ((( 
    LSeg (p01,p2)) 
    /\ L4) 
    \/  
    {p2})) by
    XBOOLE_1: 23
    
        .= (((
    {p1}
    \/ (( 
    LSeg (p1,p00)) 
    /\ L4)) 
    \/ (((L1 
    /\ ( 
    LSeg (p1,p10))) 
    \/ (L1 
    /\ L4)) 
    \/ (L1 
    /\ ( 
    LSeg (p11,p2))))) 
    \/ ((( 
    LSeg (p01,p2)) 
    /\ L4) 
    \/  
    {p2})) by
    XBOOLE_1: 23
    
        .= (((
    {p1}
    \/ (( 
    LSeg (p1,p00)) 
    /\ L4)) 
    \/ ((L1 
    /\ ( 
    LSeg (p1,p10))) 
    \/ (L1 
    /\ ( 
    LSeg (p11,p2))))) 
    \/ ((( 
    LSeg (p01,p2)) 
    /\ L4) 
    \/  
    {p2})) by
    Lm3;
    
        
    
    A84: 
    
        now
    
          per cases ;
    
            suppose
    
            
    
    A85: p1 
    = p00; 
    
            then ((
    LSeg (p1,p00)) 
    /\ L4) 
    = ( 
    {p00}
    /\ L4) by 
    RLTOPSP1: 70;
    
            then ((
    LSeg (p1,p00)) 
    /\ L4) 
    =  
    {} by 
    Lm1,
    Lm12;
    
            
    
            hence (P1
    /\ P2) 
    = ((( 
    {p1}
    \/  
    {p1})
    \/ (L1 
    /\ ( 
    LSeg (p11,p2)))) 
    \/ ((( 
    LSeg (p01,p2)) 
    /\ L4) 
    \/  
    {p2})) by
    A83,
    A85,
    TOPREAL1: 17,
    XBOOLE_1: 4
    
            .= ((
    {p1}
    \/ (L1 
    /\ ( 
    LSeg (p11,p2)))) 
    \/ ((( 
    LSeg (p01,p2)) 
    /\ L4) 
    \/  
    {p2}));
    
          end;
    
            suppose
    
            
    
    A86: p1 
    = p10; 
    
            then (L1
    /\ ( 
    LSeg (p1,p10))) 
    = (L1 
    /\  
    {p10}) by
    RLTOPSP1: 70;
    
            then (L1
    /\ ( 
    LSeg (p1,p10))) 
    =  
    {} by 
    Lm1,
    Lm16;
    
            hence (P1
    /\ P2) 
    = (( 
    {p1}
    \/ (L1 
    /\ ( 
    LSeg (p11,p2)))) 
    \/ ((( 
    LSeg (p01,p2)) 
    /\ L4) 
    \/  
    {p2})) by
    A83,
    A86,
    TOPREAL1: 16;
    
          end;
    
            suppose
    
            
    
    A87: p1 
    <> p10 & p1 
    <> p00; 
    
            now
    
              assume p00
    in (L1 
    /\ ( 
    LSeg (p1,p10))); 
    
              then
    
              
    
    A88: p00 
    in ( 
    LSeg (p1,p10)) by 
    XBOOLE_0:def 4;
    
              (p1
    `1 ) 
    <= (p10 
    `1 ) by 
    A14,
    A15,
    EUCLID: 52;
    
              then
    0  
    = (p1 
    `1 ) by 
    A14,
    A16,
    A88,
    Lm4,
    TOPREAL1: 3;
    
              hence contradiction by
    A14,
    A17,
    A87,
    EUCLID: 53;
    
            end;
    
            then
    
            
    
    A89: 
    {p00}
    <> (L1 
    /\ ( 
    LSeg (p1,p10))) by 
    ZFMISC_1: 31;
    
            (L1
    /\ ( 
    LSeg (p1,p10))) 
    c=  
    {p00} by
    A3,
    Lm24,
    TOPREAL1: 6,
    TOPREAL1: 17,
    XBOOLE_1: 26;
    
            then
    
            
    
    A90: (L1 
    /\ ( 
    LSeg (p1,p10))) 
    =  
    {} by 
    A89,
    ZFMISC_1: 33;
    
            now
    
              assume p10
    in (( 
    LSeg (p1,p00)) 
    /\ L4); 
    
              then
    
              
    
    A91: p10 
    in ( 
    LSeg (p00,p1)) by 
    XBOOLE_0:def 4;
    
              (p00
    `1 ) 
    <= (p1 
    `1 ) by 
    A14,
    A16,
    EUCLID: 52;
    
              then (p10
    `1 ) 
    <= (p1 
    `1 ) by 
    A91,
    TOPREAL1: 3;
    
              then 1
    = (p1 
    `1 ) by 
    A14,
    A15,
    Lm8,
    XXREAL_0: 1;
    
              hence contradiction by
    A14,
    A17,
    A87,
    EUCLID: 53;
    
            end;
    
            then
    
            
    
    A92: 
    {p10}
    <> (( 
    LSeg (p1,p00)) 
    /\ L4) by 
    ZFMISC_1: 31;
    
            ((
    LSeg (p1,p00)) 
    /\ L4) 
    c=  
    {p10} by
    A3,
    Lm21,
    TOPREAL1: 6,
    TOPREAL1: 16,
    XBOOLE_1: 26;
    
            then ((
    LSeg (p1,p00)) 
    /\ L4) 
    =  
    {} by 
    A92,
    ZFMISC_1: 33;
    
            hence (P1
    /\ P2) 
    = (( 
    {p1}
    \/ (L1 
    /\ ( 
    LSeg (p11,p2)))) 
    \/ ((( 
    LSeg (p01,p2)) 
    /\ L4) 
    \/  
    {p2})) by
    A83,
    A90;
    
          end;
    
        end;
    
        now
    
          per cases ;
    
            suppose
    
            
    
    A93: p2 
    = p01; 
    
            then ((
    LSeg (p01,p2)) 
    /\ L4) 
    = ( 
    {p01}
    /\ L4) by 
    RLTOPSP1: 70;
    
            then ((
    LSeg (p01,p2)) 
    /\ L4) 
    =  
    {} by 
    Lm1,
    Lm15;
    
            
    
            hence (P1
    /\ P2) 
    = ( 
    {p1}
    \/ ( 
    {p2}
    \/  
    {p2})) by
    A84,
    A93,
    TOPREAL1: 15,
    XBOOLE_1: 4
    
            .=
    {p1, p2} by
    ENUMSET1: 1;
    
          end;
    
            suppose
    
            
    
    A94: p2 
    = p11; 
    
            then (L1
    /\ ( 
    LSeg (p11,p2))) 
    = (L1 
    /\  
    {p11}) by
    RLTOPSP1: 70;
    
            then (L1
    /\ ( 
    LSeg (p11,p2))) 
    =  
    {} by 
    Lm1,
    Lm18;
    
            hence thesis by
    A84,
    A94,
    ENUMSET1: 1,
    TOPREAL1: 18;
    
          end;
    
            suppose
    
            
    
    A95: p2 
    <> p11 & p2 
    <> p01; 
    
            now
    
              assume p11
    in (( 
    LSeg (p01,p2)) 
    /\ L4); 
    
              then
    
              
    
    A96: p11 
    in ( 
    LSeg (p01,p2)) by 
    XBOOLE_0:def 4;
    
              (p01
    `1 ) 
    <= (p2 
    `1 ) by 
    A79,
    EUCLID: 52;
    
              then (p11
    `1 ) 
    <= (p2 
    `1 ) by 
    A96,
    TOPREAL1: 3;
    
              then 1
    = (p2 
    `1 ) by 
    A79,
    Lm10,
    XXREAL_0: 1;
    
              hence contradiction by
    A79,
    A95,
    EUCLID: 53;
    
            end;
    
            then
    
            
    
    A97: 
    {p11}
    <> (( 
    LSeg (p01,p2)) 
    /\ L4) by 
    ZFMISC_1: 31;
    
            ((
    LSeg (p01,p2)) 
    /\ L4) 
    c=  
    {p11} by
    A70,
    Lm23,
    TOPREAL1: 6,
    TOPREAL1: 18,
    XBOOLE_1: 26;
    
            then
    
            
    
    A98: (( 
    LSeg (p01,p2)) 
    /\ L4) 
    =  
    {} by 
    A97,
    ZFMISC_1: 33;
    
            now
    
              assume p01
    in (L1 
    /\ ( 
    LSeg (p11,p2))); 
    
              then
    
              
    
    A99: p01 
    in ( 
    LSeg (p2,p11)) by 
    XBOOLE_0:def 4;
    
              (p2
    `1 ) 
    <= (p11 
    `1 ) by 
    A79,
    EUCLID: 52;
    
              then (p2
    `1 ) 
    =  
    0 by 
    A79,
    A99,
    Lm6,
    TOPREAL1: 3;
    
              hence contradiction by
    A79,
    A95,
    EUCLID: 53;
    
            end;
    
            then
    
            
    
    A100: 
    {p01}
    <> (L1 
    /\ ( 
    LSeg (p11,p2))) by 
    ZFMISC_1: 31;
    
            (L1
    /\ ( 
    LSeg (p11,p2))) 
    c=  
    {p01} by
    A70,
    Lm26,
    TOPREAL1: 6,
    TOPREAL1: 15,
    XBOOLE_1: 26;
    
            then (L1
    /\ ( 
    LSeg (p11,p2))) 
    =  
    {} by 
    A100,
    ZFMISC_1: 33;
    
            hence thesis by
    A84,
    A98,
    ENUMSET1: 1;
    
          end;
    
        end;
    
        hence thesis;
    
      end;
    
        suppose
    
        
    
    A101: p2 
    in L3; 
    
        
    
        
    
    A102: p 
    =  
    |[(p
    `1 ), (p 
    `2 )]| by 
    EUCLID: 53;
    
        
    
        
    
    A103: ( 
    LSeg (p1,p2)) 
    c= L3 by 
    A3,
    A101,
    TOPREAL1: 6;
    
        consider q such that
    
        
    
    A104: q 
    = p2 and 
    
        
    
    A105: (q 
    `1 ) 
    <= 1 and 
    
        
    
    A106: (q 
    `1 ) 
    >=  
    0 and 
    
        
    
    A107: (q 
    `2 ) 
    =  
    0 by 
    A101,
    TOPREAL1: 13;
    
        
    
        
    
    A108: q 
    =  
    |[(q
    `1 ), (q 
    `2 )]| by 
    EUCLID: 53;
    
        now
    
          per cases by
    A1,
    A14,
    A17,
    A104,
    A107,
    A102,
    A108,
    XXREAL_0: 1;
    
            suppose
    
            
    
    A109: (p 
    `1 ) 
    < (q 
    `1 ); 
    
            now
    
              assume p10
    in (( 
    LSeg (p1,p00)) 
    /\ L4); 
    
              then
    
              
    
    A110: p10 
    in ( 
    LSeg (p00,p1)) by 
    XBOOLE_0:def 4;
    
              (p00
    `1 ) 
    <= (p1 
    `1 ) by 
    A14,
    A16,
    EUCLID: 52;
    
              then (p10
    `1 ) 
    <= (p1 
    `1 ) by 
    A110,
    TOPREAL1: 3;
    
              hence contradiction by
    A14,
    A15,
    A105,
    A109,
    Lm8,
    XXREAL_0: 1;
    
            end;
    
            then
    
            
    
    A111: 
    {p10}
    <> (( 
    LSeg (p1,p00)) 
    /\ L4) by 
    ZFMISC_1: 31;
    
            ((
    LSeg (p1,p00)) 
    /\ L4) 
    c=  
    {p10} by
    A3,
    Lm21,
    TOPREAL1: 6,
    TOPREAL1: 16,
    XBOOLE_1: 26;
    
            then
    
            
    
    A112: (( 
    LSeg (p1,p00)) 
    /\ L4) 
    =  
    {} by 
    A111,
    ZFMISC_1: 33;
    
            p00
    in ( 
    LSeg (p1,p00)) by 
    RLTOPSP1: 68;
    
            then
    
            
    
    A113: (( 
    LSeg (p1,p00)) 
    /\ L1) 
    <>  
    {} by 
    Lm20,
    XBOOLE_0:def 4;
    
            now
    
              assume p00
    in (L1 
    /\ ( 
    LSeg (p10,p2))); 
    
              then
    
              
    
    A114: p00 
    in ( 
    LSeg (p2,p10)) by 
    XBOOLE_0:def 4;
    
              (p2
    `1 ) 
    <= (p10 
    `1 ) by 
    A104,
    A105,
    EUCLID: 52;
    
              hence contradiction by
    A16,
    A104,
    A109,
    A114,
    Lm4,
    TOPREAL1: 3;
    
            end;
    
            then
    
            
    
    A115: 
    {p00}
    <> (L1 
    /\ ( 
    LSeg (p10,p2))) by 
    ZFMISC_1: 31;
    
            (L1
    /\ ( 
    LSeg (p10,p2))) 
    c=  
    {p00} by
    A101,
    Lm24,
    TOPREAL1: 6,
    TOPREAL1: 17,
    XBOOLE_1: 26;
    
            then
    
            
    
    A116: (L1 
    /\ ( 
    LSeg (p10,p2))) 
    =  
    {} by 
    A115,
    ZFMISC_1: 33;
    
            (L3
    /\ L2) 
    =  
    {} by 
    TOPREAL1: 19,
    XBOOLE_0:def 7;
    
            then
    
            
    
    A117: (( 
    LSeg (p1,p2)) 
    /\ L2) 
    =  
    {} by 
    A103,
    XBOOLE_1: 3,
    XBOOLE_1: 26;
    
            
    
            
    
    A118: (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p1,p00))) 
    c=  
    {p1}
    
            proof
    
              let a be
    object;
    
              assume
    
              
    
    A119: a 
    in (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p1,p00))); 
    
              then
    
              reconsider p = a as
    Point of ( 
    TOP-REAL 2); 
    
              
    
              
    
    A120: p 
    in ( 
    LSeg (p00,p1)) by 
    A119,
    XBOOLE_0:def 4;
    
              (p00
    `1 ) 
    <= (p1 
    `1 ) by 
    A14,
    A16,
    EUCLID: 52;
    
              then
    
              
    
    A121: (p 
    `1 ) 
    <= (p1 
    `1 ) by 
    A120,
    TOPREAL1: 3;
    
              
    
              
    
    A122: p 
    in ( 
    LSeg (p1,p2)) by 
    A119,
    XBOOLE_0:def 4;
    
              then (p1
    `1 ) 
    <= (p 
    `1 ) by 
    A14,
    A104,
    A109,
    TOPREAL1: 3;
    
              then
    
              
    
    A123: (p1 
    `1 ) 
    = (p 
    `1 ) by 
    A121,
    XXREAL_0: 1;
    
              (p1
    `2 ) 
    <= (p 
    `2 ) by 
    A14,
    A17,
    A104,
    A107,
    A122,
    TOPREAL1: 4;
    
              then (p
    `2 ) 
    =  
    0 by 
    A14,
    A17,
    A104,
    A107,
    A122,
    TOPREAL1: 4;
    
              
    
              then p
    =  
    |[(p1
    `1 ), 
    0 ]| by 
    A123,
    EUCLID: 53
    
              .= p1 by
    A14,
    A17,
    EUCLID: 53;
    
              hence thesis by
    TARSKI:def 1;
    
            end;
    
            
    
            
    
    A124: (( 
    LSeg (p1,p00)) 
    /\ L1) 
    c= (L3 
    /\ L1) by 
    A3,
    Lm21,
    TOPREAL1: 6,
    XBOOLE_1: 26;
    
            take P1 = (
    LSeg (p1,p2)), P2 = (( 
    LSeg (p1,p00)) 
    \/ (((L1 
    \/ L2) 
    \/ L4) 
    \/ ( 
    LSeg (p10,p2)))); 
    
            
    
            
    
    A125: (L3 
    /\ L2) 
    =  
    {} by 
    TOPREAL1: 19,
    XBOOLE_0:def 7;
    
            (L2
    /\ ( 
    LSeg (p10,p2))) 
    c= (L2 
    /\ L3) by 
    A101,
    Lm24,
    TOPREAL1: 6,
    XBOOLE_1: 26;
    
            then
    
            
    
    A126: (L2 
    /\ ( 
    LSeg (p10,p2))) 
    =  
    {} by 
    A125,
    XBOOLE_1: 3;
    
            thus P1
    is_an_arc_of (p1,p2) by 
    A1,
    TOPREAL1: 9;
    
            
    
            
    
    A127: ((L1 
    \/ L2) 
    /\ L4) 
    = ((L1 
    /\ L4) 
    \/ (L2 
    /\ L4)) by 
    XBOOLE_1: 23
    
            .=
    {p11} by
    Lm3,
    TOPREAL1: 18;
    
            
    
            
    
    A128: (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p10,p2))) 
    c=  
    {p2}
    
            proof
    
              let a be
    object;
    
              assume
    
              
    
    A129: a 
    in (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p10,p2))); 
    
              then
    
              reconsider p = a as
    Point of ( 
    TOP-REAL 2); 
    
              
    
              
    
    A130: p 
    in ( 
    LSeg (p2,p10)) by 
    A129,
    XBOOLE_0:def 4;
    
              (p2
    `1 ) 
    <= (p10 
    `1 ) by 
    A104,
    A105,
    EUCLID: 52;
    
              then
    
              
    
    A131: (p2 
    `1 ) 
    <= (p 
    `1 ) by 
    A130,
    TOPREAL1: 3;
    
              
    
              
    
    A132: p 
    in ( 
    LSeg (p1,p2)) by 
    A129,
    XBOOLE_0:def 4;
    
              then (p
    `1 ) 
    <= (p2 
    `1 ) by 
    A14,
    A104,
    A109,
    TOPREAL1: 3;
    
              then
    
              
    
    A133: (p2 
    `1 ) 
    = (p 
    `1 ) by 
    A131,
    XXREAL_0: 1;
    
              (p1
    `2 ) 
    <= (p 
    `2 ) by 
    A14,
    A17,
    A104,
    A107,
    A132,
    TOPREAL1: 4;
    
              then (p
    `2 ) 
    =  
    0 by 
    A14,
    A17,
    A104,
    A107,
    A132,
    TOPREAL1: 4;
    
              
    
              then p
    =  
    |[(p2
    `1 ), 
    0 ]| by 
    A133,
    EUCLID: 53
    
              .= p2 by
    A104,
    A107,
    EUCLID: 53;
    
              hence thesis by
    TARSKI:def 1;
    
            end;
    
            (L3
    /\ L2) 
    =  
    {} by 
    TOPREAL1: 19,
    XBOOLE_0:def 7;
    
            then
    
            
    
    A134: (( 
    LSeg (p1,p00)) 
    /\ L2) 
    =  
    {} by 
    A10,
    XBOOLE_1: 3,
    XBOOLE_1: 26;
    
            
    
    A135: 
    
            now
    
              set a = the
    Element of (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p10,p2))); 
    
              assume
    
              
    
    A136: (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p10,p2))) 
    <>  
    {} ; 
    
              then
    
              reconsider p = a as
    Point of ( 
    TOP-REAL 2) by 
    TARSKI:def 3;
    
              
    
              
    
    A137: p 
    in ( 
    LSeg (p00,p1)) by 
    A136,
    XBOOLE_0:def 4;
    
              
    
              
    
    A138: p 
    in ( 
    LSeg (p2,p10)) by 
    A136,
    XBOOLE_0:def 4;
    
              (p2
    `1 ) 
    <= (p10 
    `1 ) by 
    A104,
    A105,
    EUCLID: 52;
    
              then
    
              
    
    A139: (p2 
    `1 ) 
    <= (p 
    `1 ) by 
    A138,
    TOPREAL1: 3;
    
              (p00
    `1 ) 
    <= (p1 
    `1 ) by 
    A14,
    A16,
    EUCLID: 52;
    
              then (p
    `1 ) 
    <= (p1 
    `1 ) by 
    A137,
    TOPREAL1: 3;
    
              hence contradiction by
    A14,
    A104,
    A109,
    A139,
    XXREAL_0: 2;
    
            end;
    
            p10
    in ( 
    LSeg (p10,p2)) by 
    RLTOPSP1: 68;
    
            then
    
            
    
    A140: (L4 
    /\ ( 
    LSeg (p10,p2))) 
    <>  
    {} by 
    Lm25,
    XBOOLE_0:def 4;
    
            (L4
    /\ ( 
    LSeg (p10,p2))) 
    c= (L4 
    /\ L3) by 
    A101,
    Lm24,
    TOPREAL1: 6,
    XBOOLE_1: 26;
    
            then
    
            
    
    A141: (L4 
    /\ ( 
    LSeg (p10,p2))) 
    =  
    {p10} by
    A140,
    TOPREAL1: 16,
    ZFMISC_1: 33;
    
            (L1
    \/ L2) 
    is_an_arc_of (p00,p11) by 
    Lm5,
    Lm7,
    TOPREAL1: 9,
    TOPREAL1: 10,
    TOPREAL1: 15;
    
            then
    
            
    
    A142: ((L1 
    \/ L2) 
    \/ L4) 
    is_an_arc_of (p00,p10) by 
    A127,
    TOPREAL1: 10;
    
            (((L1
    \/ L2) 
    \/ L4) 
    /\ ( 
    LSeg (p10,p2))) 
    = (((L1 
    \/ L2) 
    /\ ( 
    LSeg (p10,p2))) 
    \/ (L4 
    /\ ( 
    LSeg (p10,p2)))) by 
    XBOOLE_1: 23
    
            .= (((L1
    /\ ( 
    LSeg (p10,p2))) 
    \/ (L2 
    /\ ( 
    LSeg (p10,p2)))) 
    \/  
    {p10}) by
    A141,
    XBOOLE_1: 23
    
            .=
    {p10} by
    A116,
    A126;
    
            then
    
            
    
    A143: (((L1 
    \/ L2) 
    \/ L4) 
    \/ ( 
    LSeg (p10,p2))) 
    is_an_arc_of (p00,p2) by 
    A142,
    TOPREAL1: 10;
    
            ((
    LSeg (p1,p00)) 
    /\ (((L1 
    \/ L2) 
    \/ L4) 
    \/ ( 
    LSeg (p10,p2)))) 
    = ((( 
    LSeg (p1,p00)) 
    /\ ((L1 
    \/ L2) 
    \/ L4)) 
    \/ (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p10,p2)))) by 
    XBOOLE_1: 23
    
            .= (((
    LSeg (p1,p00)) 
    /\ (L1 
    \/ L2)) 
    \/ (( 
    LSeg (p1,p00)) 
    /\ L4)) by 
    A135,
    XBOOLE_1: 23
    
            .= (((
    LSeg (p1,p00)) 
    /\ L1) 
    \/ (( 
    LSeg (p1,p00)) 
    /\ L2)) by 
    A112,
    XBOOLE_1: 23
    
            .=
    {p00} by
    A134,
    A124,
    A113,
    TOPREAL1: 17,
    ZFMISC_1: 33;
    
            hence P2
    is_an_arc_of (p1,p2) by 
    A143,
    TOPREAL1: 11;
    
            
    
            
    
    A144: p1 
    in ( 
    LSeg (p1,p00)) by 
    RLTOPSP1: 68;
    
            p1
    in ( 
    LSeg (p1,p2)) by 
    RLTOPSP1: 68;
    
            then p1
    in (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p1,p00))) by 
    A144,
    XBOOLE_0:def 4;
    
            then
    {p1}
    c= (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p1,p00))) by 
    ZFMISC_1: 31;
    
            then
    
            
    
    A145: (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p1,p00))) 
    =  
    {p1} by
    A118,
    XBOOLE_0:def 10;
    
            
    
            thus (P1
    \/ P2) 
    = ((( 
    LSeg (p00,p1)) 
    \/ ( 
    LSeg (p1,p2))) 
    \/ (((L1 
    \/ L2) 
    \/ L4) 
    \/ ( 
    LSeg (p10,p2)))) by 
    XBOOLE_1: 4
    
            .= ((((
    LSeg (p00,p1)) 
    \/ ( 
    LSeg (p1,p2))) 
    \/ ( 
    LSeg (p2,p10))) 
    \/ ((L1 
    \/ L2) 
    \/ L4)) by 
    XBOOLE_1: 4
    
            .= (((L1
    \/ L2) 
    \/ L4) 
    \/ L3) by 
    A3,
    A101,
    TOPREAL1: 7
    
            .=
    R^2-unit_square by 
    TOPREAL1:def 2,
    XBOOLE_1: 4;
    
            
    
            
    
    A146: p2 
    in ( 
    LSeg (p10,p2)) by 
    RLTOPSP1: 68;
    
            p2
    in ( 
    LSeg (p1,p2)) by 
    RLTOPSP1: 68;
    
            then p2
    in (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p10,p2))) by 
    A146,
    XBOOLE_0:def 4;
    
            then
    {p2}
    c= (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p10,p2))) by 
    ZFMISC_1: 31;
    
            then
    
            
    
    A147: (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p10,p2))) 
    =  
    {p2} by
    A128,
    XBOOLE_0:def 10;
    
            
    
            
    
    A148: (P1 
    /\ P2) 
    = ((( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p1,p00))) 
    \/ (( 
    LSeg (p1,p2)) 
    /\ (((L1 
    \/ L2) 
    \/ L4) 
    \/ ( 
    LSeg (p10,p2))))) by 
    XBOOLE_1: 23
    
            .= (
    {p1}
    \/ ((( 
    LSeg (p1,p2)) 
    /\ ((L1 
    \/ L2) 
    \/ L4)) 
    \/  
    {p2})) by
    A145,
    A147,
    XBOOLE_1: 23
    
            .= (
    {p1}
    \/ (((( 
    LSeg (p1,p2)) 
    /\ (L1 
    \/ L2)) 
    \/ (( 
    LSeg (p1,p2)) 
    /\ L4)) 
    \/  
    {p2})) by
    XBOOLE_1: 23
    
            .= (
    {p1}
    \/ ((((( 
    LSeg (p1,p2)) 
    /\ L1) 
    \/ (( 
    LSeg (p1,p2)) 
    /\ L2)) 
    \/ (( 
    LSeg (p1,p2)) 
    /\ L4)) 
    \/  
    {p2})) by
    XBOOLE_1: 23
    
            .= (
    {p1}
    \/ ((( 
    LSeg (p1,p2)) 
    /\ L1) 
    \/ ((( 
    LSeg (p1,p2)) 
    /\ L4) 
    \/  
    {p2}))) by
    A117,
    XBOOLE_1: 4
    
            .= ((
    {p1}
    \/ (( 
    LSeg (p1,p2)) 
    /\ L1)) 
    \/ ((( 
    LSeg (p1,p2)) 
    /\ L4) 
    \/  
    {p2})) by
    XBOOLE_1: 4;
    
            
    
    A149: 
    
            now
    
              per cases ;
    
                suppose
    
                
    
    A150: p1 
    = p00; 
    
                p1
    in ( 
    LSeg (p1,p2)) by 
    RLTOPSP1: 68;
    
                then
    
                
    
    A151: (( 
    LSeg (p1,p2)) 
    /\ L1) 
    <>  
    {} by 
    A150,
    Lm20,
    XBOOLE_0:def 4;
    
                ((
    LSeg (p1,p2)) 
    /\ L1) 
    c= (L3 
    /\ L1) by 
    A3,
    A101,
    TOPREAL1: 6,
    XBOOLE_1: 26;
    
                then ((
    LSeg (p1,p2)) 
    /\ L1) 
    =  
    {p1} by
    A150,
    A151,
    TOPREAL1: 17,
    ZFMISC_1: 33;
    
                hence (P1
    /\ P2) 
    = ( 
    {p1}
    \/ ((( 
    LSeg (p1,p2)) 
    /\ L4) 
    \/  
    {p2})) by
    A148;
    
              end;
    
                suppose
    
                
    
    A152: p1 
    <> p00; 
    
                now
    
                  assume p00
    in (( 
    LSeg (p1,p2)) 
    /\ L1); 
    
                  then p00
    in ( 
    LSeg (p1,p2)) by 
    XBOOLE_0:def 4;
    
                  then (p1
    `1 ) 
    =  
    0 by 
    A14,
    A16,
    A104,
    A109,
    Lm4,
    TOPREAL1: 3;
    
                  hence contradiction by
    A14,
    A17,
    A152,
    EUCLID: 53;
    
                end;
    
                then
    
                
    
    A153: 
    {p00}
    <> (( 
    LSeg (p1,p2)) 
    /\ L1) by 
    ZFMISC_1: 31;
    
                ((
    LSeg (p1,p2)) 
    /\ L1) 
    c= (L3 
    /\ L1) by 
    A3,
    A101,
    TOPREAL1: 6,
    XBOOLE_1: 26;
    
                then ((
    LSeg (p1,p2)) 
    /\ L1) 
    =  
    {} by 
    A153,
    TOPREAL1: 17,
    ZFMISC_1: 33;
    
                hence (P1
    /\ P2) 
    = ( 
    {p1}
    \/ ((( 
    LSeg (p1,p2)) 
    /\ L4) 
    \/  
    {p2})) by
    A148;
    
              end;
    
            end;
    
            now
    
              per cases ;
    
                suppose
    
                
    
    A154: p2 
    = p10; 
    
                p2
    in ( 
    LSeg (p1,p2)) by 
    RLTOPSP1: 68;
    
                then
    
                
    
    A155: (( 
    LSeg (p1,p2)) 
    /\ L4) 
    <>  
    {} by 
    A154,
    Lm25,
    XBOOLE_0:def 4;
    
                ((
    LSeg (p1,p2)) 
    /\ L4) 
    c=  
    {p2} by
    A3,
    A101,
    A154,
    TOPREAL1: 6,
    TOPREAL1: 16,
    XBOOLE_1: 26;
    
                then ((
    LSeg (p1,p2)) 
    /\ L4) 
    =  
    {p2} by
    A155,
    ZFMISC_1: 33;
    
                hence (P1
    /\ P2) 
    =  
    {p1, p2} by
    A149,
    ENUMSET1: 1;
    
              end;
    
                suppose
    
                
    
    A156: p2 
    <> p10; 
    
                now
    
                  assume p10
    in (( 
    LSeg (p1,p2)) 
    /\ L4); 
    
                  then p10
    in ( 
    LSeg (p1,p2)) by 
    XBOOLE_0:def 4;
    
                  then (p10
    `1 ) 
    <= (p2 
    `1 ) by 
    A14,
    A104,
    A109,
    TOPREAL1: 3;
    
                  then (p2
    `1 ) 
    = 1 by 
    A104,
    A105,
    Lm8,
    XXREAL_0: 1;
    
                  hence contradiction by
    A104,
    A107,
    A156,
    EUCLID: 53;
    
                end;
    
                then
    
                
    
    A157: 
    {p10}
    <> (( 
    LSeg (p1,p2)) 
    /\ L4) by 
    ZFMISC_1: 31;
    
                ((
    LSeg (p1,p2)) 
    /\ L4) 
    c=  
    {p10} by
    A3,
    A101,
    TOPREAL1: 6,
    TOPREAL1: 16,
    XBOOLE_1: 26;
    
                then ((
    LSeg (p1,p2)) 
    /\ L4) 
    =  
    {} by 
    A157,
    ZFMISC_1: 33;
    
                hence (P1
    /\ P2) 
    =  
    {p1, p2} by
    A149,
    ENUMSET1: 1;
    
              end;
    
            end;
    
            hence (P1
    /\ P2) 
    =  
    {p1, p2};
    
          end;
    
            suppose
    
            
    
    A158: (q 
    `1 ) 
    < (p 
    `1 ); 
    
            
    
            
    
    A159: (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p00,p2))) 
    c=  
    {p2}
    
            proof
    
              let a be
    object;
    
              assume
    
              
    
    A160: a 
    in (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p00,p2))); 
    
              then
    
              reconsider p = a as
    Point of ( 
    TOP-REAL 2); 
    
              
    
              
    
    A161: p 
    in ( 
    LSeg (p00,p2)) by 
    A160,
    XBOOLE_0:def 4;
    
              (p00
    `1 ) 
    <= (p2 
    `1 ) by 
    A104,
    A106,
    EUCLID: 52;
    
              then
    
              
    
    A162: (p 
    `1 ) 
    <= (p2 
    `1 ) by 
    A161,
    TOPREAL1: 3;
    
              
    
              
    
    A163: p 
    in ( 
    LSeg (p2,p1)) by 
    A160,
    XBOOLE_0:def 4;
    
              then (p2
    `1 ) 
    <= (p 
    `1 ) by 
    A14,
    A104,
    A158,
    TOPREAL1: 3;
    
              then
    
              
    
    A164: (p2 
    `1 ) 
    = (p 
    `1 ) by 
    A162,
    XXREAL_0: 1;
    
              (p2
    `2 ) 
    <= (p 
    `2 ) by 
    A14,
    A17,
    A104,
    A107,
    A163,
    TOPREAL1: 4;
    
              then (p
    `2 ) 
    =  
    0 by 
    A14,
    A17,
    A104,
    A107,
    A163,
    TOPREAL1: 4;
    
              
    
              then p
    =  
    |[(p2
    `1 ), 
    0 ]| by 
    A164,
    EUCLID: 53
    
              .= p2 by
    A104,
    A107,
    EUCLID: 53;
    
              hence thesis by
    TARSKI:def 1;
    
            end;
    
            p10
    in ( 
    LSeg (p1,p10)) by 
    RLTOPSP1: 68;
    
            then
    
            
    
    A165: (( 
    LSeg (p1,p10)) 
    /\ L4) 
    <>  
    {} by 
    Lm25,
    XBOOLE_0:def 4;
    
            now
    
              assume p10
    in (L4 
    /\ ( 
    LSeg (p00,p2))); 
    
              then
    
              
    
    A166: p10 
    in ( 
    LSeg (p00,p2)) by 
    XBOOLE_0:def 4;
    
              (p00
    `1 ) 
    <= (p2 
    `1 ) by 
    A104,
    A106,
    EUCLID: 52;
    
              then (p10
    `1 ) 
    <= (p2 
    `1 ) by 
    A166,
    TOPREAL1: 3;
    
              hence contradiction by
    A15,
    A104,
    A105,
    A158,
    Lm8,
    XXREAL_0: 1;
    
            end;
    
            then
    
            
    
    A167: 
    {p10}
    <> (L4 
    /\ ( 
    LSeg (p00,p2))) by 
    ZFMISC_1: 31;
    
            (L4
    /\ ( 
    LSeg (p00,p2))) 
    c= (L4 
    /\ L3) by 
    A101,
    Lm21,
    TOPREAL1: 6,
    XBOOLE_1: 26;
    
            then
    
            
    
    A168: (L4 
    /\ ( 
    LSeg (p00,p2))) 
    =  
    {} by 
    A167,
    TOPREAL1: 16,
    ZFMISC_1: 33;
    
            
    
            
    
    A169: ((L4 
    \/ L2) 
    /\ L1) 
    = ((L1 
    /\ L4) 
    \/ (L2 
    /\ L1)) by 
    XBOOLE_1: 23
    
            .=
    {p01} by
    Lm3,
    TOPREAL1: 15;
    
            (L4
    \/ L2) 
    is_an_arc_of (p10,p01) by 
    Lm9,
    Lm11,
    TOPREAL1: 9,
    TOPREAL1: 10,
    TOPREAL1: 18;
    
            then
    
            
    
    A170: ((L4 
    \/ L2) 
    \/ L1) 
    is_an_arc_of (p10,p00) by 
    A169,
    TOPREAL1: 10;
    
            now
    
              assume p00
    in (( 
    LSeg (p1,p10)) 
    /\ L1); 
    
              then
    
              
    
    A171: p00 
    in ( 
    LSeg (p1,p10)) by 
    XBOOLE_0:def 4;
    
              (p1
    `1 ) 
    <= (p10 
    `1 ) by 
    A14,
    A15,
    EUCLID: 52;
    
              hence contradiction by
    A14,
    A106,
    A158,
    A171,
    Lm4,
    TOPREAL1: 3;
    
            end;
    
            then
    
            
    
    A172: 
    {p00}
    <> (( 
    LSeg (p1,p10)) 
    /\ L1) by 
    ZFMISC_1: 31;
    
            ((
    LSeg (p1,p10)) 
    /\ L1) 
    c= (L3 
    /\ L1) by 
    A3,
    Lm24,
    TOPREAL1: 6,
    XBOOLE_1: 26;
    
            then
    
            
    
    A173: (( 
    LSeg (p1,p10)) 
    /\ L1) 
    =  
    {} by 
    A172,
    TOPREAL1: 17,
    ZFMISC_1: 33;
    
            p00
    in ( 
    LSeg (p00,p2)) by 
    RLTOPSP1: 68;
    
            then
    
            
    
    A174: (L1 
    /\ ( 
    LSeg (p00,p2))) 
    <>  
    {} by 
    Lm20,
    XBOOLE_0:def 4;
    
            (L1
    /\ ( 
    LSeg (p00,p2))) 
    c=  
    {p00} by
    A101,
    Lm21,
    TOPREAL1: 6,
    TOPREAL1: 17,
    XBOOLE_1: 26;
    
            then
    
            
    
    A175: (L1 
    /\ ( 
    LSeg (p00,p2))) 
    =  
    {p00} by
    A174,
    ZFMISC_1: 33;
    
            
    
            
    
    A176: (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p1,p10))) 
    c=  
    {p1}
    
            proof
    
              let a be
    object;
    
              assume
    
              
    
    A177: a 
    in (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p1,p10))); 
    
              then
    
              reconsider p = a as
    Point of ( 
    TOP-REAL 2); 
    
              
    
              
    
    A178: p 
    in ( 
    LSeg (p1,p10)) by 
    A177,
    XBOOLE_0:def 4;
    
              (p1
    `1 ) 
    <= (p10 
    `1 ) by 
    A14,
    A15,
    EUCLID: 52;
    
              then
    
              
    
    A179: (p1 
    `1 ) 
    <= (p 
    `1 ) by 
    A178,
    TOPREAL1: 3;
    
              
    
              
    
    A180: p 
    in ( 
    LSeg (p2,p1)) by 
    A177,
    XBOOLE_0:def 4;
    
              then (p
    `1 ) 
    <= (p1 
    `1 ) by 
    A14,
    A104,
    A158,
    TOPREAL1: 3;
    
              then
    
              
    
    A181: (p1 
    `1 ) 
    = (p 
    `1 ) by 
    A179,
    XXREAL_0: 1;
    
              (p2
    `2 ) 
    <= (p 
    `2 ) by 
    A14,
    A17,
    A104,
    A107,
    A180,
    TOPREAL1: 4;
    
              then (p
    `2 ) 
    =  
    0 by 
    A14,
    A17,
    A104,
    A107,
    A180,
    TOPREAL1: 4;
    
              
    
              then p
    =  
    |[(p1
    `1 ), 
    0 ]| by 
    A181,
    EUCLID: 53
    
              .= p1 by
    A14,
    A17,
    EUCLID: 53;
    
              hence thesis by
    TARSKI:def 1;
    
            end;
    
            (L3
    /\ L2) 
    =  
    {} by 
    TOPREAL1: 19,
    XBOOLE_0:def 7;
    
            then
    
            
    
    A182: (( 
    LSeg (p1,p10)) 
    /\ L2) 
    =  
    {} by 
    A12,
    XBOOLE_1: 3,
    XBOOLE_1: 26;
    
            
    
    A183: 
    
            now
    
              set a = the
    Element of (( 
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p00,p2))); 
    
              assume
    
              
    
    A184: (( 
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p00,p2))) 
    <>  
    {} ; 
    
              then
    
              reconsider p = a as
    Point of ( 
    TOP-REAL 2) by 
    TARSKI:def 3;
    
              
    
              
    
    A185: p 
    in ( 
    LSeg (p1,p10)) by 
    A184,
    XBOOLE_0:def 4;
    
              
    
              
    
    A186: p 
    in ( 
    LSeg (p00,p2)) by 
    A184,
    XBOOLE_0:def 4;
    
              (p00
    `1 ) 
    <= (p2 
    `1 ) by 
    A104,
    A106,
    EUCLID: 52;
    
              then
    
              
    
    A187: (p 
    `1 ) 
    <= (p2 
    `1 ) by 
    A186,
    TOPREAL1: 3;
    
              (p1
    `1 ) 
    <= (p10 
    `1 ) by 
    A14,
    A15,
    EUCLID: 52;
    
              then (p1
    `1 ) 
    <= (p 
    `1 ) by 
    A185,
    TOPREAL1: 3;
    
              hence contradiction by
    A14,
    A104,
    A158,
    A187,
    XXREAL_0: 2;
    
            end;
    
            take P1 = (
    LSeg (p1,p2)), P2 = (( 
    LSeg (p1,p10)) 
    \/ (((L4 
    \/ L2) 
    \/ L1) 
    \/ ( 
    LSeg (p00,p2)))); 
    
            
    
            
    
    A188: (L3 
    /\ L2) 
    =  
    {} by 
    TOPREAL1: 19,
    XBOOLE_0:def 7;
    
            (L2
    /\ ( 
    LSeg (p00,p2))) 
    c= (L2 
    /\ L3) by 
    A101,
    Lm21,
    TOPREAL1: 6,
    XBOOLE_1: 26;
    
            then
    
            
    
    A189: (L2 
    /\ ( 
    LSeg (p00,p2))) 
    =  
    {} by 
    A188,
    XBOOLE_1: 3;
    
            
    
            
    
    A190: (( 
    LSeg (p1,p10)) 
    /\ L4) 
    c=  
    {p10} by
    A3,
    Lm24,
    TOPREAL1: 6,
    TOPREAL1: 16,
    XBOOLE_1: 26;
    
            (((L4
    \/ L2) 
    \/ L1) 
    /\ ( 
    LSeg (p00,p2))) 
    = (((L4 
    \/ L2) 
    /\ ( 
    LSeg (p00,p2))) 
    \/ (L1 
    /\ ( 
    LSeg (p00,p2)))) by 
    XBOOLE_1: 23
    
            .= (((L4
    /\ ( 
    LSeg (p00,p2))) 
    \/ (L2 
    /\ ( 
    LSeg (p00,p2)))) 
    \/  
    {p00}) by
    A175,
    XBOOLE_1: 23
    
            .=
    {p00} by
    A168,
    A189;
    
            then
    
            
    
    A191: (((L4 
    \/ L2) 
    \/ L1) 
    \/ ( 
    LSeg (p00,p2))) 
    is_an_arc_of (p10,p2) by 
    A170,
    TOPREAL1: 10;
    
            thus P1
    is_an_arc_of (p1,p2) by 
    A1,
    TOPREAL1: 9;
    
            
    
            
    
    A192: p2 
    in ( 
    LSeg (p00,p2)) by 
    RLTOPSP1: 68;
    
            ((
    LSeg (p1,p10)) 
    /\ (((L4 
    \/ L2) 
    \/ L1) 
    \/ ( 
    LSeg (p00,p2)))) 
    = ((( 
    LSeg (p1,p10)) 
    /\ ((L4 
    \/ L2) 
    \/ L1)) 
    \/ (( 
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p00,p2)))) by 
    XBOOLE_1: 23
    
            .= (((
    LSeg (p1,p10)) 
    /\ (L4 
    \/ L2)) 
    \/ (( 
    LSeg (p1,p10)) 
    /\ L1)) by 
    A183,
    XBOOLE_1: 23
    
            .= (((
    LSeg (p1,p10)) 
    /\ L4) 
    \/ (( 
    LSeg (p1,p10)) 
    /\ L2)) by 
    A173,
    XBOOLE_1: 23
    
            .=
    {p10} by
    A182,
    A190,
    A165,
    ZFMISC_1: 33;
    
            hence P2
    is_an_arc_of (p1,p2) by 
    A191,
    TOPREAL1: 11;
    
            
    
            
    
    A193: p1 
    in ( 
    LSeg (p1,p10)) by 
    RLTOPSP1: 68;
    
            
    
            thus (P1
    \/ P2) 
    = ((( 
    LSeg (p2,p1)) 
    \/ ( 
    LSeg (p1,p10))) 
    \/ (((L4 
    \/ L2) 
    \/ L1) 
    \/ ( 
    LSeg (p00,p2)))) by 
    XBOOLE_1: 4
    
            .= (((
    LSeg (p00,p2)) 
    \/ (( 
    LSeg (p2,p1)) 
    \/ ( 
    LSeg (p1,p10)))) 
    \/ ((L4 
    \/ L2) 
    \/ L1)) by 
    XBOOLE_1: 4
    
            .= (L3
    \/ ((L4 
    \/ L2) 
    \/ L1)) by 
    A3,
    A101,
    TOPREAL1: 7
    
            .= (L3
    \/ (L4 
    \/ (L1 
    \/ L2))) by 
    XBOOLE_1: 4
    
            .=
    R^2-unit_square by 
    TOPREAL1:def 2,
    XBOOLE_1: 4;
    
            (L3
    /\ L2) 
    =  
    {} by 
    TOPREAL1: 19,
    XBOOLE_0:def 7;
    
            then
    
            
    
    A194: (( 
    LSeg (p1,p2)) 
    /\ L2) 
    =  
    {} by 
    A103,
    XBOOLE_1: 3,
    XBOOLE_1: 26;
    
            p2
    in ( 
    LSeg (p1,p2)) by 
    RLTOPSP1: 68;
    
            then p2
    in (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p00,p2))) by 
    A192,
    XBOOLE_0:def 4;
    
            then
    {p2}
    c= (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p00,p2))) by 
    ZFMISC_1: 31;
    
            then
    
            
    
    A195: (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p00,p2))) 
    =  
    {p2} by
    A159,
    XBOOLE_0:def 10;
    
            p1
    in ( 
    LSeg (p1,p2)) by 
    RLTOPSP1: 68;
    
            then p1
    in (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p1,p10))) by 
    A193,
    XBOOLE_0:def 4;
    
            then
    {p1}
    c= (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p1,p10))) by 
    ZFMISC_1: 31;
    
            then ((
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p1,p10))) 
    =  
    {p1} by
    A176,
    XBOOLE_0:def 10;
    
            
    
            then
    
            
    
    A196: (P1 
    /\ P2) 
    = ( 
    {p1}
    \/ (( 
    LSeg (p1,p2)) 
    /\ (((L4 
    \/ L2) 
    \/ L1) 
    \/ ( 
    LSeg (p00,p2))))) by 
    XBOOLE_1: 23
    
            .= (
    {p1}
    \/ ((( 
    LSeg (p1,p2)) 
    /\ ((L4 
    \/ L2) 
    \/ L1)) 
    \/  
    {p2})) by
    A195,
    XBOOLE_1: 23
    
            .= (
    {p1}
    \/ (((( 
    LSeg (p1,p2)) 
    /\ (L4 
    \/ L2)) 
    \/ (( 
    LSeg (p1,p2)) 
    /\ L1)) 
    \/  
    {p2})) by
    XBOOLE_1: 23
    
            .= (
    {p1}
    \/ ((((( 
    LSeg (p1,p2)) 
    /\ L4) 
    \/ (( 
    LSeg (p1,p2)) 
    /\ L2)) 
    \/ (( 
    LSeg (p1,p2)) 
    /\ L1)) 
    \/  
    {p2})) by
    XBOOLE_1: 23
    
            .= (
    {p1}
    \/ ((( 
    LSeg (p1,p2)) 
    /\ L4) 
    \/ ((( 
    LSeg (p1,p2)) 
    /\ L1) 
    \/  
    {p2}))) by
    A194,
    XBOOLE_1: 4
    
            .= ((
    {p1}
    \/ (( 
    LSeg (p1,p2)) 
    /\ L4)) 
    \/ ((( 
    LSeg (p1,p2)) 
    /\ L1) 
    \/  
    {p2})) by
    XBOOLE_1: 4;
    
            
    
    A197: 
    
            now
    
              per cases ;
    
                suppose
    
                
    
    A198: p2 
    = p00; 
    
                p2
    in ( 
    LSeg (p1,p2)) by 
    RLTOPSP1: 68;
    
                then
    
                
    
    A199: (( 
    LSeg (p1,p2)) 
    /\ L1) 
    <>  
    {} by 
    A198,
    Lm20,
    XBOOLE_0:def 4;
    
                ((
    LSeg (p1,p2)) 
    /\ L1) 
    c= (L3 
    /\ L1) by 
    A3,
    A101,
    TOPREAL1: 6,
    XBOOLE_1: 26;
    
                then ((
    LSeg (p1,p2)) 
    /\ L1) 
    =  
    {p2} by
    A198,
    A199,
    TOPREAL1: 17,
    ZFMISC_1: 33;
    
                hence (P1
    /\ P2) 
    = (( 
    {p1}
    \/ (( 
    LSeg (p1,p2)) 
    /\ L4)) 
    \/  
    {p2}) by
    A196;
    
              end;
    
                suppose
    
                
    
    A200: p2 
    <> p00; 
    
                now
    
                  assume p00
    in (( 
    LSeg (p1,p2)) 
    /\ L1); 
    
                  then p00
    in ( 
    LSeg (p2,p1)) by 
    XBOOLE_0:def 4;
    
                  then (p2
    `1 ) 
    =  
    0 by 
    A14,
    A104,
    A106,
    A158,
    Lm4,
    TOPREAL1: 3;
    
                  hence contradiction by
    A104,
    A107,
    A200,
    EUCLID: 53;
    
                end;
    
                then
    
                
    
    A201: 
    {p00}
    <> (( 
    LSeg (p1,p2)) 
    /\ L1) by 
    ZFMISC_1: 31;
    
                ((
    LSeg (p1,p2)) 
    /\ L1) 
    c= (L3 
    /\ L1) by 
    A3,
    A101,
    TOPREAL1: 6,
    XBOOLE_1: 26;
    
                then ((
    LSeg (p1,p2)) 
    /\ L1) 
    =  
    {} by 
    A201,
    TOPREAL1: 17,
    ZFMISC_1: 33;
    
                hence (P1
    /\ P2) 
    = (( 
    {p1}
    \/ (( 
    LSeg (p1,p2)) 
    /\ L4)) 
    \/  
    {p2}) by
    A196;
    
              end;
    
            end;
    
            now
    
              per cases ;
    
                suppose
    
                
    
    A202: p1 
    = p10; 
    
                p1
    in ( 
    LSeg (p1,p2)) by 
    RLTOPSP1: 68;
    
                then
    
                
    
    A203: (( 
    LSeg (p1,p2)) 
    /\ L4) 
    <>  
    {} by 
    A202,
    Lm25,
    XBOOLE_0:def 4;
    
                ((
    LSeg (p1,p2)) 
    /\ L4) 
    c=  
    {p1} by
    A3,
    A101,
    A202,
    TOPREAL1: 6,
    TOPREAL1: 16,
    XBOOLE_1: 26;
    
                then ((
    LSeg (p1,p2)) 
    /\ L4) 
    =  
    {p1} by
    A203,
    ZFMISC_1: 33;
    
                hence (P1
    /\ P2) 
    =  
    {p1, p2} by
    A197,
    ENUMSET1: 1;
    
              end;
    
                suppose
    
                
    
    A204: p1 
    <> p10; 
    
                now
    
                  assume p10
    in (( 
    LSeg (p1,p2)) 
    /\ L4); 
    
                  then p10
    in ( 
    LSeg (p2,p1)) by 
    XBOOLE_0:def 4;
    
                  then (p10
    `1 ) 
    <= (p1 
    `1 ) by 
    A14,
    A104,
    A158,
    TOPREAL1: 3;
    
                  then (p1
    `1 ) 
    = 1 by 
    A14,
    A15,
    Lm8,
    XXREAL_0: 1;
    
                  hence contradiction by
    A14,
    A17,
    A204,
    EUCLID: 53;
    
                end;
    
                then
    
                
    
    A205: 
    {p10}
    <> (( 
    LSeg (p1,p2)) 
    /\ L4) by 
    ZFMISC_1: 31;
    
                ((
    LSeg (p1,p2)) 
    /\ L4) 
    c=  
    {p10} by
    A3,
    A101,
    TOPREAL1: 6,
    TOPREAL1: 16,
    XBOOLE_1: 26;
    
                then ((
    LSeg (p1,p2)) 
    /\ L4) 
    =  
    {} by 
    A205,
    ZFMISC_1: 33;
    
                hence (P1
    /\ P2) 
    =  
    {p1, p2} by
    A197,
    ENUMSET1: 1;
    
              end;
    
            end;
    
            hence (P1
    /\ P2) 
    =  
    {p1, p2};
    
          end;
    
        end;
    
        hence thesis;
    
      end;
    
        suppose
    
        
    
    A206: p2 
    in L4; 
    
        then
    
        
    
    A207: ex q st q 
    = p2 & (q 
    `1 ) 
    = 1 & (q 
    `2 ) 
    <= 1 & (q 
    `2 ) 
    >=  
    0 by 
    TOPREAL1: 13;
    
        now
    
          assume
    
          
    
    A208: p10 
    in (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p11,p2))); 
    
          then
    
          
    
    A209: p10 
    in ( 
    LSeg (p00,p1)) by 
    XBOOLE_0:def 4;
    
          (p00
    `1 ) 
    <= (p1 
    `1 ) by 
    A14,
    A16,
    EUCLID: 52;
    
          then (p10
    `1 ) 
    <= (p1 
    `1 ) by 
    A209,
    TOPREAL1: 3;
    
          then 1
    = (p1 
    `1 ) by 
    A14,
    A15,
    Lm8,
    XXREAL_0: 1;
    
          then
    
          
    
    A210: p1 
    = p10 by 
    A14,
    A17,
    EUCLID: 53;
    
          
    
          
    
    A211: (p2 
    `2 ) 
    <= (p11 
    `2 ) by 
    A207,
    EUCLID: 52;
    
          p10
    in ( 
    LSeg (p2,p11)) by 
    A208,
    XBOOLE_0:def 4;
    
          then
    0  
    = (p2 
    `2 ) by 
    A207,
    A211,
    Lm9,
    TOPREAL1: 4;
    
          hence contradiction by
    A1,
    A207,
    A210,
    EUCLID: 53;
    
        end;
    
        then
    
        
    
    A212: 
    {p10}
    <> (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p11,p2))) by 
    ZFMISC_1: 31;
    
        
    
        
    
    A213: L2 
    is_an_arc_of (p01,p11) by 
    Lm6,
    Lm10,
    TOPREAL1: 9;
    
        L1
    is_an_arc_of (p00,p01) by 
    Lm5,
    Lm7,
    TOPREAL1: 9;
    
        then
    
        
    
    A214: (L1 
    \/ L2) 
    is_an_arc_of (p00,p11) by 
    A213,
    TOPREAL1: 2,
    TOPREAL1: 15;
    
        take P1 = ((
    LSeg (p1,p10)) 
    \/ ( 
    LSeg (p10,p2))), P2 = (( 
    LSeg (p1,p00)) 
    \/ ((L1 
    \/ L2) 
    \/ ( 
    LSeg (p11,p2)))); 
    
        
    
        
    
    A215: L3 
    = (( 
    LSeg (p1,p10)) 
    \/ ( 
    LSeg (p1,p00))) by 
    A3,
    TOPREAL1: 5;
    
        p11
    in ( 
    LSeg (p11,p2)) by 
    RLTOPSP1: 68;
    
        then
    
        
    
    A216: (L2 
    /\ ( 
    LSeg (p11,p2))) 
    <>  
    {} by 
    Lm26,
    XBOOLE_0:def 4;
    
        
    
        
    
    A217: p10 
    in ( 
    LSeg (p10,p2)) by 
    RLTOPSP1: 68;
    
        p10
    in ( 
    LSeg (p1,p10)) by 
    RLTOPSP1: 68;
    
        then
    
        
    
    A218: (( 
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p10,p2))) 
    <>  
    {} by 
    A217,
    XBOOLE_0:def 4;
    
        
    
        
    
    A219: ( 
    LSeg (p2,p10)) 
    c= L4 by 
    A206,
    Lm25,
    TOPREAL1: 6;
    
        then ((
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p10,p2))) 
    c= (L3 
    /\ L4) by 
    A12,
    XBOOLE_1: 27;
    
        then
    
        
    
    A220: (( 
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p10,p2))) 
    =  
    {p10} by
    A218,
    TOPREAL1: 16,
    ZFMISC_1: 33;
    
        p1
    <> p10 or p2 
    <> p10 by 
    A1;
    
        hence P1
    is_an_arc_of (p1,p2) by 
    A220,
    TOPREAL1: 12;
    
        
    
        
    
    A221: (( 
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p1,p00))) 
    =  
    {p1} by
    A3,
    TOPREAL1: 8;
    
        (L1
    /\ L4) 
    =  
    {} by 
    TOPREAL1: 20,
    XBOOLE_0:def 7;
    
        then
    
        
    
    A222: (( 
    LSeg (p10,p2)) 
    /\ L1) 
    =  
    {} by 
    A219,
    XBOOLE_1: 3,
    XBOOLE_1: 26;
    
        
    
        
    
    A223: ( 
    LSeg (p2,p11)) 
    c= L4 by 
    A206,
    Lm27,
    TOPREAL1: 6;
    
        then
    
        
    
    A224: (L2 
    /\ ( 
    LSeg (p11,p2))) 
    c=  
    {p11} by
    TOPREAL1: 18,
    XBOOLE_1: 27;
    
        
    
        
    
    A225: (L1 
    /\ ( 
    LSeg (p11,p2))) 
    =  
    {} by 
    A223,
    Lm3,
    XBOOLE_1: 3,
    XBOOLE_1: 26;
    
        ((L1
    \/ L2) 
    /\ ( 
    LSeg (p11,p2))) 
    = ((L1 
    /\ ( 
    LSeg (p11,p2))) 
    \/ (L2 
    /\ ( 
    LSeg (p11,p2)))) by 
    XBOOLE_1: 23
    
        .=
    {p11} by
    A225,
    A224,
    A216,
    ZFMISC_1: 33;
    
        then
    
        
    
    A226: ((L1 
    \/ L2) 
    \/ ( 
    LSeg (p11,p2))) 
    is_an_arc_of (p00,p2) by 
    A214,
    TOPREAL1: 10;
    
        
    
        
    
    A227: (( 
    LSeg (p10,p2)) 
    /\ ( 
    LSeg (p11,p2))) 
    =  
    {p2} by
    A206,
    TOPREAL1: 8;
    
        
    
        
    
    A228: L4 
    = (( 
    LSeg (p11,p2)) 
    \/ ( 
    LSeg (p10,p2))) by 
    A206,
    TOPREAL1: 5;
    
        ((
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p11,p2))) 
    c=  
    {p10} by
    A10,
    A223,
    TOPREAL1: 16,
    XBOOLE_1: 27;
    
        then
    
        
    
    A229: (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p11,p2))) 
    =  
    {} by 
    A212,
    ZFMISC_1: 33;
    
        ((
    LSeg (p1,p00)) 
    /\ ((L1 
    \/ L2) 
    \/ ( 
    LSeg (p11,p2)))) 
    = ((( 
    LSeg (p1,p00)) 
    /\ (L1 
    \/ L2)) 
    \/ (( 
    LSeg (p1,p00)) 
    /\ ( 
    LSeg (p11,p2)))) by 
    XBOOLE_1: 23
    
        .= (((
    LSeg (p1,p00)) 
    /\ L1) 
    \/ (( 
    LSeg (p1,p00)) 
    /\ L2)) by 
    A229,
    XBOOLE_1: 23
    
        .=
    {p00} by
    A8,
    A6,
    A11,
    TOPREAL1: 17,
    ZFMISC_1: 33;
    
        hence P2
    is_an_arc_of (p1,p2) by 
    A226,
    TOPREAL1: 11;
    
        
    
        thus (P1
    \/ P2) 
    = (( 
    LSeg (p10,p2)) 
    \/ (( 
    LSeg (p1,p10)) 
    \/ (( 
    LSeg (p1,p00)) 
    \/ ((L1 
    \/ L2) 
    \/ ( 
    LSeg (p11,p2)))))) by 
    XBOOLE_1: 4
    
        .= ((
    LSeg (p10,p2)) 
    \/ (L3 
    \/ ((L1 
    \/ L2) 
    \/ ( 
    LSeg (p11,p2))))) by 
    A215,
    XBOOLE_1: 4
    
        .= ((((L1
    \/ L2) 
    \/ L3) 
    \/ ( 
    LSeg (p11,p2))) 
    \/ ( 
    LSeg (p10,p2))) by 
    XBOOLE_1: 4
    
        .= (((L1
    \/ L2) 
    \/ L3) 
    \/ L4) by 
    A228,
    XBOOLE_1: 4
    
        .=
    R^2-unit_square by 
    TOPREAL1:def 2,
    XBOOLE_1: 4;
    
        
    
        
    
    A230: (P1 
    /\ P2) 
    = ((( 
    LSeg (p1,p10)) 
    /\ (( 
    LSeg (p1,p00)) 
    \/ ((L1 
    \/ L2) 
    \/ ( 
    LSeg (p11,p2))))) 
    \/ (( 
    LSeg (p10,p2)) 
    /\ (( 
    LSeg (p1,p00)) 
    \/ ((L1 
    \/ L2) 
    \/ ( 
    LSeg (p11,p2)))))) by 
    XBOOLE_1: 23
    
        .= ((((
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p1,p00))) 
    \/ (( 
    LSeg (p1,p10)) 
    /\ ((L1 
    \/ L2) 
    \/ ( 
    LSeg (p11,p2))))) 
    \/ (( 
    LSeg (p10,p2)) 
    /\ (( 
    LSeg (p1,p00)) 
    \/ ((L1 
    \/ L2) 
    \/ ( 
    LSeg (p11,p2)))))) by 
    XBOOLE_1: 23
    
        .= ((
    {p1}
    \/ ((( 
    LSeg (p1,p10)) 
    /\ (L1 
    \/ L2)) 
    \/ (( 
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p11,p2))))) 
    \/ (( 
    LSeg (p10,p2)) 
    /\ (( 
    LSeg (p1,p00)) 
    \/ ((L1 
    \/ L2) 
    \/ ( 
    LSeg (p11,p2)))))) by 
    A221,
    XBOOLE_1: 23
    
        .= ((
    {p1}
    \/ (((( 
    LSeg (p1,p10)) 
    /\ L1) 
    \/ (( 
    LSeg (p10,p1)) 
    /\ L2)) 
    \/ (( 
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p11,p2))))) 
    \/ (( 
    LSeg (p10,p2)) 
    /\ (( 
    LSeg (p1,p00)) 
    \/ ((L1 
    \/ L2) 
    \/ ( 
    LSeg (p11,p2)))))) by 
    XBOOLE_1: 23
    
        .= ((
    {p1}
    \/ ((( 
    LSeg (p1,p10)) 
    /\ L1) 
    \/ (( 
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p11,p2))))) 
    \/ ((( 
    LSeg (p10,p2)) 
    /\ ( 
    LSeg (p1,p00))) 
    \/ (( 
    LSeg (p10,p2)) 
    /\ ((L1 
    \/ L2) 
    \/ ( 
    LSeg (p11,p2)))))) by 
    A13,
    XBOOLE_1: 23
    
        .= ((
    {p1}
    \/ ((( 
    LSeg (p1,p10)) 
    /\ L1) 
    \/ (( 
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p11,p2))))) 
    \/ ((( 
    LSeg (p10,p2)) 
    /\ ( 
    LSeg (p1,p00))) 
    \/ ((( 
    LSeg (p10,p2)) 
    /\ (L1 
    \/ L2)) 
    \/  
    {p2}))) by
    A227,
    XBOOLE_1: 23
    
        .= ((
    {p1}
    \/ ((( 
    LSeg (p1,p10)) 
    /\ L1) 
    \/ (( 
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p11,p2))))) 
    \/ ((( 
    LSeg (p10,p2)) 
    /\ ( 
    LSeg (p1,p00))) 
    \/ (((( 
    LSeg (p10,p2)) 
    /\ L1) 
    \/ (( 
    LSeg (p10,p2)) 
    /\ L2)) 
    \/  
    {p2}))) by
    XBOOLE_1: 23
    
        .= ((
    {p1}
    \/ ((( 
    LSeg (p1,p10)) 
    /\ L1) 
    \/ (( 
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p11,p2))))) 
    \/ ((( 
    LSeg (p10,p2)) 
    /\ ( 
    LSeg (p1,p00))) 
    \/ ((( 
    LSeg (p10,p2)) 
    /\ L2) 
    \/  
    {p2}))) by
    A222;
    
        
    
    A231: 
    
        now
    
          per cases ;
    
            suppose
    
            
    
    A232: p1 
    = p00; 
    
            then
    
            
    
    A233: (( 
    LSeg (p10,p2)) 
    /\ ( 
    LSeg (p1,p00))) 
    = (( 
    LSeg (p10,p2)) 
    /\  
    {p00}) by
    RLTOPSP1: 70;
    
             not p00
    in ( 
    LSeg (p10,p2)) by 
    A219,
    Lm4,
    Lm8,
    Lm10,
    TOPREAL1: 3;
    
            then ((
    LSeg (p10,p2)) 
    /\ ( 
    LSeg (p1,p00))) 
    =  
    {} by 
    A233,
    Lm1;
    
            
    
            hence (P1
    /\ P2) 
    = ((( 
    {p1}
    \/  
    {p1})
    \/ (( 
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p11,p2)))) 
    \/ ((( 
    LSeg (p10,p2)) 
    /\ L2) 
    \/  
    {p2})) by
    A230,
    A232,
    TOPREAL1: 17,
    XBOOLE_1: 4
    
            .= ((
    {p1}
    \/ (( 
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p11,p2)))) 
    \/ ((( 
    LSeg (p10,p2)) 
    /\ L2) 
    \/  
    {p2}));
    
          end;
    
            suppose
    
            
    
    A234: p1 
    = p10; 
    
            
    
            
    
    A235: p1 
    in ( 
    LSeg (p1,p00)) by 
    RLTOPSP1: 68;
    
            p1
    in ( 
    LSeg (p10,p2)) by 
    A234,
    RLTOPSP1: 68;
    
            then
    
            
    
    A236: 
    {}  
    <> (( 
    LSeg (p10,p2)) 
    /\ ( 
    LSeg (p1,p00))) by 
    A235,
    XBOOLE_0:def 4;
    
            ((
    LSeg (p1,p10)) 
    /\ L1) 
    = ( 
    {p10}
    /\ L1) by 
    A234,
    RLTOPSP1: 70;
    
            then
    
            
    
    A237: (( 
    LSeg (p1,p10)) 
    /\ L1) 
    =  
    {} by 
    Lm1,
    Lm16;
    
            ((
    LSeg (p10,p2)) 
    /\ ( 
    LSeg (p1,p00))) 
    c= (L4 
    /\ L3) by 
    A10,
    A219,
    XBOOLE_1: 27;
    
            then ((
    LSeg (p10,p2)) 
    /\ ( 
    LSeg (p1,p00))) 
    =  
    {p1} by
    A234,
    A236,
    TOPREAL1: 16,
    ZFMISC_1: 33;
    
            
    
            hence (P1
    /\ P2) 
    = (( 
    {p1}
    \/ ( 
    {p1}
    \/ (( 
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p11,p2))))) 
    \/ ((( 
    LSeg (p10,p2)) 
    /\ L2) 
    \/  
    {p2})) by
    A230,
    A237,
    XBOOLE_1: 4
    
            .= (((
    {p1}
    \/  
    {p1})
    \/ (( 
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p11,p2)))) 
    \/ ((( 
    LSeg (p10,p2)) 
    /\ L2) 
    \/  
    {p2})) by
    XBOOLE_1: 4
    
            .= ((
    {p1}
    \/ (( 
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p11,p2)))) 
    \/ ((( 
    LSeg (p10,p2)) 
    /\ L2) 
    \/  
    {p2}));
    
          end;
    
            suppose
    
            
    
    A238: p1 
    <> p10 & p1 
    <> p00; 
    
            now
    
              assume p10
    in (( 
    LSeg (p10,p2)) 
    /\ ( 
    LSeg (p1,p00))); 
    
              then
    
              
    
    A239: p10 
    in ( 
    LSeg (p00,p1)) by 
    XBOOLE_0:def 4;
    
              (p00
    `1 ) 
    <= (p1 
    `1 ) by 
    A14,
    A16,
    EUCLID: 52;
    
              then (p10
    `1 ) 
    <= (p1 
    `1 ) by 
    A239,
    TOPREAL1: 3;
    
              then (p1
    `1 ) 
    = 1 by 
    A14,
    A15,
    Lm8,
    XXREAL_0: 1;
    
              hence contradiction by
    A14,
    A17,
    A238,
    EUCLID: 53;
    
            end;
    
            then
    
            
    
    A240: 
    {p10}
    <> (( 
    LSeg (p10,p2)) 
    /\ ( 
    LSeg (p1,p00))) by 
    ZFMISC_1: 31;
    
            ((
    LSeg (p10,p2)) 
    /\ ( 
    LSeg (p1,p00))) 
    c= (L4 
    /\ L3) by 
    A10,
    A219,
    XBOOLE_1: 27;
    
            then
    
            
    
    A241: (( 
    LSeg (p10,p2)) 
    /\ ( 
    LSeg (p1,p00))) 
    =  
    {} by 
    A240,
    TOPREAL1: 16,
    ZFMISC_1: 33;
    
            now
    
              assume p00
    in (( 
    LSeg (p1,p10)) 
    /\ L1); 
    
              then
    
              
    
    A242: p00 
    in ( 
    LSeg (p1,p10)) by 
    XBOOLE_0:def 4;
    
              (p1
    `1 ) 
    <= (p10 
    `1 ) by 
    A14,
    A15,
    EUCLID: 52;
    
              then (p1
    `1 ) 
    =  
    0 by 
    A14,
    A16,
    A242,
    Lm4,
    TOPREAL1: 3;
    
              hence contradiction by
    A14,
    A17,
    A238,
    EUCLID: 53;
    
            end;
    
            then
    
            
    
    A243: 
    {p00}
    <> (( 
    LSeg (p1,p10)) 
    /\ L1) by 
    ZFMISC_1: 31;
    
            ((
    LSeg (p1,p10)) 
    /\ L1) 
    c= (L3 
    /\ L1) by 
    A3,
    Lm24,
    TOPREAL1: 6,
    XBOOLE_1: 26;
    
            then ((
    LSeg (p1,p10)) 
    /\ L1) 
    =  
    {} by 
    A243,
    TOPREAL1: 17,
    ZFMISC_1: 33;
    
            hence (P1
    /\ P2) 
    = (( 
    {p1}
    \/ (( 
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p11,p2)))) 
    \/ ((( 
    LSeg (p10,p2)) 
    /\ L2) 
    \/  
    {p2})) by
    A230,
    A241;
    
          end;
    
        end;
    
        now
    
          per cases ;
    
            suppose
    
            
    
    A244: p2 
    = p10; 
    
            p10
    in ( 
    LSeg (p1,p10)) by 
    RLTOPSP1: 68;
    
            then
    
            
    
    A245: 
    {}  
    <> (( 
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p11,p2))) by 
    A244,
    Lm25,
    XBOOLE_0:def 4;
    
            ((
    LSeg (p10,p2)) 
    /\ L2) 
    = ( 
    {p10}
    /\ L2) by 
    A244,
    RLTOPSP1: 70;
    
            then
    
            
    
    A246: (( 
    LSeg (p10,p2)) 
    /\ L2) 
    =  
    {} by 
    Lm1,
    Lm17;
    
            ((
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p11,p2))) 
    c=  
    {p2} by
    A12,
    A244,
    TOPREAL1: 16,
    XBOOLE_1: 27;
    
            then ((
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p11,p2))) 
    =  
    {p2} by
    A245,
    ZFMISC_1: 33;
    
            
    
            hence (P1
    /\ P2) 
    = ( 
    {p1}
    \/ ( 
    {p2}
    \/  
    {p2})) by
    A231,
    A246,
    XBOOLE_1: 4
    
            .=
    {p1, p2} by
    ENUMSET1: 1;
    
          end;
    
            suppose
    
            
    
    A247: p2 
    = p11; 
    
            then
    
            
    
    A248: (( 
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p11,p2))) 
    = (( 
    LSeg (p1,p10)) 
    /\  
    {p11}) by
    RLTOPSP1: 70;
    
             not p11
    in ( 
    LSeg (p1,p10)) by 
    A12,
    Lm5,
    Lm9,
    Lm11,
    TOPREAL1: 4;
    
            then ((
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p11,p2))) 
    =  
    {} by 
    A248,
    Lm1;
    
            hence thesis by
    A231,
    A247,
    ENUMSET1: 1,
    TOPREAL1: 18;
    
          end;
    
            suppose
    
            
    
    A249: p2 
    <> p11 & p2 
    <> p10; 
    
            now
    
              assume p11
    in (( 
    LSeg (p10,p2)) 
    /\ L2); 
    
              then
    
              
    
    A250: p11 
    in ( 
    LSeg (p10,p2)) by 
    XBOOLE_0:def 4;
    
              (p10
    `2 ) 
    <= (p2 
    `2 ) by 
    A207,
    EUCLID: 52;
    
              then (p11
    `2 ) 
    <= (p2 
    `2 ) by 
    A250,
    TOPREAL1: 4;
    
              then 1
    = (p2 
    `2 ) by 
    A207,
    Lm11,
    XXREAL_0: 1;
    
              hence contradiction by
    A207,
    A249,
    EUCLID: 53;
    
            end;
    
            then
    
            
    
    A251: 
    {p11}
    <> (( 
    LSeg (p10,p2)) 
    /\ L2) by 
    ZFMISC_1: 31;
    
            ((
    LSeg (p10,p2)) 
    /\ L2) 
    c= (L4 
    /\ L2) by 
    A206,
    Lm25,
    TOPREAL1: 6,
    XBOOLE_1: 26;
    
            then
    
            
    
    A252: (( 
    LSeg (p10,p2)) 
    /\ L2) 
    =  
    {} by 
    A251,
    TOPREAL1: 18,
    ZFMISC_1: 33;
    
            now
    
              assume p10
    in (( 
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p11,p2))); 
    
              then
    
              
    
    A253: p10 
    in ( 
    LSeg (p2,p11)) by 
    XBOOLE_0:def 4;
    
              (p2
    `2 ) 
    <= (p11 
    `2 ) by 
    A207,
    EUCLID: 52;
    
              then (p2
    `2 ) 
    =  
    0 by 
    A207,
    A253,
    Lm9,
    TOPREAL1: 4;
    
              hence contradiction by
    A207,
    A249,
    EUCLID: 53;
    
            end;
    
            then
    
            
    
    A254: 
    {p10}
    <> (( 
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p11,p2))) by 
    ZFMISC_1: 31;
    
            ((
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p11,p2))) 
    c=  
    {p10} by
    A12,
    A223,
    TOPREAL1: 16,
    XBOOLE_1: 27;
    
            then ((
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p11,p2))) 
    =  
    {} by 
    A254,
    ZFMISC_1: 33;
    
            hence thesis by
    A231,
    A252,
    ENUMSET1: 1;
    
          end;
    
        end;
    
        hence thesis;
    
      end;
    
    end;
    
    
    
    
    
    Lm33: p1 
    <> p2 & p2 
    in  
    R^2-unit_square & p1 
    in ( 
    LSeg (p10,p11)) implies ex P1,P2 be non 
    empty  
    Subset of ( 
    TOP-REAL 2) st P1 
    is_an_arc_of (p1,p2) & P2 
    is_an_arc_of (p1,p2) & 
    R^2-unit_square  
    = (P1 
    \/ P2) & (P1 
    /\ P2) 
    =  
    {p1, p2}
    
    proof
    
      assume that
    
      
    
    A1: p1 
    <> p2 and 
    
      
    
    A2: p2 
    in  
    R^2-unit_square and 
    
      
    
    A3: p1 
    in ( 
    LSeg (p10,p11)); 
    
      
    
      
    
    A4: p2 
    in (L1 
    \/ L2) or p2 
    in (L3 
    \/ L4) by 
    A2,
    TOPREAL1:def 2,
    XBOOLE_0:def 3;
    
      
    
      
    
    A5: ( 
    LSeg (p1,p11)) 
    c= L4 by 
    A3,
    Lm27,
    TOPREAL1: 6;
    
      p11
    in ( 
    LSeg (p1,p11)) by 
    RLTOPSP1: 68;
    
      then
    
      
    
    A6: 
    {}  
    <> (( 
    LSeg (p1,p11)) 
    /\ L2) by 
    Lm26,
    XBOOLE_0:def 4;
    
      p10
    in ( 
    LSeg (p1,p10)) by 
    RLTOPSP1: 68;
    
      then
    
      
    
    A7: 
    {}  
    <> (( 
    LSeg (p1,p10)) 
    /\ L3) by 
    Lm24,
    XBOOLE_0:def 4;
    
      
    
      
    
    A8: (( 
    LSeg (p1,p11)) 
    /\ L2) 
    c= (L4 
    /\ L2) by 
    A3,
    Lm27,
    TOPREAL1: 6,
    XBOOLE_1: 26;
    
      
    
      
    
    A9: (( 
    LSeg (p1,p10)) 
    /\ L3) 
    c= (L4 
    /\ L3) by 
    A3,
    Lm25,
    TOPREAL1: 6,
    XBOOLE_1: 26;
    
      (L1
    /\ L4) 
    =  
    {} by 
    TOPREAL1: 20,
    XBOOLE_0:def 7;
    
      then
    
      
    
    A10: (( 
    LSeg (p1,p11)) 
    /\ L1) 
    =  
    {} by 
    A5,
    XBOOLE_1: 3,
    XBOOLE_1: 26;
    
      
    
      
    
    A11: ( 
    LSeg (p1,p10)) 
    c= L4 by 
    A3,
    Lm25,
    TOPREAL1: 6;
    
      (L1
    /\ L4) 
    =  
    {} by 
    TOPREAL1: 20,
    XBOOLE_0:def 7;
    
      then
    
      
    
    A12: (( 
    LSeg (p10,p1)) 
    /\ L1) 
    =  
    {} by 
    A11,
    XBOOLE_1: 3,
    XBOOLE_1: 26;
    
      consider p such that
    
      
    
    A13: p 
    = p1 and 
    
      
    
    A14: (p 
    `1 ) 
    = 1 and 
    
      
    
    A15: (p 
    `2 ) 
    <= 1 and 
    
      
    
    A16: (p 
    `2 ) 
    >=  
    0 by 
    A3,
    TOPREAL1: 13;
    
      per cases by
    A4,
    XBOOLE_0:def 3;
    
        suppose
    
        
    
    A17: p2 
    in L1; 
    
        p00
    in ( 
    LSeg (p00,p2)) by 
    RLTOPSP1: 68;
    
        then
    
        
    
    A18: (L3 
    /\ ( 
    LSeg (p00,p2))) 
    <>  
    {} by 
    Lm21,
    XBOOLE_0:def 4;
    
        (L3
    /\ ( 
    LSeg (p00,p2))) 
    c= (L3 
    /\ L1) by 
    A17,
    Lm20,
    TOPREAL1: 6,
    XBOOLE_1: 26;
    
        then (L3
    /\ ( 
    LSeg (p00,p2))) 
    =  
    {p00} by
    A18,
    TOPREAL1: 17,
    ZFMISC_1: 33;
    
        then
    
        
    
    A19: (L3 
    \/ ( 
    LSeg (p00,p2))) 
    is_an_arc_of (p10,p2) by 
    Lm4,
    Lm8,
    TOPREAL1: 9,
    TOPREAL1: 10;
    
        
    
        
    
    A20: ( 
    LSeg (p2,p00)) 
    c= L1 by 
    A17,
    Lm20,
    TOPREAL1: 6;
    
        then
    
        
    
    A21: (( 
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p00,p2))) 
    =  
    {} by 
    A11,
    Lm3,
    XBOOLE_1: 3,
    XBOOLE_1: 27;
    
        
    
        
    
    A22: ( 
    LSeg (p2,p01)) 
    c= L1 by 
    A17,
    Lm22,
    TOPREAL1: 6;
    
        then
    
        
    
    A23: (( 
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p01,p2))) 
    =  
    {} by 
    A5,
    Lm3,
    XBOOLE_1: 3,
    XBOOLE_1: 27;
    
        (L1
    /\ L4) 
    =  
    {} by 
    TOPREAL1: 20,
    XBOOLE_0:def 7;
    
        then
    
        
    
    A24: (( 
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p00,p2))) 
    =  
    {} by 
    A5,
    A20,
    XBOOLE_1: 3,
    XBOOLE_1: 27;
    
        (L1
    /\ L4) 
    =  
    {} by 
    TOPREAL1: 20,
    XBOOLE_0:def 7;
    
        then
    
        
    
    A25: (( 
    LSeg (p01,p2)) 
    /\ ( 
    LSeg (p1,p10))) 
    =  
    {} by 
    A11,
    A22,
    XBOOLE_1: 3,
    XBOOLE_1: 27;
    
        
    
        
    
    A26: (( 
    LSeg (p01,p2)) 
    /\ ( 
    LSeg (p00,p2))) 
    =  
    {p2} by
    A17,
    TOPREAL1: 8;
    
        p01
    in ( 
    LSeg (p01,p2)) by 
    RLTOPSP1: 68;
    
        then
    
        
    
    A27: p01 
    in (L2 
    /\ ( 
    LSeg (p01,p2))) by 
    Lm23,
    XBOOLE_0:def 4;
    
        (L2
    /\ ( 
    LSeg (p01,p2))) 
    c= (L2 
    /\ L1) by 
    A17,
    Lm22,
    TOPREAL1: 6,
    XBOOLE_1: 26;
    
        then (L2
    /\ ( 
    LSeg (p01,p2))) 
    =  
    {p01} by
    A27,
    TOPREAL1: 15,
    ZFMISC_1: 33;
    
        then
    
        
    
    A28: (L2 
    \/ ( 
    LSeg (p01,p2))) 
    is_an_arc_of (p11,p2) by 
    Lm6,
    Lm10,
    TOPREAL1: 9,
    TOPREAL1: 10;
    
        take P1 = (((
    LSeg (p1,p11)) 
    \/ L2) 
    \/ ( 
    LSeg (p01,p2))), P2 = ((( 
    LSeg (p1,p10)) 
    \/ L3) 
    \/ ( 
    LSeg (p00,p2))); 
    
        
    
        
    
    A29: (( 
    LSeg (p1,p11)) 
    \/ ( 
    LSeg (p1,p10))) 
    = L4 by 
    A3,
    TOPREAL1: 5;
    
        ((
    LSeg (p1,p11)) 
    /\ (L2 
    \/ ( 
    LSeg (p01,p2)))) 
    = ((( 
    LSeg (p1,p11)) 
    /\ L2) 
    \/ (( 
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p01,p2)))) by 
    XBOOLE_1: 23
    
        .=
    {p11} by
    A8,
    A6,
    A23,
    TOPREAL1: 18,
    ZFMISC_1: 33;
    
        then ((
    LSeg (p1,p11)) 
    \/ (L2 
    \/ ( 
    LSeg (p01,p2)))) 
    is_an_arc_of (p1,p2) by 
    A28,
    TOPREAL1: 11;
    
        hence P1
    is_an_arc_of (p1,p2) by 
    XBOOLE_1: 4;
    
        
    
        
    
    A30: ex q st q 
    = p2 & (q 
    `1 ) 
    =  
    0 & (q 
    `2 ) 
    <= 1 & (q 
    `2 ) 
    >=  
    0 by 
    A17,
    TOPREAL1: 13;
    
        ((
    LSeg (p1,p10)) 
    /\ (L3 
    \/ ( 
    LSeg (p00,p2)))) 
    = ((( 
    LSeg (p1,p10)) 
    /\ L3) 
    \/ (( 
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p00,p2)))) by 
    XBOOLE_1: 23
    
        .=
    {p10} by
    A9,
    A7,
    A21,
    TOPREAL1: 16,
    ZFMISC_1: 33;
    
        then ((
    LSeg (p1,p10)) 
    \/ (L3 
    \/ ( 
    LSeg (p00,p2)))) 
    is_an_arc_of (p1,p2) by 
    A19,
    TOPREAL1: 11;
    
        hence P2
    is_an_arc_of (p1,p2) by 
    XBOOLE_1: 4;
    
        
    
        thus
    R^2-unit_square  
    = (((( 
    LSeg (p00,p2)) 
    \/ ( 
    LSeg (p01,p2))) 
    \/ L2) 
    \/ (L3 
    \/ L4)) by 
    A17,
    TOPREAL1: 5,
    TOPREAL1:def 2
    
        .= (((
    LSeg (p00,p2)) 
    \/ (( 
    LSeg (p01,p2)) 
    \/ L2)) 
    \/ (L3 
    \/ L4)) by 
    XBOOLE_1: 4
    
        .= ((L2
    \/ ( 
    LSeg (p01,p2))) 
    \/ ((L4 
    \/ L3) 
    \/ ( 
    LSeg (p00,p2)))) by 
    XBOOLE_1: 4
    
        .= ((L2
    \/ ( 
    LSeg (p01,p2))) 
    \/ (L4 
    \/ (L3 
    \/ ( 
    LSeg (p00,p2))))) by 
    XBOOLE_1: 4
    
        .= ((L2
    \/ ( 
    LSeg (p01,p2))) 
    \/ (( 
    LSeg (p1,p11)) 
    \/ (( 
    LSeg (p1,p10)) 
    \/ (L3 
    \/ ( 
    LSeg (p00,p2)))))) by 
    A29,
    XBOOLE_1: 4
    
        .= ((L2
    \/ ( 
    LSeg (p01,p2))) 
    \/ (( 
    LSeg (p1,p11)) 
    \/ ((( 
    LSeg (p1,p10)) 
    \/ L3) 
    \/ ( 
    LSeg (p00,p2))))) by 
    XBOOLE_1: 4
    
        .= (((
    LSeg (p1,p11)) 
    \/ (L2 
    \/ ( 
    LSeg (p01,p2)))) 
    \/ ((( 
    LSeg (p1,p10)) 
    \/ L3) 
    \/ ( 
    LSeg (p00,p2)))) by 
    XBOOLE_1: 4
    
        .= (P1
    \/ P2) by 
    XBOOLE_1: 4;
    
        
    
        
    
    A31: (( 
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p1,p10))) 
    =  
    {p1} by
    A3,
    TOPREAL1: 8;
    
        
    
        
    
    A32: (P1 
    /\ P2) 
    = (((( 
    LSeg (p1,p11)) 
    \/ L2) 
    /\ ((( 
    LSeg (p1,p10)) 
    \/ L3) 
    \/ ( 
    LSeg (p00,p2)))) 
    \/ (( 
    LSeg (p01,p2)) 
    /\ ((( 
    LSeg (p1,p10)) 
    \/ L3) 
    \/ ( 
    LSeg (p00,p2))))) by 
    XBOOLE_1: 23
    
        .= ((((
    LSeg (p1,p11)) 
    \/ L2) 
    /\ ((( 
    LSeg (p1,p10)) 
    \/ L3) 
    \/ ( 
    LSeg (p00,p2)))) 
    \/ ((( 
    LSeg (p01,p2)) 
    /\ (( 
    LSeg (p1,p10)) 
    \/ L3)) 
    \/  
    {p2})) by
    A26,
    XBOOLE_1: 23
    
        .= ((((
    LSeg (p1,p11)) 
    \/ L2) 
    /\ ((( 
    LSeg (p1,p10)) 
    \/ L3) 
    \/ ( 
    LSeg (p00,p2)))) 
    \/ (((( 
    LSeg (p01,p2)) 
    /\ ( 
    LSeg (p1,p10))) 
    \/ (( 
    LSeg (p01,p2)) 
    /\ L3)) 
    \/  
    {p2})) by
    XBOOLE_1: 23
    
        .= ((((
    LSeg (p1,p11)) 
    /\ ((( 
    LSeg (p1,p10)) 
    \/ L3) 
    \/ ( 
    LSeg (p00,p2)))) 
    \/ (L2 
    /\ ((( 
    LSeg (p1,p10)) 
    \/ L3) 
    \/ ( 
    LSeg (p00,p2))))) 
    \/ ((( 
    LSeg (p01,p2)) 
    /\ L3) 
    \/  
    {p2})) by
    A25,
    XBOOLE_1: 23
    
        .= ((((
    LSeg (p1,p11)) 
    /\ ((( 
    LSeg (p1,p10)) 
    \/ L3) 
    \/ ( 
    LSeg (p00,p2)))) 
    \/ ((L2 
    /\ (( 
    LSeg (p1,p10)) 
    \/ L3)) 
    \/ (L2 
    /\ ( 
    LSeg (p00,p2))))) 
    \/ ((( 
    LSeg (p01,p2)) 
    /\ L3) 
    \/  
    {p2})) by
    XBOOLE_1: 23
    
        .= ((((
    LSeg (p1,p11)) 
    /\ ((( 
    LSeg (p1,p10)) 
    \/ L3) 
    \/ ( 
    LSeg (p00,p2)))) 
    \/ (((L2 
    /\ ( 
    LSeg (p1,p10))) 
    \/ (L3 
    /\ L2)) 
    \/ (L2 
    /\ ( 
    LSeg (p00,p2))))) 
    \/ ((( 
    LSeg (p01,p2)) 
    /\ L3) 
    \/  
    {p2})) by
    XBOOLE_1: 23
    
        .= (((((
    LSeg (p1,p11)) 
    /\ (( 
    LSeg (p1,p10)) 
    \/ L3)) 
    \/ (( 
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p00,p2)))) 
    \/ ((L2 
    /\ ( 
    LSeg (p1,p10))) 
    \/ (L2 
    /\ ( 
    LSeg (p00,p2))))) 
    \/ ((( 
    LSeg (p01,p2)) 
    /\ L3) 
    \/  
    {p2})) by
    Lm2,
    XBOOLE_1: 23
    
        .= (((
    {p1}
    \/ (( 
    LSeg (p1,p11)) 
    /\ L3)) 
    \/ ((L2 
    /\ ( 
    LSeg (p1,p10))) 
    \/ (L2 
    /\ ( 
    LSeg (p00,p2))))) 
    \/ ((( 
    LSeg (p01,p2)) 
    /\ L3) 
    \/  
    {p2})) by
    A24,
    A31,
    XBOOLE_1: 23;
    
        
    
    A33: 
    
        now
    
          per cases ;
    
            suppose
    
            
    
    A34: p1 
    = p10; 
    
            then (L2
    /\ ( 
    LSeg (p1,p10))) 
    = (L2 
    /\  
    {p10}) by
    RLTOPSP1: 70;
    
            then (L2
    /\ ( 
    LSeg (p1,p10))) 
    =  
    {} by 
    Lm1,
    Lm17;
    
            hence (P1
    /\ P2) 
    = (( 
    {p1}
    \/ (L2 
    /\ ( 
    LSeg (p00,p2)))) 
    \/ ((( 
    LSeg (p01,p2)) 
    /\ L3) 
    \/  
    {p2})) by
    A32,
    A34,
    TOPREAL1: 16;
    
          end;
    
            suppose
    
            
    
    A35: p1 
    = p11; 
    
            then ((
    LSeg (p1,p11)) 
    /\ L3) 
    = ( 
    {p11}
    /\ L3) by 
    RLTOPSP1: 70;
    
            then ((
    LSeg (p1,p11)) 
    /\ L3) 
    =  
    {} by 
    Lm1,
    Lm19;
    
            
    
            hence (P1
    /\ P2) 
    = ((( 
    {p1}
    \/  
    {p1})
    \/ (L2 
    /\ ( 
    LSeg (p00,p2)))) 
    \/ ((( 
    LSeg (p01,p2)) 
    /\ L3) 
    \/  
    {p2})) by
    A32,
    A35,
    TOPREAL1: 18,
    XBOOLE_1: 4
    
            .= ((
    {p1}
    \/ (L2 
    /\ ( 
    LSeg (p00,p2)))) 
    \/ ((( 
    LSeg (p01,p2)) 
    /\ L3) 
    \/  
    {p2}));
    
          end;
    
            suppose
    
            
    
    A36: p1 
    <> p11 & p1 
    <> p10; 
    
            now
    
              assume p11
    in (L2 
    /\ ( 
    LSeg (p1,p10))); 
    
              then
    
              
    
    A37: p11 
    in ( 
    LSeg (p10,p1)) by 
    XBOOLE_0:def 4;
    
              (p10
    `2 ) 
    <= (p1 
    `2 ) by 
    A13,
    A16,
    EUCLID: 52;
    
              then (p11
    `2 ) 
    <= (p1 
    `2 ) by 
    A37,
    TOPREAL1: 4;
    
              then 1
    = (p1 
    `2 ) by 
    A13,
    A15,
    Lm11,
    XXREAL_0: 1;
    
              hence contradiction by
    A13,
    A14,
    A36,
    EUCLID: 53;
    
            end;
    
            then
    
            
    
    A38: 
    {p11}
    <> (L2 
    /\ ( 
    LSeg (p1,p10))) by 
    ZFMISC_1: 31;
    
            (L2
    /\ ( 
    LSeg (p1,p10))) 
    c=  
    {p11} by
    A3,
    Lm25,
    TOPREAL1: 6,
    TOPREAL1: 18,
    XBOOLE_1: 26;
    
            then
    
            
    
    A39: (L2 
    /\ ( 
    LSeg (p1,p10))) 
    =  
    {} by 
    A38,
    ZFMISC_1: 33;
    
            now
    
              assume p10
    in (( 
    LSeg (p1,p11)) 
    /\ L3); 
    
              then
    
              
    
    A40: p10 
    in ( 
    LSeg (p1,p11)) by 
    XBOOLE_0:def 4;
    
              (p1
    `2 ) 
    <= (p11 
    `2 ) by 
    A13,
    A15,
    EUCLID: 52;
    
              then (p1
    `2 ) 
    =  
    0 by 
    A13,
    A16,
    A40,
    Lm9,
    TOPREAL1: 4;
    
              hence contradiction by
    A13,
    A14,
    A36,
    EUCLID: 53;
    
            end;
    
            then
    
            
    
    A41: 
    {p10}
    <> (( 
    LSeg (p1,p11)) 
    /\ L3) by 
    ZFMISC_1: 31;
    
            ((
    LSeg (p1,p11)) 
    /\ L3) 
    c= (L4 
    /\ L3) by 
    A3,
    Lm27,
    TOPREAL1: 6,
    XBOOLE_1: 26;
    
            then ((
    LSeg (p1,p11)) 
    /\ L3) 
    =  
    {} by 
    A41,
    TOPREAL1: 16,
    ZFMISC_1: 33;
    
            hence (P1
    /\ P2) 
    = (( 
    {p1}
    \/ (L2 
    /\ ( 
    LSeg (p00,p2)))) 
    \/ ((( 
    LSeg (p01,p2)) 
    /\ L3) 
    \/  
    {p2})) by
    A32,
    A39;
    
          end;
    
        end;
    
        now
    
          per cases ;
    
            suppose
    
            
    
    A42: p2 
    = p00; 
    
            then (L2
    /\ ( 
    LSeg (p00,p2))) 
    = (L2 
    /\  
    {p00}) by
    RLTOPSP1: 70;
    
            then (L2
    /\ ( 
    LSeg (p00,p2))) 
    =  
    {} by 
    Lm1,
    Lm13;
    
            hence thesis by
    A33,
    A42,
    ENUMSET1: 1,
    TOPREAL1: 17;
    
          end;
    
            suppose
    
            
    
    A43: p2 
    = p01; 
    
            then ((
    LSeg (p01,p2)) 
    /\ L3) 
    = ( 
    {p01}
    /\ L3) by 
    RLTOPSP1: 70;
    
            then ((
    LSeg (p01,p2)) 
    /\ L3) 
    =  
    {} by 
    Lm1,
    Lm14;
    
            
    
            hence (P1
    /\ P2) 
    = ( 
    {p1}
    \/ ( 
    {p2}
    \/  
    {p2})) by
    A33,
    A43,
    TOPREAL1: 15,
    XBOOLE_1: 4
    
            .=
    {p1, p2} by
    ENUMSET1: 1;
    
          end;
    
            suppose
    
            
    
    A44: p2 
    <> p01 & p2 
    <> p00; 
    
            now
    
              assume p00
    in (( 
    LSeg (p01,p2)) 
    /\ L3); 
    
              then
    
              
    
    A45: p00 
    in ( 
    LSeg (p2,p01)) by 
    XBOOLE_0:def 4;
    
              (p2
    `2 ) 
    <= (p01 
    `2 ) by 
    A30,
    EUCLID: 52;
    
              then
    0  
    = (p2 
    `2 ) by 
    A30,
    A45,
    Lm5,
    TOPREAL1: 4;
    
              hence contradiction by
    A30,
    A44,
    EUCLID: 53;
    
            end;
    
            then
    
            
    
    A46: 
    {p00}
    <> (( 
    LSeg (p01,p2)) 
    /\ L3) by 
    ZFMISC_1: 31;
    
            ((
    LSeg (p01,p2)) 
    /\ L3) 
    c=  
    {p00} by
    A17,
    Lm22,
    TOPREAL1: 6,
    TOPREAL1: 17,
    XBOOLE_1: 26;
    
            then
    
            
    
    A47: (( 
    LSeg (p01,p2)) 
    /\ L3) 
    =  
    {} by 
    A46,
    ZFMISC_1: 33;
    
            now
    
              assume p01
    in (L2 
    /\ ( 
    LSeg (p00,p2))); 
    
              then
    
              
    
    A48: p01 
    in ( 
    LSeg (p00,p2)) by 
    XBOOLE_0:def 4;
    
              (p00
    `2 ) 
    <= (p2 
    `2 ) by 
    A30,
    EUCLID: 52;
    
              then (p01
    `2 ) 
    <= (p2 
    `2 ) by 
    A48,
    TOPREAL1: 4;
    
              then (p2
    `2 ) 
    = 1 by 
    A30,
    Lm7,
    XXREAL_0: 1;
    
              hence contradiction by
    A30,
    A44,
    EUCLID: 53;
    
            end;
    
            then
    
            
    
    A49: 
    {p01}
    <> (L2 
    /\ ( 
    LSeg (p00,p2))) by 
    ZFMISC_1: 31;
    
            (L2
    /\ ( 
    LSeg (p00,p2))) 
    c= (L2 
    /\ L1) by 
    A17,
    Lm20,
    TOPREAL1: 6,
    XBOOLE_1: 26;
    
            then (L2
    /\ ( 
    LSeg (p00,p2))) 
    =  
    {} by 
    A49,
    TOPREAL1: 15,
    ZFMISC_1: 33;
    
            hence thesis by
    A33,
    A47,
    ENUMSET1: 1;
    
          end;
    
        end;
    
        hence thesis;
    
      end;
    
        suppose
    
        
    
    A50: p2 
    in L2; 
    
        then
    
        
    
    A51: ex q st q 
    = p2 & (q 
    `1 ) 
    <= 1 & (q 
    `1 ) 
    >=  
    0 & (q 
    `2 ) 
    = 1 by 
    TOPREAL1: 13;
    
        now
    
          
    
          
    
    A52: (p01 
    `1 ) 
    <= (p2 
    `1 ) by 
    A51,
    EUCLID: 52;
    
          assume
    
          
    
    A53: p11 
    in (( 
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p01,p2))); 
    
          then
    
          
    
    A54: p11 
    in ( 
    LSeg (p10,p1)) by 
    XBOOLE_0:def 4;
    
          p11
    in ( 
    LSeg (p01,p2)) by 
    A53,
    XBOOLE_0:def 4;
    
          then (p11
    `1 ) 
    <= (p2 
    `1 ) by 
    A52,
    TOPREAL1: 3;
    
          then
    
          
    
    A55: 1 
    = (p2 
    `1 ) by 
    A51,
    Lm10,
    XXREAL_0: 1;
    
          (p10
    `2 ) 
    <= (p1 
    `2 ) by 
    A13,
    A16,
    EUCLID: 52;
    
          then (p11
    `2 ) 
    <= (p1 
    `2 ) by 
    A54,
    TOPREAL1: 4;
    
          then 1
    = (p1 
    `2 ) by 
    A13,
    A15,
    Lm11,
    XXREAL_0: 1;
    
          
    
          then p1
    = p11 by 
    A13,
    A14,
    EUCLID: 53
    
          .= p2 by
    A51,
    A55,
    EUCLID: 53;
    
          hence contradiction by
    A1;
    
        end;
    
        then
    
        
    
    A56: 
    {p11}
    <> (( 
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p01,p2))) by 
    ZFMISC_1: 31;
    
        
    
        
    
    A57: L1 
    is_an_arc_of (p00,p01) by 
    Lm5,
    Lm7,
    TOPREAL1: 9;
    
        L3
    is_an_arc_of (p10,p00) by 
    Lm4,
    Lm8,
    TOPREAL1: 9;
    
        then
    
        
    
    A58: (L3 
    \/ L1) 
    is_an_arc_of (p10,p01) by 
    A57,
    TOPREAL1: 2,
    TOPREAL1: 17;
    
        (L1
    /\ L4) 
    =  
    {} by 
    TOPREAL1: 20,
    XBOOLE_0:def 7;
    
        then
    
        
    
    A59: (( 
    LSeg (p1,p11)) 
    /\ L1) 
    =  
    {} by 
    A5,
    XBOOLE_1: 3,
    XBOOLE_1: 26;
    
        take P1 = ((
    LSeg (p1,p11)) 
    \/ ( 
    LSeg (p11,p2))), P2 = (( 
    LSeg (p1,p10)) 
    \/ ((L3 
    \/ L1) 
    \/ ( 
    LSeg (p01,p2)))); 
    
        
    
        
    
    A60: (( 
    LSeg (p1,p11)) 
    \/ ( 
    LSeg (p1,p10))) 
    = L4 by 
    A3,
    TOPREAL1: 5;
    
        p01
    in ( 
    LSeg (p01,p2)) by 
    RLTOPSP1: 68;
    
        then
    
        
    
    A61: (L1 
    /\ ( 
    LSeg (p01,p2))) 
    <>  
    {} by 
    Lm22,
    XBOOLE_0:def 4;
    
        
    
        
    
    A62: p11 
    in ( 
    LSeg (p11,p2)) by 
    RLTOPSP1: 68;
    
        p11
    in ( 
    LSeg (p1,p11)) by 
    RLTOPSP1: 68;
    
        then
    
        
    
    A63: p11 
    in (( 
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p11,p2))) by 
    A62,
    XBOOLE_0:def 4;
    
        
    
        
    
    A64: ( 
    LSeg (p11,p2)) 
    c= L2 by 
    A50,
    Lm26,
    TOPREAL1: 6;
    
        then ((
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p11,p2))) 
    c= (L4 
    /\ L2) by 
    A5,
    XBOOLE_1: 27;
    
        then
    
        
    
    A65: (( 
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p11,p2))) 
    =  
    {p11} by
    A63,
    TOPREAL1: 18,
    ZFMISC_1: 33;
    
        p1
    <> p11 or p11 
    <> p2 by 
    A1;
    
        hence P1
    is_an_arc_of (p1,p2) by 
    A65,
    TOPREAL1: 12;
    
        
    
        
    
    A66: 
    {p1}
    = (( 
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p1,p10))) by 
    A3,
    TOPREAL1: 8;
    
        (L3
    /\ L2) 
    =  
    {} by 
    TOPREAL1: 19,
    XBOOLE_0:def 7;
    
        then
    
        
    
    A67: (( 
    LSeg (p11,p2)) 
    /\ L3) 
    =  
    {} by 
    A64,
    XBOOLE_1: 3,
    XBOOLE_1: 26;
    
        
    
        
    
    A68: ( 
    LSeg (p2,p01)) 
    c= L2 by 
    A50,
    Lm23,
    TOPREAL1: 6;
    
        then
    
        
    
    A69: (L1 
    /\ ( 
    LSeg (p01,p2))) 
    c=  
    {p01} by
    TOPREAL1: 15,
    XBOOLE_1: 27;
    
        
    
        
    
    A70: (L3 
    /\ ( 
    LSeg (p01,p2))) 
    =  
    {} by 
    A68,
    Lm2,
    XBOOLE_1: 3,
    XBOOLE_1: 26;
    
        ((L3
    \/ L1) 
    /\ ( 
    LSeg (p01,p2))) 
    = ((L3 
    /\ ( 
    LSeg (p01,p2))) 
    \/ (L1 
    /\ ( 
    LSeg (p01,p2)))) by 
    XBOOLE_1: 23
    
        .=
    {p01} by
    A70,
    A69,
    A61,
    ZFMISC_1: 33;
    
        then
    
        
    
    A71: ((L3 
    \/ L1) 
    \/ ( 
    LSeg (p01,p2))) 
    is_an_arc_of (p10,p2) by 
    A58,
    TOPREAL1: 10;
    
        
    
        
    
    A72: 
    {p2}
    = (( 
    LSeg (p11,p2)) 
    /\ ( 
    LSeg (p01,p2))) by 
    A50,
    TOPREAL1: 8;
    
        
    
        
    
    A73: (( 
    LSeg (p01,p2)) 
    \/ ( 
    LSeg (p11,p2))) 
    = L2 by 
    A50,
    TOPREAL1: 5;
    
        ((
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p01,p2))) 
    c= (L4 
    /\ L2) by 
    A11,
    A68,
    XBOOLE_1: 27;
    
        then
    
        
    
    A74: (( 
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p01,p2))) 
    =  
    {} by 
    A56,
    TOPREAL1: 18,
    ZFMISC_1: 33;
    
        ((
    LSeg (p1,p10)) 
    /\ ((L3 
    \/ L1) 
    \/ ( 
    LSeg (p01,p2)))) 
    = ((( 
    LSeg (p1,p10)) 
    /\ (L3 
    \/ L1)) 
    \/ (( 
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p01,p2)))) by 
    XBOOLE_1: 23
    
        .= (((
    LSeg (p1,p10)) 
    /\ L3) 
    \/ (( 
    LSeg (p10,p1)) 
    /\ L1)) by 
    A74,
    XBOOLE_1: 23
    
        .=
    {p10} by
    A9,
    A7,
    A12,
    TOPREAL1: 16,
    ZFMISC_1: 33;
    
        hence P2
    is_an_arc_of (p1,p2) by 
    A71,
    TOPREAL1: 11;
    
        
    
        thus (P1
    \/ P2) 
    = (( 
    LSeg (p11,p2)) 
    \/ (( 
    LSeg (p1,p11)) 
    \/ (( 
    LSeg (p1,p10)) 
    \/ ((L3 
    \/ L1) 
    \/ ( 
    LSeg (p01,p2)))))) by 
    XBOOLE_1: 4
    
        .= ((
    LSeg (p11,p2)) 
    \/ (L4 
    \/ ((L3 
    \/ L1) 
    \/ ( 
    LSeg (p01,p2))))) by 
    A60,
    XBOOLE_1: 4
    
        .= ((
    LSeg (p11,p2)) 
    \/ ((L4 
    \/ (L3 
    \/ L1)) 
    \/ ( 
    LSeg (p01,p2)))) by 
    XBOOLE_1: 4
    
        .= ((
    LSeg (p11,p2)) 
    \/ (((L3 
    \/ L4) 
    \/ L1) 
    \/ ( 
    LSeg (p01,p2)))) by 
    XBOOLE_1: 4
    
        .= ((
    LSeg (p11,p2)) 
    \/ ((L3 
    \/ L4) 
    \/ (L1 
    \/ ( 
    LSeg (p01,p2))))) by 
    XBOOLE_1: 4
    
        .= (((L1
    \/ ( 
    LSeg (p01,p2))) 
    \/ ( 
    LSeg (p11,p2))) 
    \/ (L3 
    \/ L4)) by 
    XBOOLE_1: 4
    
        .=
    R^2-unit_square by 
    A73,
    TOPREAL1:def 2,
    XBOOLE_1: 4;
    
        
    
        
    
    A75: (P1 
    /\ P2) 
    = ((( 
    LSeg (p1,p11)) 
    /\ (( 
    LSeg (p1,p10)) 
    \/ ((L3 
    \/ L1) 
    \/ ( 
    LSeg (p01,p2))))) 
    \/ (( 
    LSeg (p11,p2)) 
    /\ (( 
    LSeg (p1,p10)) 
    \/ ((L3 
    \/ L1) 
    \/ ( 
    LSeg (p01,p2)))))) by 
    XBOOLE_1: 23
    
        .= ((((
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p1,p10))) 
    \/ (( 
    LSeg (p1,p11)) 
    /\ ((L3 
    \/ L1) 
    \/ ( 
    LSeg (p01,p2))))) 
    \/ (( 
    LSeg (p11,p2)) 
    /\ (( 
    LSeg (p1,p10)) 
    \/ ((L3 
    \/ L1) 
    \/ ( 
    LSeg (p01,p2)))))) by 
    XBOOLE_1: 23
    
        .= ((
    {p1}
    \/ ((( 
    LSeg (p1,p11)) 
    /\ (L3 
    \/ L1)) 
    \/ (( 
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p01,p2))))) 
    \/ (( 
    LSeg (p11,p2)) 
    /\ (( 
    LSeg (p1,p10)) 
    \/ ((L3 
    \/ L1) 
    \/ ( 
    LSeg (p01,p2)))))) by 
    A66,
    XBOOLE_1: 23
    
        .= ((
    {p1}
    \/ (((( 
    LSeg (p1,p11)) 
    /\ L3) 
    \/ (( 
    LSeg (p1,p11)) 
    /\ L1)) 
    \/ (( 
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p01,p2))))) 
    \/ (( 
    LSeg (p11,p2)) 
    /\ (( 
    LSeg (p1,p10)) 
    \/ ((L3 
    \/ L1) 
    \/ ( 
    LSeg (p01,p2)))))) by 
    XBOOLE_1: 23
    
        .= ((
    {p1}
    \/ ((( 
    LSeg (p1,p11)) 
    /\ L3) 
    \/ (( 
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p01,p2))))) 
    \/ ((( 
    LSeg (p11,p2)) 
    /\ ( 
    LSeg (p1,p10))) 
    \/ (( 
    LSeg (p11,p2)) 
    /\ ((L3 
    \/ L1) 
    \/ ( 
    LSeg (p01,p2)))))) by 
    A59,
    XBOOLE_1: 23
    
        .= ((
    {p1}
    \/ ((( 
    LSeg (p1,p11)) 
    /\ L3) 
    \/ (( 
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p01,p2))))) 
    \/ ((( 
    LSeg (p11,p2)) 
    /\ ( 
    LSeg (p1,p10))) 
    \/ ((( 
    LSeg (p11,p2)) 
    /\ (L3 
    \/ L1)) 
    \/  
    {p2}))) by
    A72,
    XBOOLE_1: 23
    
        .= ((
    {p1}
    \/ ((( 
    LSeg (p1,p11)) 
    /\ L3) 
    \/ (( 
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p01,p2))))) 
    \/ ((( 
    LSeg (p11,p2)) 
    /\ ( 
    LSeg (p1,p10))) 
    \/ (((( 
    LSeg (p11,p2)) 
    /\ L3) 
    \/ (( 
    LSeg (p11,p2)) 
    /\ L1)) 
    \/  
    {p2}))) by
    XBOOLE_1: 23
    
        .= ((
    {p1}
    \/ ((( 
    LSeg (p1,p11)) 
    /\ L3) 
    \/ (( 
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p01,p2))))) 
    \/ ((( 
    LSeg (p11,p2)) 
    /\ ( 
    LSeg (p1,p10))) 
    \/ ((( 
    LSeg (p11,p2)) 
    /\ L1) 
    \/  
    {p2}))) by
    A67;
    
        
    
    A76: 
    
        now
    
          per cases ;
    
            suppose
    
            
    
    A77: p1 
    = p10; 
    
            then
    
            
    
    A78: (( 
    LSeg (p11,p2)) 
    /\ ( 
    LSeg (p1,p10))) 
    = (( 
    LSeg (p11,p2)) 
    /\  
    {p10}) by
    RLTOPSP1: 70;
    
            p10
    in ( 
    LSeg (p11,p2)) implies contradiction by 
    A64,
    Lm7,
    Lm9,
    Lm11,
    TOPREAL1: 4;
    
            then
    
            
    
    A79: (( 
    LSeg (p11,p2)) 
    /\ ( 
    LSeg (p1,p10))) 
    =  
    {} by 
    A78,
    Lm1;
    
            
    
            thus (P1
    /\ P2) 
    = ((( 
    {p1}
    \/  
    {p1})
    \/ (( 
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p01,p2)))) 
    \/ ((( 
    LSeg (p11,p2)) 
    /\ ( 
    LSeg (p1,p10))) 
    \/ ((( 
    LSeg (p11,p2)) 
    /\ L1) 
    \/  
    {p2}))) by
    A75,
    A77,
    TOPREAL1: 16,
    XBOOLE_1: 4
    
            .= ((
    {p1}
    \/ (( 
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p01,p2)))) 
    \/ ((( 
    LSeg (p11,p2)) 
    /\ L1) 
    \/  
    {p2})) by
    A79;
    
          end;
    
            suppose
    
            
    
    A80: p1 
    = p11; 
    
            p11
    in ( 
    LSeg (p11,p2)) by 
    RLTOPSP1: 68;
    
            then
    
            
    
    A81: (( 
    LSeg (p11,p2)) 
    /\ ( 
    LSeg (p1,p10))) 
    <>  
    {} by 
    A80,
    Lm27,
    XBOOLE_0:def 4;
    
            ((
    LSeg (p11,p2)) 
    /\ ( 
    LSeg (p1,p10))) 
    c=  
    {p1} by
    A64,
    A80,
    TOPREAL1: 18,
    XBOOLE_1: 27;
    
            then
    
            
    
    A82: (( 
    LSeg (p11,p2)) 
    /\ ( 
    LSeg (p1,p10))) 
    =  
    {p1} by
    A81,
    ZFMISC_1: 33;
    
            ((
    LSeg (p1,p11)) 
    /\ L3) 
    = ( 
    {p11}
    /\ L3) by 
    A80,
    RLTOPSP1: 70;
    
            then ((
    LSeg (p1,p11)) 
    /\ L3) 
    =  
    {} by 
    Lm1,
    Lm19;
    
            
    
            hence (P1
    /\ P2) 
    = (( 
    {p1}
    \/ ( 
    {p1}
    \/ (( 
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p01,p2))))) 
    \/ ((( 
    LSeg (p11,p2)) 
    /\ L1) 
    \/  
    {p2})) by
    A75,
    A82,
    XBOOLE_1: 4
    
            .= (((
    {p1}
    \/  
    {p1})
    \/ (( 
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p01,p2)))) 
    \/ ((( 
    LSeg (p11,p2)) 
    /\ L1) 
    \/  
    {p2})) by
    XBOOLE_1: 4
    
            .= ((
    {p1}
    \/ (( 
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p01,p2)))) 
    \/ ((( 
    LSeg (p11,p2)) 
    /\ L1) 
    \/  
    {p2}));
    
          end;
    
            suppose
    
            
    
    A83: p1 
    <> p11 & p1 
    <> p10; 
    
            now
    
              assume p11
    in (( 
    LSeg (p11,p2)) 
    /\ ( 
    LSeg (p1,p10))); 
    
              then
    
              
    
    A84: p11 
    in ( 
    LSeg (p10,p1)) by 
    XBOOLE_0:def 4;
    
              (p10
    `2 ) 
    <= (p1 
    `2 ) by 
    A13,
    A16,
    EUCLID: 52;
    
              then (p11
    `2 ) 
    <= (p1 
    `2 ) by 
    A84,
    TOPREAL1: 4;
    
              then 1
    = (p1 
    `2 ) by 
    A13,
    A15,
    Lm11,
    XXREAL_0: 1;
    
              hence contradiction by
    A13,
    A14,
    A83,
    EUCLID: 53;
    
            end;
    
            then
    
            
    
    A85: 
    {p11}
    <> (( 
    LSeg (p11,p2)) 
    /\ ( 
    LSeg (p1,p10))) by 
    ZFMISC_1: 31;
    
            ((
    LSeg (p11,p2)) 
    /\ ( 
    LSeg (p1,p10))) 
    c=  
    {p11} by
    A11,
    A64,
    TOPREAL1: 18,
    XBOOLE_1: 27;
    
            then
    
            
    
    A86: (( 
    LSeg (p11,p2)) 
    /\ ( 
    LSeg (p1,p10))) 
    =  
    {} by 
    A85,
    ZFMISC_1: 33;
    
            now
    
              assume p10
    in (( 
    LSeg (p1,p11)) 
    /\ L3); 
    
              then
    
              
    
    A87: p10 
    in ( 
    LSeg (p1,p11)) by 
    XBOOLE_0:def 4;
    
              (p1
    `2 ) 
    <= (p11 
    `2 ) by 
    A13,
    A15,
    EUCLID: 52;
    
              then (p1
    `2 ) 
    =  
    0 by 
    A13,
    A16,
    A87,
    Lm9,
    TOPREAL1: 4;
    
              hence contradiction by
    A13,
    A14,
    A83,
    EUCLID: 53;
    
            end;
    
            then
    
            
    
    A88: 
    {p10}
    <> (( 
    LSeg (p1,p11)) 
    /\ L3) by 
    ZFMISC_1: 31;
    
            ((
    LSeg (p1,p11)) 
    /\ L3) 
    c= (L4 
    /\ L3) by 
    A3,
    Lm27,
    TOPREAL1: 6,
    XBOOLE_1: 26;
    
            then ((
    LSeg (p1,p11)) 
    /\ L3) 
    =  
    {} by 
    A88,
    TOPREAL1: 16,
    ZFMISC_1: 33;
    
            hence (P1
    /\ P2) 
    = (( 
    {p1}
    \/ (( 
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p01,p2)))) 
    \/ ((( 
    LSeg (p11,p2)) 
    /\ L1) 
    \/  
    {p2})) by
    A75,
    A86;
    
          end;
    
        end;
    
        now
    
          per cases ;
    
            suppose
    
            
    
    A89: p2 
    = p01; 
    
            then
    
            
    
    A90: (( 
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p01,p2))) 
    = (( 
    LSeg (p1,p11)) 
    /\  
    {p01}) by
    RLTOPSP1: 70;
    
             not p01
    in ( 
    LSeg (p1,p11)) by 
    A5,
    Lm6,
    Lm8,
    Lm10,
    TOPREAL1: 3;
    
            then ((
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p01,p2))) 
    =  
    {} by 
    A90,
    Lm1;
    
            hence thesis by
    A76,
    A89,
    ENUMSET1: 1,
    TOPREAL1: 15;
    
          end;
    
            suppose
    
            
    
    A91: p2 
    = p11; 
    
            p11
    in ( 
    LSeg (p1,p11)) by 
    RLTOPSP1: 68;
    
            then
    
            
    
    A92: (( 
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p01,p2))) 
    <>  
    {} by 
    A91,
    Lm26,
    XBOOLE_0:def 4;
    
            ((
    LSeg (p11,p2)) 
    /\ L1) 
    = ( 
    {p11}
    /\ L1) by 
    A91,
    RLTOPSP1: 70;
    
            then
    
            
    
    A93: (( 
    LSeg (p11,p2)) 
    /\ L1) 
    =  
    {} by 
    Lm1,
    Lm18;
    
            ((
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p01,p2))) 
    c= (L4 
    /\ L2) by 
    A5,
    A68,
    XBOOLE_1: 27;
    
            then ((
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p01,p2))) 
    =  
    {p2} by
    A91,
    A92,
    TOPREAL1: 18,
    ZFMISC_1: 33;
    
            
    
            hence (P1
    /\ P2) 
    = ( 
    {p1}
    \/ ( 
    {p2}
    \/  
    {p2})) by
    A76,
    A93,
    XBOOLE_1: 4
    
            .=
    {p1, p2} by
    ENUMSET1: 1;
    
          end;
    
            suppose
    
            
    
    A94: p2 
    <> p11 & p2 
    <> p01; 
    
            now
    
              assume p01
    in (( 
    LSeg (p11,p2)) 
    /\ L1); 
    
              then
    
              
    
    A95: p01 
    in ( 
    LSeg (p2,p11)) by 
    XBOOLE_0:def 4;
    
              (p2
    `1 ) 
    <= (p11 
    `1 ) by 
    A51,
    EUCLID: 52;
    
              then (p2
    `1 ) 
    =  
    0 by 
    A51,
    A95,
    Lm6,
    TOPREAL1: 3;
    
              hence contradiction by
    A51,
    A94,
    EUCLID: 53;
    
            end;
    
            then
    
            
    
    A96: 
    {p01}
    <> (( 
    LSeg (p11,p2)) 
    /\ L1) by 
    ZFMISC_1: 31;
    
            ((
    LSeg (p11,p2)) 
    /\ L1) 
    c= (L2 
    /\ L1) by 
    A50,
    Lm26,
    TOPREAL1: 6,
    XBOOLE_1: 26;
    
            then
    
            
    
    A97: (( 
    LSeg (p11,p2)) 
    /\ L1) 
    =  
    {} by 
    A96,
    TOPREAL1: 15,
    ZFMISC_1: 33;
    
            now
    
              assume p11
    in (( 
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p01,p2))); 
    
              then
    
              
    
    A98: p11 
    in ( 
    LSeg (p01,p2)) by 
    XBOOLE_0:def 4;
    
              (p01
    `1 ) 
    <= (p2 
    `1 ) by 
    A51,
    EUCLID: 52;
    
              then (p11
    `1 ) 
    <= (p2 
    `1 ) by 
    A98,
    TOPREAL1: 3;
    
              then 1
    = (p2 
    `1 ) by 
    A51,
    Lm10,
    XXREAL_0: 1;
    
              hence contradiction by
    A51,
    A94,
    EUCLID: 53;
    
            end;
    
            then
    
            
    
    A99: 
    {p11}
    <> (( 
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p01,p2))) by 
    ZFMISC_1: 31;
    
            ((
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p01,p2))) 
    c= (L4 
    /\ L2) by 
    A5,
    A68,
    XBOOLE_1: 27;
    
            then ((
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p01,p2))) 
    =  
    {} by 
    A99,
    TOPREAL1: 18,
    ZFMISC_1: 33;
    
            hence thesis by
    A76,
    A97,
    ENUMSET1: 1;
    
          end;
    
        end;
    
        hence thesis;
    
      end;
    
        suppose
    
        
    
    A100: p2 
    in L3; 
    
        then
    
        
    
    A101: ex q st q 
    = p2 & (q 
    `1 ) 
    <= 1 & (q 
    `1 ) 
    >=  
    0 & (q 
    `2 ) 
    =  
    0 by 
    TOPREAL1: 13;
    
        now
    
          
    
          
    
    A102: (p00 
    `1 ) 
    <= (p2 
    `1 ) by 
    A101,
    EUCLID: 52;
    
          assume
    
          
    
    A103: p10 
    in (( 
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p00,p2))); 
    
          then
    
          
    
    A104: p10 
    in ( 
    LSeg (p1,p11)) by 
    XBOOLE_0:def 4;
    
          p10
    in ( 
    LSeg (p00,p2)) by 
    A103,
    XBOOLE_0:def 4;
    
          then (p10
    `1 ) 
    <= (p2 
    `1 ) by 
    A102,
    TOPREAL1: 3;
    
          then
    
          
    
    A105: 1 
    = (p2 
    `1 ) by 
    A101,
    Lm8,
    XXREAL_0: 1;
    
          (p1
    `2 ) 
    <= (p11 
    `2 ) by 
    A13,
    A15,
    EUCLID: 52;
    
          then
    0  
    = (p1 
    `2 ) by 
    A13,
    A16,
    A104,
    Lm9,
    TOPREAL1: 4;
    
          then p1
    = p10 by 
    A13,
    A14,
    EUCLID: 53;
    
          hence contradiction by
    A1,
    A101,
    A105,
    EUCLID: 53;
    
        end;
    
        then
    
        
    
    A106: 
    {p10}
    <> (( 
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p00,p2))) by 
    ZFMISC_1: 31;
    
        
    
        
    
    A107: L1 
    is_an_arc_of (p01,p00) by 
    Lm5,
    Lm7,
    TOPREAL1: 9;
    
        L2
    is_an_arc_of (p11,p01) by 
    Lm6,
    Lm10,
    TOPREAL1: 9;
    
        then
    
        
    
    A108: (L2 
    \/ L1) 
    is_an_arc_of (p11,p00) by 
    A107,
    TOPREAL1: 2,
    TOPREAL1: 15;
    
        take P1 = ((
    LSeg (p1,p10)) 
    \/ ( 
    LSeg (p10,p2))), P2 = (( 
    LSeg (p1,p11)) 
    \/ ((L2 
    \/ L1) 
    \/ ( 
    LSeg (p00,p2)))); 
    
        
    
        
    
    A109: (( 
    LSeg (p1,p10)) 
    \/ ( 
    LSeg (p1,p11))) 
    = L4 by 
    A3,
    TOPREAL1: 5;
    
        p00
    in ( 
    LSeg (p00,p2)) by 
    RLTOPSP1: 68;
    
        then
    
        
    
    A110: (L1 
    /\ ( 
    LSeg (p00,p2))) 
    <>  
    {} by 
    Lm20,
    XBOOLE_0:def 4;
    
        
    
        
    
    A111: p10 
    in ( 
    LSeg (p10,p2)) by 
    RLTOPSP1: 68;
    
        p10
    in ( 
    LSeg (p1,p10)) by 
    RLTOPSP1: 68;
    
        then
    
        
    
    A112: (( 
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p10,p2))) 
    <>  
    {} by 
    A111,
    XBOOLE_0:def 4;
    
        
    
        
    
    A113: ( 
    LSeg (p2,p10)) 
    c= L3 by 
    A100,
    Lm24,
    TOPREAL1: 6;
    
        then ((
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p10,p2))) 
    c= (L4 
    /\ L3) by 
    A11,
    XBOOLE_1: 27;
    
        then
    
        
    
    A114: (( 
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p10,p2))) 
    =  
    {p10} by
    A112,
    TOPREAL1: 16,
    ZFMISC_1: 33;
    
        p1
    <> p10 or p2 
    <> p10 by 
    A1;
    
        hence P1
    is_an_arc_of (p1,p2) by 
    A114,
    TOPREAL1: 12;
    
        
    
        
    
    A115: (( 
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p1,p11))) 
    =  
    {p1} by
    A3,
    TOPREAL1: 8;
    
        (L3
    /\ L2) 
    =  
    {} by 
    TOPREAL1: 19,
    XBOOLE_0:def 7;
    
        then
    
        
    
    A116: (( 
    LSeg (p10,p2)) 
    /\ L2) 
    =  
    {} by 
    A113,
    XBOOLE_1: 3,
    XBOOLE_1: 26;
    
        
    
        
    
    A117: ( 
    LSeg (p2,p00)) 
    c= L3 by 
    A100,
    Lm21,
    TOPREAL1: 6;
    
        then
    
        
    
    A118: (L1 
    /\ ( 
    LSeg (p00,p2))) 
    c=  
    {p00} by
    TOPREAL1: 17,
    XBOOLE_1: 27;
    
        
    
        
    
    A119: (L2 
    /\ ( 
    LSeg (p00,p2))) 
    =  
    {} by 
    A117,
    Lm2,
    XBOOLE_1: 3,
    XBOOLE_1: 26;
    
        ((L2
    \/ L1) 
    /\ ( 
    LSeg (p00,p2))) 
    = ((L2 
    /\ ( 
    LSeg (p00,p2))) 
    \/ (L1 
    /\ ( 
    LSeg (p00,p2)))) by 
    XBOOLE_1: 23
    
        .=
    {p00} by
    A119,
    A118,
    A110,
    ZFMISC_1: 33;
    
        then
    
        
    
    A120: ((L2 
    \/ L1) 
    \/ ( 
    LSeg (p00,p2))) 
    is_an_arc_of (p11,p2) by 
    A108,
    TOPREAL1: 10;
    
        
    
        
    
    A121: (( 
    LSeg (p10,p2)) 
    /\ ( 
    LSeg (p00,p2))) 
    =  
    {p2} by
    A100,
    TOPREAL1: 8;
    
        
    
        
    
    A122: (( 
    LSeg (p00,p2)) 
    \/ ( 
    LSeg (p10,p2))) 
    = L3 by 
    A100,
    TOPREAL1: 5;
    
        ((
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p00,p2))) 
    c= (L4 
    /\ L3) by 
    A5,
    A117,
    XBOOLE_1: 27;
    
        then
    
        
    
    A123: (( 
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p00,p2))) 
    =  
    {} by 
    A106,
    TOPREAL1: 16,
    ZFMISC_1: 33;
    
        ((
    LSeg (p1,p11)) 
    /\ ((L2 
    \/ L1) 
    \/ ( 
    LSeg (p00,p2)))) 
    = ((( 
    LSeg (p1,p11)) 
    /\ (L2 
    \/ L1)) 
    \/ (( 
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p00,p2)))) by 
    XBOOLE_1: 23
    
        .= (((
    LSeg (p1,p11)) 
    /\ L2) 
    \/ (( 
    LSeg (p1,p11)) 
    /\ L1)) by 
    A123,
    XBOOLE_1: 23
    
        .=
    {p11} by
    A8,
    A6,
    A10,
    TOPREAL1: 18,
    ZFMISC_1: 33;
    
        hence P2
    is_an_arc_of (p1,p2) by 
    A120,
    TOPREAL1: 11;
    
        
    
        thus (P1
    \/ P2) 
    = (( 
    LSeg (p10,p2)) 
    \/ (( 
    LSeg (p1,p10)) 
    \/ (( 
    LSeg (p1,p11)) 
    \/ ((L1 
    \/ L2) 
    \/ ( 
    LSeg (p00,p2)))))) by 
    XBOOLE_1: 4
    
        .= ((
    LSeg (p10,p2)) 
    \/ (L4 
    \/ ((L1 
    \/ L2) 
    \/ ( 
    LSeg (p00,p2))))) by 
    A109,
    XBOOLE_1: 4
    
        .= ((((L1
    \/ L2) 
    \/ L4) 
    \/ ( 
    LSeg (p00,p2))) 
    \/ ( 
    LSeg (p10,p2))) by 
    XBOOLE_1: 4
    
        .= (((L1
    \/ L2) 
    \/ L4) 
    \/ L3) by 
    A122,
    XBOOLE_1: 4
    
        .=
    R^2-unit_square by 
    TOPREAL1:def 2,
    XBOOLE_1: 4;
    
        
    
        
    
    A124: (P1 
    /\ P2) 
    = ((( 
    LSeg (p1,p10)) 
    /\ (( 
    LSeg (p1,p11)) 
    \/ ((L2 
    \/ L1) 
    \/ ( 
    LSeg (p00,p2))))) 
    \/ (( 
    LSeg (p10,p2)) 
    /\ (( 
    LSeg (p1,p11)) 
    \/ ((L2 
    \/ L1) 
    \/ ( 
    LSeg (p00,p2)))))) by 
    XBOOLE_1: 23
    
        .= ((((
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p1,p11))) 
    \/ (( 
    LSeg (p1,p10)) 
    /\ ((L2 
    \/ L1) 
    \/ ( 
    LSeg (p00,p2))))) 
    \/ (( 
    LSeg (p10,p2)) 
    /\ (( 
    LSeg (p1,p11)) 
    \/ ((L2 
    \/ L1) 
    \/ ( 
    LSeg (p00,p2)))))) by 
    XBOOLE_1: 23
    
        .= ((
    {p1}
    \/ ((( 
    LSeg (p1,p10)) 
    /\ (L2 
    \/ L1)) 
    \/ (( 
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p00,p2))))) 
    \/ (( 
    LSeg (p10,p2)) 
    /\ (( 
    LSeg (p1,p11)) 
    \/ ((L2 
    \/ L1) 
    \/ ( 
    LSeg (p00,p2)))))) by 
    A115,
    XBOOLE_1: 23
    
        .= ((
    {p1}
    \/ (((( 
    LSeg (p1,p10)) 
    /\ L2) 
    \/ (( 
    LSeg (p10,p1)) 
    /\ L1)) 
    \/ (( 
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p00,p2))))) 
    \/ (( 
    LSeg (p10,p2)) 
    /\ (( 
    LSeg (p1,p11)) 
    \/ ((L2 
    \/ L1) 
    \/ ( 
    LSeg (p00,p2)))))) by 
    XBOOLE_1: 23
    
        .= ((
    {p1}
    \/ ((( 
    LSeg (p1,p10)) 
    /\ L2) 
    \/ (( 
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p00,p2))))) 
    \/ ((( 
    LSeg (p10,p2)) 
    /\ ( 
    LSeg (p1,p11))) 
    \/ (( 
    LSeg (p10,p2)) 
    /\ ((L2 
    \/ L1) 
    \/ ( 
    LSeg (p00,p2)))))) by 
    A12,
    XBOOLE_1: 23
    
        .= ((
    {p1}
    \/ ((( 
    LSeg (p1,p10)) 
    /\ L2) 
    \/ (( 
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p00,p2))))) 
    \/ ((( 
    LSeg (p10,p2)) 
    /\ ( 
    LSeg (p1,p11))) 
    \/ ((( 
    LSeg (p10,p2)) 
    /\ (L2 
    \/ L1)) 
    \/  
    {p2}))) by
    A121,
    XBOOLE_1: 23
    
        .= ((
    {p1}
    \/ ((( 
    LSeg (p1,p10)) 
    /\ L2) 
    \/ (( 
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p00,p2))))) 
    \/ ((( 
    LSeg (p10,p2)) 
    /\ ( 
    LSeg (p1,p11))) 
    \/ (((( 
    LSeg (p10,p2)) 
    /\ L2) 
    \/ (( 
    LSeg (p10,p2)) 
    /\ L1)) 
    \/  
    {p2}))) by
    XBOOLE_1: 23
    
        .= ((
    {p1}
    \/ ((( 
    LSeg (p1,p10)) 
    /\ L2) 
    \/ (( 
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p00,p2))))) 
    \/ ((( 
    LSeg (p10,p2)) 
    /\ ( 
    LSeg (p1,p11))) 
    \/ ((( 
    LSeg (p10,p2)) 
    /\ L1) 
    \/  
    {p2}))) by
    A116;
    
        
    
    A125: 
    
        now
    
          per cases ;
    
            suppose
    
            
    
    A126: p1 
    = p10; 
    
            p10
    in ( 
    LSeg (p10,p2)) by 
    RLTOPSP1: 68;
    
            then
    
            
    
    A127: (( 
    LSeg (p10,p2)) 
    /\ ( 
    LSeg (p1,p11))) 
    <>  
    {} by 
    A126,
    Lm25,
    XBOOLE_0:def 4;
    
            ((
    LSeg (p10,p2)) 
    /\ ( 
    LSeg (p1,p11))) 
    c=  
    {p1} by
    A113,
    A126,
    TOPREAL1: 16,
    XBOOLE_1: 27;
    
            then
    
            
    
    A128: (( 
    LSeg (p10,p2)) 
    /\ ( 
    LSeg (p1,p11))) 
    =  
    {p1} by
    A127,
    ZFMISC_1: 33;
    
            ((
    LSeg (p1,p10)) 
    /\ L2) 
    = ( 
    {p10}
    /\ L2) by 
    A126,
    RLTOPSP1: 70;
    
            then ((
    LSeg (p1,p10)) 
    /\ L2) 
    =  
    {} by 
    Lm1,
    Lm17;
    
            
    
            hence (P1
    /\ P2) 
    = (( 
    {p1}
    \/ ( 
    {p1}
    \/ (( 
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p00,p2))))) 
    \/ ((( 
    LSeg (p10,p2)) 
    /\ L1) 
    \/  
    {p2})) by
    A124,
    A128,
    XBOOLE_1: 4
    
            .= (((
    {p1}
    \/  
    {p1})
    \/ (( 
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p00,p2)))) 
    \/ ((( 
    LSeg (p10,p2)) 
    /\ L1) 
    \/  
    {p2})) by
    XBOOLE_1: 4
    
            .= ((
    {p1}
    \/ (( 
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p00,p2)))) 
    \/ ((( 
    LSeg (p10,p2)) 
    /\ L1) 
    \/  
    {p2}));
    
          end;
    
            suppose
    
            
    
    A129: p1 
    = p11; 
    
            then
    
            
    
    A130: (( 
    LSeg (p10,p2)) 
    /\ ( 
    LSeg (p1,p11))) 
    = (( 
    LSeg (p10,p2)) 
    /\  
    {p11}) by
    RLTOPSP1: 70;
    
             not p11
    in ( 
    LSeg (p10,p2)) by 
    A113,
    Lm5,
    Lm9,
    Lm11,
    TOPREAL1: 4;
    
            then ((
    LSeg (p10,p2)) 
    /\ ( 
    LSeg (p1,p11))) 
    =  
    {} by 
    A130,
    Lm1;
    
            
    
            hence (P1
    /\ P2) 
    = ((( 
    {p1}
    \/  
    {p1})
    \/ (( 
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p00,p2)))) 
    \/ ((( 
    LSeg (p10,p2)) 
    /\ L1) 
    \/  
    {p2})) by
    A124,
    A129,
    TOPREAL1: 18,
    XBOOLE_1: 4
    
            .= ((
    {p1}
    \/ (( 
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p00,p2)))) 
    \/ ((( 
    LSeg (p10,p2)) 
    /\ L1) 
    \/  
    {p2}));
    
          end;
    
            suppose
    
            
    
    A131: p1 
    <> p11 & p1 
    <> p10; 
    
            now
    
              assume p10
    in (( 
    LSeg (p10,p2)) 
    /\ ( 
    LSeg (p1,p11))); 
    
              then
    
              
    
    A132: p10 
    in ( 
    LSeg (p1,p11)) by 
    XBOOLE_0:def 4;
    
              (p1
    `2 ) 
    <= (p11 
    `2 ) by 
    A13,
    A15,
    EUCLID: 52;
    
              then (p1
    `2 ) 
    =  
    0 by 
    A13,
    A16,
    A132,
    Lm9,
    TOPREAL1: 4;
    
              hence contradiction by
    A13,
    A14,
    A131,
    EUCLID: 53;
    
            end;
    
            then
    
            
    
    A133: 
    {p10}
    <> (( 
    LSeg (p10,p2)) 
    /\ ( 
    LSeg (p1,p11))) by 
    ZFMISC_1: 31;
    
            ((
    LSeg (p10,p2)) 
    /\ ( 
    LSeg (p1,p11))) 
    c=  
    {p10} by
    A5,
    A113,
    TOPREAL1: 16,
    XBOOLE_1: 27;
    
            then
    
            
    
    A134: (( 
    LSeg (p10,p2)) 
    /\ ( 
    LSeg (p1,p11))) 
    =  
    {} by 
    A133,
    ZFMISC_1: 33;
    
            now
    
              assume p11
    in (( 
    LSeg (p1,p10)) 
    /\ L2); 
    
              then
    
              
    
    A135: p11 
    in ( 
    LSeg (p10,p1)) by 
    XBOOLE_0:def 4;
    
              (p10
    `2 ) 
    <= (p1 
    `2 ) by 
    A13,
    A16,
    EUCLID: 52;
    
              then (p11
    `2 ) 
    <= (p1 
    `2 ) by 
    A135,
    TOPREAL1: 4;
    
              then (p1
    `2 ) 
    = 1 by 
    A13,
    A15,
    Lm11,
    XXREAL_0: 1;
    
              hence contradiction by
    A13,
    A14,
    A131,
    EUCLID: 53;
    
            end;
    
            then
    
            
    
    A136: (( 
    LSeg (p1,p10)) 
    /\ L2) 
    <>  
    {p11} by
    ZFMISC_1: 31;
    
            ((
    LSeg (p1,p10)) 
    /\ L2) 
    c= (L4 
    /\ L2) by 
    A3,
    Lm25,
    TOPREAL1: 6,
    XBOOLE_1: 26;
    
            then ((
    LSeg (p1,p10)) 
    /\ L2) 
    =  
    {} by 
    A136,
    TOPREAL1: 18,
    ZFMISC_1: 33;
    
            hence (P1
    /\ P2) 
    = (( 
    {p1}
    \/ (( 
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p00,p2)))) 
    \/ ((( 
    LSeg (p10,p2)) 
    /\ L1) 
    \/  
    {p2})) by
    A124,
    A134;
    
          end;
    
        end;
    
        now
    
          per cases ;
    
            suppose
    
            
    
    A137: p2 
    = p00; 
    
            then
    
            
    
    A138: (( 
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p00,p2))) 
    = (( 
    LSeg (p1,p10)) 
    /\  
    {p00}) by
    RLTOPSP1: 70;
    
             not p00
    in ( 
    LSeg (p1,p10)) by 
    A11,
    Lm4,
    Lm8,
    Lm10,
    TOPREAL1: 3;
    
            then ((
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p00,p2))) 
    =  
    {} by 
    A138,
    Lm1;
    
            hence thesis by
    A125,
    A137,
    ENUMSET1: 1,
    TOPREAL1: 17;
    
          end;
    
            suppose
    
            
    
    A139: p2 
    = p10; 
    
            p10
    in ( 
    LSeg (p1,p10)) by 
    RLTOPSP1: 68;
    
            then
    
            
    
    A140: (( 
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p00,p2))) 
    <>  
    {} by 
    A139,
    Lm24,
    XBOOLE_0:def 4;
    
            ((
    LSeg (p10,p2)) 
    /\ L1) 
    = ( 
    {p10}
    /\ L1) by 
    A139,
    RLTOPSP1: 70;
    
            then
    
            
    
    A141: (( 
    LSeg (p10,p2)) 
    /\ L1) 
    =  
    {} by 
    Lm1,
    Lm16;
    
            ((
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p00,p2))) 
    c= (L4 
    /\ L3) by 
    A11,
    A117,
    XBOOLE_1: 27;
    
            then ((
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p00,p2))) 
    =  
    {p2} by
    A139,
    A140,
    TOPREAL1: 16,
    ZFMISC_1: 33;
    
            
    
            hence (P1
    /\ P2) 
    = ( 
    {p1}
    \/ ( 
    {p2}
    \/  
    {p2})) by
    A125,
    A141,
    XBOOLE_1: 4
    
            .=
    {p1, p2} by
    ENUMSET1: 1;
    
          end;
    
            suppose
    
            
    
    A142: p2 
    <> p10 & p2 
    <> p00; 
    
            now
    
              assume p00
    in (( 
    LSeg (p10,p2)) 
    /\ L1); 
    
              then
    
              
    
    A143: p00 
    in ( 
    LSeg (p2,p10)) by 
    XBOOLE_0:def 4;
    
              (p2
    `1 ) 
    <= (p10 
    `1 ) by 
    A101,
    EUCLID: 52;
    
              then (p2
    `1 ) 
    =  
    0 by 
    A101,
    A143,
    Lm4,
    TOPREAL1: 3;
    
              hence contradiction by
    A101,
    A142,
    EUCLID: 53;
    
            end;
    
            then
    
            
    
    A144: 
    {p00}
    <> (( 
    LSeg (p10,p2)) 
    /\ L1) by 
    ZFMISC_1: 31;
    
            ((
    LSeg (p10,p2)) 
    /\ L1) 
    c= (L3 
    /\ L1) by 
    A100,
    Lm24,
    TOPREAL1: 6,
    XBOOLE_1: 26;
    
            then
    
            
    
    A145: (( 
    LSeg (p10,p2)) 
    /\ L1) 
    =  
    {} by 
    A144,
    TOPREAL1: 17,
    ZFMISC_1: 33;
    
            now
    
              assume p10
    in (( 
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p00,p2))); 
    
              then
    
              
    
    A146: p10 
    in ( 
    LSeg (p00,p2)) by 
    XBOOLE_0:def 4;
    
              (p00
    `1 ) 
    <= (p2 
    `1 ) by 
    A101,
    EUCLID: 52;
    
              then (p10
    `1 ) 
    <= (p2 
    `1 ) by 
    A146,
    TOPREAL1: 3;
    
              then (p2
    `1 ) 
    = 1 by 
    A101,
    Lm8,
    XXREAL_0: 1;
    
              hence contradiction by
    A101,
    A142,
    EUCLID: 53;
    
            end;
    
            then
    
            
    
    A147: 
    {p10}
    <> (( 
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p00,p2))) by 
    ZFMISC_1: 31;
    
            ((
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p00,p2))) 
    c= (L4 
    /\ L3) by 
    A11,
    A117,
    XBOOLE_1: 27;
    
            then ((
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p00,p2))) 
    =  
    {} by 
    A147,
    TOPREAL1: 16,
    ZFMISC_1: 33;
    
            hence thesis by
    A125,
    A145,
    ENUMSET1: 1;
    
          end;
    
        end;
    
        hence thesis;
    
      end;
    
        suppose
    
        
    
    A148: p2 
    in L4; 
    
        
    
        
    
    A149: p 
    =  
    |[(p
    `1 ), (p 
    `2 )]| by 
    EUCLID: 53;
    
        
    
        
    
    A150: ( 
    LSeg (p1,p2)) 
    c= L4 by 
    A3,
    A148,
    TOPREAL1: 6;
    
        consider q such that
    
        
    
    A151: q 
    = p2 and 
    
        
    
    A152: (q 
    `1 ) 
    = 1 and 
    
        
    
    A153: (q 
    `2 ) 
    <= 1 and 
    
        
    
    A154: (q 
    `2 ) 
    >=  
    0 by 
    A148,
    TOPREAL1: 13;
    
        
    
        
    
    A155: q 
    =  
    |[(q
    `1 ), (q 
    `2 )]| by 
    EUCLID: 53;
    
        now
    
          per cases by
    A1,
    A13,
    A14,
    A151,
    A152,
    A149,
    A155,
    XXREAL_0: 1;
    
            suppose
    
            
    
    A156: (p 
    `2 ) 
    < (q 
    `2 ); 
    
            
    
            
    
    A157: (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p11,p2))) 
    c=  
    {p2}
    
            proof
    
              let a be
    object;
    
              assume
    
              
    
    A158: a 
    in (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p11,p2))); 
    
              then
    
              reconsider p = a as
    Point of ( 
    TOP-REAL 2); 
    
              
    
              
    
    A159: p 
    in ( 
    LSeg (p2,p11)) by 
    A158,
    XBOOLE_0:def 4;
    
              (p2
    `2 ) 
    <= (p11 
    `2 ) by 
    A151,
    A153,
    EUCLID: 52;
    
              then
    
              
    
    A160: (p2 
    `2 ) 
    <= (p 
    `2 ) by 
    A159,
    TOPREAL1: 4;
    
              
    
              
    
    A161: p 
    in ( 
    LSeg (p1,p2)) by 
    A158,
    XBOOLE_0:def 4;
    
              then
    
              
    
    A162: (p1 
    `1 ) 
    <= (p 
    `1 ) by 
    A13,
    A14,
    A151,
    A152,
    TOPREAL1: 3;
    
              (p
    `2 ) 
    <= (p2 
    `2 ) by 
    A13,
    A151,
    A156,
    A161,
    TOPREAL1: 4;
    
              then
    
              
    
    A163: (p2 
    `2 ) 
    = (p 
    `2 ) by 
    A160,
    XXREAL_0: 1;
    
              (p
    `1 ) 
    <= (p2 
    `1 ) by 
    A13,
    A14,
    A151,
    A152,
    A161,
    TOPREAL1: 3;
    
              then (p
    `1 ) 
    = 1 by 
    A13,
    A14,
    A151,
    A152,
    A162,
    XXREAL_0: 1;
    
              
    
              then p
    =  
    |[1, (p2
    `2 )]| by 
    A163,
    EUCLID: 53
    
              .= p2 by
    A151,
    A152,
    EUCLID: 53;
    
              hence thesis by
    TARSKI:def 1;
    
            end;
    
            p10
    in ( 
    LSeg (p1,p10)) by 
    RLTOPSP1: 68;
    
            then
    
            
    
    A164: (( 
    LSeg (p1,p10)) 
    /\ L3) 
    <>  
    {} by 
    Lm24,
    XBOOLE_0:def 4;
    
            
    
    A165: 
    
            now
    
              set a = the
    Element of (( 
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p11,p2))); 
    
              assume
    
              
    
    A166: (( 
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p11,p2))) 
    <>  
    {} ; 
    
              then
    
              reconsider p = a as
    Point of ( 
    TOP-REAL 2) by 
    TARSKI:def 3;
    
              
    
              
    
    A167: p 
    in ( 
    LSeg (p10,p1)) by 
    A166,
    XBOOLE_0:def 4;
    
              
    
              
    
    A168: p 
    in ( 
    LSeg (p2,p11)) by 
    A166,
    XBOOLE_0:def 4;
    
              (p2
    `2 ) 
    <= (p11 
    `2 ) by 
    A151,
    A153,
    EUCLID: 52;
    
              then
    
              
    
    A169: (p2 
    `2 ) 
    <= (p 
    `2 ) by 
    A168,
    TOPREAL1: 4;
    
              (p10
    `2 ) 
    <= (p1 
    `2 ) by 
    A13,
    A16,
    EUCLID: 52;
    
              then (p
    `2 ) 
    <= (p1 
    `2 ) by 
    A167,
    TOPREAL1: 4;
    
              hence contradiction by
    A13,
    A151,
    A156,
    A169,
    XXREAL_0: 2;
    
            end;
    
            
    
            
    
    A170: ((L3 
    \/ L1) 
    /\ L2) 
    = ((L3 
    /\ L2) 
    \/ (L1 
    /\ L2)) by 
    XBOOLE_1: 23
    
            .=
    {p01} by
    Lm2,
    TOPREAL1: 15;
    
            (L3
    \/ L1) 
    is_an_arc_of (p10,p01) by 
    Lm4,
    Lm8,
    TOPREAL1: 9,
    TOPREAL1: 10,
    TOPREAL1: 17;
    
            then
    
            
    
    A171: ((L3 
    \/ L1) 
    \/ L2) 
    is_an_arc_of (p10,p11) by 
    A170,
    TOPREAL1: 10;
    
            now
    
              assume p11
    in (( 
    LSeg (p1,p10)) 
    /\ L2); 
    
              then
    
              
    
    A172: p11 
    in ( 
    LSeg (p10,p1)) by 
    XBOOLE_0:def 4;
    
              (p10
    `2 ) 
    <= (p1 
    `2 ) by 
    A13,
    A16,
    EUCLID: 52;
    
              then (p11
    `2 ) 
    <= (p1 
    `2 ) by 
    A172,
    TOPREAL1: 4;
    
              hence contradiction by
    A13,
    A15,
    A153,
    A156,
    Lm11,
    XXREAL_0: 1;
    
            end;
    
            then
    
            
    
    A173: 
    {p11}
    <> (( 
    LSeg (p1,p10)) 
    /\ L2) by 
    ZFMISC_1: 31;
    
            ((
    LSeg (p1,p10)) 
    /\ L2) 
    c= (L4 
    /\ L2) by 
    A3,
    Lm25,
    TOPREAL1: 6,
    XBOOLE_1: 26;
    
            then
    
            
    
    A174: (( 
    LSeg (p1,p10)) 
    /\ L2) 
    =  
    {} by 
    A173,
    TOPREAL1: 18,
    ZFMISC_1: 33;
    
            (L1
    /\ L4) 
    =  
    {} by 
    TOPREAL1: 20,
    XBOOLE_0:def 7;
    
            then
    
            
    
    A175: (( 
    LSeg (p1,p10)) 
    /\ L1) 
    =  
    {} by 
    A11,
    XBOOLE_1: 3,
    XBOOLE_1: 26;
    
            now
    
              assume p10
    in (L3 
    /\ ( 
    LSeg (p11,p2))); 
    
              then
    
              
    
    A176: p10 
    in ( 
    LSeg (p2,p11)) by 
    XBOOLE_0:def 4;
    
              (p2
    `2 ) 
    <= (p11 
    `2 ) by 
    A151,
    A153,
    EUCLID: 52;
    
              hence contradiction by
    A16,
    A151,
    A156,
    A176,
    Lm9,
    TOPREAL1: 4;
    
            end;
    
            then
    
            
    
    A177: 
    {p10}
    <> (L3 
    /\ ( 
    LSeg (p11,p2))) by 
    ZFMISC_1: 31;
    
            (L3
    /\ ( 
    LSeg (p11,p2))) 
    c=  
    {p10} by
    A148,
    Lm27,
    TOPREAL1: 6,
    TOPREAL1: 16,
    XBOOLE_1: 26;
    
            then
    
            
    
    A178: (L3 
    /\ ( 
    LSeg (p11,p2))) 
    =  
    {} by 
    A177,
    ZFMISC_1: 33;
    
            (L1
    /\ L4) 
    =  
    {} by 
    TOPREAL1: 20,
    XBOOLE_0:def 7;
    
            then
    
            
    
    A179: (( 
    LSeg (p1,p2)) 
    /\ L1) 
    =  
    {} by 
    A150,
    XBOOLE_1: 3,
    XBOOLE_1: 26;
    
            
    
            
    
    A180: (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p1,p10))) 
    c=  
    {p1}
    
            proof
    
              let a be
    object;
    
              assume
    
              
    
    A181: a 
    in (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p1,p10))); 
    
              then
    
              reconsider p = a as
    Point of ( 
    TOP-REAL 2); 
    
              
    
              
    
    A182: p 
    in ( 
    LSeg (p10,p1)) by 
    A181,
    XBOOLE_0:def 4;
    
              (p10
    `2 ) 
    <= (p1 
    `2 ) by 
    A13,
    A16,
    EUCLID: 52;
    
              then
    
              
    
    A183: (p 
    `2 ) 
    <= (p1 
    `2 ) by 
    A182,
    TOPREAL1: 4;
    
              
    
              
    
    A184: p 
    in ( 
    LSeg (p1,p2)) by 
    A181,
    XBOOLE_0:def 4;
    
              then
    
              
    
    A185: (p1 
    `1 ) 
    <= (p 
    `1 ) by 
    A13,
    A14,
    A151,
    A152,
    TOPREAL1: 3;
    
              (p1
    `2 ) 
    <= (p 
    `2 ) by 
    A13,
    A151,
    A156,
    A184,
    TOPREAL1: 4;
    
              then
    
              
    
    A186: (p1 
    `2 ) 
    = (p 
    `2 ) by 
    A183,
    XXREAL_0: 1;
    
              (p
    `1 ) 
    <= (p2 
    `1 ) by 
    A13,
    A14,
    A151,
    A152,
    A184,
    TOPREAL1: 3;
    
              then (p
    `1 ) 
    = 1 by 
    A13,
    A14,
    A151,
    A152,
    A185,
    XXREAL_0: 1;
    
              
    
              then p
    =  
    |[1, (p1
    `2 )]| by 
    A186,
    EUCLID: 53
    
              .= p1 by
    A13,
    A14,
    EUCLID: 53;
    
              hence thesis by
    TARSKI:def 1;
    
            end;
    
            
    
            
    
    A187: (( 
    LSeg (p1,p10)) 
    /\ L3) 
    c= (L4 
    /\ L3) by 
    A3,
    Lm25,
    TOPREAL1: 6,
    XBOOLE_1: 26;
    
            p11
    in ( 
    LSeg (p11,p2)) by 
    RLTOPSP1: 68;
    
            then
    
            
    
    A188: (L2 
    /\ ( 
    LSeg (p11,p2))) 
    <>  
    {} by 
    Lm26,
    XBOOLE_0:def 4;
    
            (L2
    /\ ( 
    LSeg (p11,p2))) 
    c=  
    {p11} by
    A148,
    Lm27,
    TOPREAL1: 6,
    TOPREAL1: 18,
    XBOOLE_1: 26;
    
            then
    
            
    
    A189: (L2 
    /\ ( 
    LSeg (p11,p2))) 
    =  
    {p11} by
    A188,
    ZFMISC_1: 33;
    
            take P1 = (
    LSeg (p1,p2)), P2 = (( 
    LSeg (p1,p10)) 
    \/ (((L3 
    \/ L1) 
    \/ L2) 
    \/ ( 
    LSeg (p11,p2)))); 
    
            
    
            
    
    A190: p1 
    in ( 
    LSeg (p1,p10)) by 
    RLTOPSP1: 68;
    
            thus P1
    is_an_arc_of (p1,p2) by 
    A1,
    TOPREAL1: 9;
    
            
    
            
    
    A191: (L1 
    /\ L4) 
    =  
    {} by 
    TOPREAL1: 20,
    XBOOLE_0:def 7;
    
            (L1
    /\ ( 
    LSeg (p11,p2))) 
    c= (L1 
    /\ L4) by 
    A148,
    Lm27,
    TOPREAL1: 6,
    XBOOLE_1: 26;
    
            then
    
            
    
    A192: (L1 
    /\ ( 
    LSeg (p11,p2))) 
    =  
    {} by 
    A191,
    XBOOLE_1: 3;
    
            (((L3
    \/ L1) 
    \/ L2) 
    /\ ( 
    LSeg (p11,p2))) 
    = (((L3 
    \/ L1) 
    /\ ( 
    LSeg (p11,p2))) 
    \/ (L2 
    /\ ( 
    LSeg (p11,p2)))) by 
    XBOOLE_1: 23
    
            .= (((L3
    /\ ( 
    LSeg (p11,p2))) 
    \/ (L1 
    /\ ( 
    LSeg (p11,p2)))) 
    \/  
    {p11}) by
    A189,
    XBOOLE_1: 23
    
            .=
    {p11} by
    A178,
    A192;
    
            then
    
            
    
    A193: (((L3 
    \/ L1) 
    \/ L2) 
    \/ ( 
    LSeg (p11,p2))) 
    is_an_arc_of (p10,p2) by 
    A171,
    TOPREAL1: 10;
    
            ((
    LSeg (p1,p10)) 
    /\ (((L3 
    \/ L1) 
    \/ L2) 
    \/ ( 
    LSeg (p11,p2)))) 
    = ((( 
    LSeg (p1,p10)) 
    /\ ((L3 
    \/ L1) 
    \/ L2)) 
    \/ (( 
    LSeg (p1,p10)) 
    /\ ( 
    LSeg (p11,p2)))) by 
    XBOOLE_1: 23
    
            .= (((
    LSeg (p1,p10)) 
    /\ (L3 
    \/ L1)) 
    \/ (( 
    LSeg (p1,p10)) 
    /\ L2)) by 
    A165,
    XBOOLE_1: 23
    
            .= (((
    LSeg (p1,p10)) 
    /\ L3) 
    \/ (( 
    LSeg (p1,p10)) 
    /\ L1)) by 
    A174,
    XBOOLE_1: 23
    
            .=
    {p10} by
    A187,
    A164,
    A175,
    TOPREAL1: 16,
    ZFMISC_1: 33;
    
            hence P2
    is_an_arc_of (p1,p2) by 
    A193,
    TOPREAL1: 11;
    
            
    
            thus (P1
    \/ P2) 
    = ((((L3 
    \/ L1) 
    \/ L2) 
    \/ ( 
    LSeg (p11,p2))) 
    \/ (( 
    LSeg (p1,p10)) 
    \/ ( 
    LSeg (p1,p2)))) by 
    XBOOLE_1: 4
    
            .= (((L3
    \/ L1) 
    \/ L2) 
    \/ ((( 
    LSeg (p10,p1)) 
    \/ ( 
    LSeg (p1,p2))) 
    \/ ( 
    LSeg (p2,p11)))) by 
    XBOOLE_1: 4
    
            .= (((L3
    \/ L1) 
    \/ L2) 
    \/ L4) by 
    A3,
    A148,
    TOPREAL1: 7
    
            .= ((L3
    \/ (L1 
    \/ L2)) 
    \/ L4) by 
    XBOOLE_1: 4
    
            .=
    R^2-unit_square by 
    TOPREAL1:def 2,
    XBOOLE_1: 4;
    
            
    
            
    
    A194: p2 
    in ( 
    LSeg (p11,p2)) by 
    RLTOPSP1: 68;
    
            p2
    in ( 
    LSeg (p1,p2)) by 
    RLTOPSP1: 68;
    
            then p2
    in (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p11,p2))) by 
    A194,
    XBOOLE_0:def 4;
    
            then
    {p2}
    c= (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p11,p2))) by 
    ZFMISC_1: 31;
    
            then
    
            
    
    A195: (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p11,p2))) 
    =  
    {p2} by
    A157,
    XBOOLE_0:def 10;
    
            p1
    in ( 
    LSeg (p1,p2)) by 
    RLTOPSP1: 68;
    
            then p1
    in (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p1,p10))) by 
    A190,
    XBOOLE_0:def 4;
    
            then
    {p1}
    c= (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p1,p10))) by 
    ZFMISC_1: 31;
    
            then ((
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p1,p10))) 
    =  
    {p1} by
    A180,
    XBOOLE_0:def 10;
    
            
    
            then
    
            
    
    A196: (P1 
    /\ P2) 
    = ( 
    {p1}
    \/ (( 
    LSeg (p1,p2)) 
    /\ (((L3 
    \/ L1) 
    \/ L2) 
    \/ ( 
    LSeg (p11,p2))))) by 
    XBOOLE_1: 23
    
            .= (
    {p1}
    \/ ((( 
    LSeg (p1,p2)) 
    /\ ((L3 
    \/ L1) 
    \/ L2)) 
    \/  
    {p2})) by
    A195,
    XBOOLE_1: 23
    
            .= (
    {p1}
    \/ (((( 
    LSeg (p1,p2)) 
    /\ (L3 
    \/ L1)) 
    \/ (( 
    LSeg (p1,p2)) 
    /\ L2)) 
    \/  
    {p2})) by
    XBOOLE_1: 23
    
            .= (
    {p1}
    \/ ((((( 
    LSeg (p1,p2)) 
    /\ L3) 
    \/ (( 
    LSeg (p1,p2)) 
    /\ L1)) 
    \/ (( 
    LSeg (p1,p2)) 
    /\ L2)) 
    \/  
    {p2})) by
    XBOOLE_1: 23
    
            .= (
    {p1}
    \/ ((( 
    LSeg (p1,p2)) 
    /\ L3) 
    \/ ((( 
    LSeg (p1,p2)) 
    /\ L2) 
    \/  
    {p2}))) by
    A179,
    XBOOLE_1: 4
    
            .= ((
    {p1}
    \/ (( 
    LSeg (p1,p2)) 
    /\ L3)) 
    \/ ((( 
    LSeg (p1,p2)) 
    /\ L2) 
    \/  
    {p2})) by
    XBOOLE_1: 4;
    
            
    
            
    
    A197: (( 
    LSeg (p1,p2)) 
    /\ L3) 
    c= (L4 
    /\ L3) by 
    A3,
    A148,
    TOPREAL1: 6,
    XBOOLE_1: 26;
    
            
    
    A198: 
    
            now
    
              per cases ;
    
                suppose
    
                
    
    A199: p1 
    = p10; 
    
                then p10
    in ( 
    LSeg (p1,p2)) by 
    RLTOPSP1: 68;
    
                then ((
    LSeg (p1,p2)) 
    /\ L3) 
    <>  
    {} by 
    Lm24,
    XBOOLE_0:def 4;
    
                then ((
    LSeg (p1,p2)) 
    /\ L3) 
    =  
    {p1} by
    A197,
    A199,
    TOPREAL1: 16,
    ZFMISC_1: 33;
    
                hence (P1
    /\ P2) 
    = ( 
    {p1}
    \/ ((( 
    LSeg (p1,p2)) 
    /\ L2) 
    \/  
    {p2})) by
    A196;
    
              end;
    
                suppose
    
                
    
    A200: p1 
    <> p10; 
    
                now
    
                  assume p10
    in (( 
    LSeg (p1,p2)) 
    /\ L3); 
    
                  then p10
    in ( 
    LSeg (p1,p2)) by 
    XBOOLE_0:def 4;
    
                  then (p1
    `2 ) 
    =  
    0 by 
    A13,
    A16,
    A151,
    A156,
    Lm9,
    TOPREAL1: 4;
    
                  hence contradiction by
    A13,
    A14,
    A200,
    EUCLID: 53;
    
                end;
    
                then
    {p10}
    <> (( 
    LSeg (p1,p2)) 
    /\ L3) by 
    ZFMISC_1: 31;
    
                then ((
    LSeg (p1,p2)) 
    /\ L3) 
    =  
    {} by 
    A197,
    TOPREAL1: 16,
    ZFMISC_1: 33;
    
                hence (P1
    /\ P2) 
    = ( 
    {p1}
    \/ ((( 
    LSeg (p1,p2)) 
    /\ L2) 
    \/  
    {p2})) by
    A196;
    
              end;
    
            end;
    
            
    
            
    
    A201: (( 
    LSeg (p1,p2)) 
    /\ L2) 
    c= (L4 
    /\ L2) by 
    A3,
    A148,
    TOPREAL1: 6,
    XBOOLE_1: 26;
    
            now
    
              per cases ;
    
                suppose
    
                
    
    A202: p2 
    = p11; 
    
                then p11
    in ( 
    LSeg (p1,p2)) by 
    RLTOPSP1: 68;
    
                then ((
    LSeg (p1,p2)) 
    /\ L2) 
    <>  
    {} by 
    Lm26,
    XBOOLE_0:def 4;
    
                then ((
    LSeg (p1,p2)) 
    /\ L2) 
    =  
    {p2} by
    A201,
    A202,
    TOPREAL1: 18,
    ZFMISC_1: 33;
    
                hence (P1
    /\ P2) 
    =  
    {p1, p2} by
    A198,
    ENUMSET1: 1;
    
              end;
    
                suppose
    
                
    
    A203: p2 
    <> p11; 
    
                now
    
                  assume p11
    in (( 
    LSeg (p1,p2)) 
    /\ L2); 
    
                  then p11
    in ( 
    LSeg (p1,p2)) by 
    XBOOLE_0:def 4;
    
                  then (p11
    `2 ) 
    <= (p2 
    `2 ) by 
    A13,
    A151,
    A156,
    TOPREAL1: 4;
    
                  then (p2
    `2 ) 
    = 1 by 
    A151,
    A153,
    Lm11,
    XXREAL_0: 1;
    
                  hence contradiction by
    A151,
    A152,
    A203,
    EUCLID: 53;
    
                end;
    
                then
    {p11}
    <> (( 
    LSeg (p1,p2)) 
    /\ L2) by 
    ZFMISC_1: 31;
    
                then ((
    LSeg (p1,p2)) 
    /\ L2) 
    =  
    {} by 
    A201,
    TOPREAL1: 18,
    ZFMISC_1: 33;
    
                hence (P1
    /\ P2) 
    =  
    {p1, p2} by
    A198,
    ENUMSET1: 1;
    
              end;
    
            end;
    
            hence (P1
    /\ P2) 
    =  
    {p1, p2};
    
          end;
    
            suppose
    
            
    
    A204: (q 
    `2 ) 
    < (p 
    `2 ); 
    
            
    
            
    
    A205: (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p10,p2))) 
    c=  
    {p2}
    
            proof
    
              let a be
    object;
    
              assume
    
              
    
    A206: a 
    in (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p10,p2))); 
    
              then
    
              reconsider p = a as
    Point of ( 
    TOP-REAL 2); 
    
              
    
              
    
    A207: p 
    in ( 
    LSeg (p10,p2)) by 
    A206,
    XBOOLE_0:def 4;
    
              (p10
    `2 ) 
    <= (p2 
    `2 ) by 
    A151,
    A154,
    EUCLID: 52;
    
              then
    
              
    
    A208: (p 
    `2 ) 
    <= (p2 
    `2 ) by 
    A207,
    TOPREAL1: 4;
    
              
    
              
    
    A209: p 
    in ( 
    LSeg (p2,p1)) by 
    A206,
    XBOOLE_0:def 4;
    
              then
    
              
    
    A210: (p2 
    `1 ) 
    <= (p 
    `1 ) by 
    A13,
    A14,
    A151,
    A152,
    TOPREAL1: 3;
    
              (p2
    `2 ) 
    <= (p 
    `2 ) by 
    A13,
    A151,
    A204,
    A209,
    TOPREAL1: 4;
    
              then
    
              
    
    A211: (p2 
    `2 ) 
    = (p 
    `2 ) by 
    A208,
    XXREAL_0: 1;
    
              (p
    `1 ) 
    <= (p1 
    `1 ) by 
    A13,
    A14,
    A151,
    A152,
    A209,
    TOPREAL1: 3;
    
              then (p
    `1 ) 
    = 1 by 
    A13,
    A14,
    A151,
    A152,
    A210,
    XXREAL_0: 1;
    
              
    
              then p
    =  
    |[1, (p2
    `2 )]| by 
    A211,
    EUCLID: 53
    
              .= p2 by
    A151,
    A152,
    EUCLID: 53;
    
              hence thesis by
    TARSKI:def 1;
    
            end;
    
            p11
    in ( 
    LSeg (p1,p11)) by 
    RLTOPSP1: 68;
    
            then
    
            
    
    A212: (( 
    LSeg (p1,p11)) 
    /\ L2) 
    <>  
    {} by 
    Lm26,
    XBOOLE_0:def 4;
    
            
    
    A213: 
    
            now
    
              set a = the
    Element of (( 
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p10,p2))); 
    
              assume
    
              
    
    A214: (( 
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p10,p2))) 
    <>  
    {} ; 
    
              then
    
              reconsider p = a as
    Point of ( 
    TOP-REAL 2) by 
    TARSKI:def 3;
    
              
    
              
    
    A215: p 
    in ( 
    LSeg (p1,p11)) by 
    A214,
    XBOOLE_0:def 4;
    
              
    
              
    
    A216: p 
    in ( 
    LSeg (p10,p2)) by 
    A214,
    XBOOLE_0:def 4;
    
              (p10
    `2 ) 
    <= (p2 
    `2 ) by 
    A151,
    A154,
    EUCLID: 52;
    
              then
    
              
    
    A217: (p 
    `2 ) 
    <= (p2 
    `2 ) by 
    A216,
    TOPREAL1: 4;
    
              (p1
    `2 ) 
    <= (p11 
    `2 ) by 
    A13,
    A15,
    EUCLID: 52;
    
              then (p1
    `2 ) 
    <= (p 
    `2 ) by 
    A215,
    TOPREAL1: 4;
    
              hence contradiction by
    A13,
    A151,
    A204,
    A217,
    XXREAL_0: 2;
    
            end;
    
            
    
            
    
    A218: ((L2 
    \/ L1) 
    /\ L3) 
    = ((L3 
    /\ L2) 
    \/ (L1 
    /\ L3)) by 
    XBOOLE_1: 23
    
            .=
    {p00} by
    Lm2,
    TOPREAL1: 17;
    
            (L2
    \/ L1) 
    is_an_arc_of (p11,p00) by 
    Lm6,
    Lm10,
    TOPREAL1: 9,
    TOPREAL1: 10,
    TOPREAL1: 15;
    
            then
    
            
    
    A219: ((L2 
    \/ L1) 
    \/ L3) 
    is_an_arc_of (p11,p10) by 
    A218,
    TOPREAL1: 10;
    
            now
    
              assume p11
    in (L2 
    /\ ( 
    LSeg (p10,p2))); 
    
              then
    
              
    
    A220: p11 
    in ( 
    LSeg (p10,p2)) by 
    XBOOLE_0:def 4;
    
              (p10
    `2 ) 
    <= (p2 
    `2 ) by 
    A151,
    A154,
    EUCLID: 52;
    
              then (p11
    `2 ) 
    <= (p2 
    `2 ) by 
    A220,
    TOPREAL1: 4;
    
              hence contradiction by
    A15,
    A151,
    A153,
    A204,
    Lm11,
    XXREAL_0: 1;
    
            end;
    
            then
    
            
    
    A221: 
    {p11}
    <> (L2 
    /\ ( 
    LSeg (p10,p2))) by 
    ZFMISC_1: 31;
    
            (L2
    /\ ( 
    LSeg (p10,p2))) 
    c=  
    {p11} by
    A148,
    Lm25,
    TOPREAL1: 6,
    TOPREAL1: 18,
    XBOOLE_1: 26;
    
            then
    
            
    
    A222: (L2 
    /\ ( 
    LSeg (p10,p2))) 
    =  
    {} by 
    A221,
    ZFMISC_1: 33;
    
            (L1
    /\ L4) 
    =  
    {} by 
    TOPREAL1: 20,
    XBOOLE_0:def 7;
    
            then
    
            
    
    A223: (( 
    LSeg (p1,p11)) 
    /\ L1) 
    =  
    {} by 
    A5,
    XBOOLE_1: 3,
    XBOOLE_1: 26;
    
            now
    
              assume p10
    in (( 
    LSeg (p1,p11)) 
    /\ L3); 
    
              then
    
              
    
    A224: p10 
    in ( 
    LSeg (p1,p11)) by 
    XBOOLE_0:def 4;
    
              (p1
    `2 ) 
    <= (p11 
    `2 ) by 
    A13,
    A15,
    EUCLID: 52;
    
              hence contradiction by
    A13,
    A154,
    A204,
    A224,
    Lm9,
    TOPREAL1: 4;
    
            end;
    
            then
    
            
    
    A225: 
    {p10}
    <> (( 
    LSeg (p1,p11)) 
    /\ L3) by 
    ZFMISC_1: 31;
    
            ((
    LSeg (p1,p11)) 
    /\ L3) 
    c= (L4 
    /\ L3) by 
    A3,
    Lm27,
    TOPREAL1: 6,
    XBOOLE_1: 26;
    
            then
    
            
    
    A226: (( 
    LSeg (p1,p11)) 
    /\ L3) 
    =  
    {} by 
    A225,
    TOPREAL1: 16,
    ZFMISC_1: 33;
    
            (L1
    /\ L4) 
    =  
    {} by 
    TOPREAL1: 20,
    XBOOLE_0:def 7;
    
            then
    
            
    
    A227: (( 
    LSeg (p1,p2)) 
    /\ L1) 
    =  
    {} by 
    A150,
    XBOOLE_1: 3,
    XBOOLE_1: 26;
    
            
    
            
    
    A228: (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p1,p11))) 
    c=  
    {p1}
    
            proof
    
              let a be
    object;
    
              assume
    
              
    
    A229: a 
    in (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p1,p11))); 
    
              then
    
              reconsider p = a as
    Point of ( 
    TOP-REAL 2); 
    
              
    
              
    
    A230: p 
    in ( 
    LSeg (p1,p11)) by 
    A229,
    XBOOLE_0:def 4;
    
              (p1
    `2 ) 
    <= (p11 
    `2 ) by 
    A13,
    A15,
    EUCLID: 52;
    
              then
    
              
    
    A231: (p1 
    `2 ) 
    <= (p 
    `2 ) by 
    A230,
    TOPREAL1: 4;
    
              
    
              
    
    A232: p 
    in ( 
    LSeg (p2,p1)) by 
    A229,
    XBOOLE_0:def 4;
    
              then
    
              
    
    A233: (p2 
    `1 ) 
    <= (p 
    `1 ) by 
    A13,
    A14,
    A151,
    A152,
    TOPREAL1: 3;
    
              (p
    `2 ) 
    <= (p1 
    `2 ) by 
    A13,
    A151,
    A204,
    A232,
    TOPREAL1: 4;
    
              then
    
              
    
    A234: (p1 
    `2 ) 
    = (p 
    `2 ) by 
    A231,
    XXREAL_0: 1;
    
              (p
    `1 ) 
    <= (p1 
    `1 ) by 
    A13,
    A14,
    A151,
    A152,
    A232,
    TOPREAL1: 3;
    
              then (p
    `1 ) 
    = 1 by 
    A13,
    A14,
    A151,
    A152,
    A233,
    XXREAL_0: 1;
    
              
    
              then p
    =  
    |[1, (p1
    `2 )]| by 
    A234,
    EUCLID: 53
    
              .= p1 by
    A13,
    A14,
    EUCLID: 53;
    
              hence thesis by
    TARSKI:def 1;
    
            end;
    
            
    
            
    
    A235: (( 
    LSeg (p1,p11)) 
    /\ L2) 
    c= (L4 
    /\ L2) by 
    A3,
    Lm27,
    TOPREAL1: 6,
    XBOOLE_1: 26;
    
            p10
    in ( 
    LSeg (p10,p2)) by 
    RLTOPSP1: 68;
    
            then
    
            
    
    A236: (L3 
    /\ ( 
    LSeg (p10,p2))) 
    <>  
    {} by 
    Lm24,
    XBOOLE_0:def 4;
    
            (L3
    /\ ( 
    LSeg (p10,p2))) 
    c=  
    {p10} by
    A148,
    Lm25,
    TOPREAL1: 6,
    TOPREAL1: 16,
    XBOOLE_1: 26;
    
            then
    
            
    
    A237: (L3 
    /\ ( 
    LSeg (p10,p2))) 
    =  
    {p10} by
    A236,
    ZFMISC_1: 33;
    
            take P1 = (
    LSeg (p1,p2)), P2 = (( 
    LSeg (p1,p11)) 
    \/ (((L2 
    \/ L1) 
    \/ L3) 
    \/ ( 
    LSeg (p10,p2)))); 
    
            
    
            
    
    A238: p1 
    in ( 
    LSeg (p1,p11)) by 
    RLTOPSP1: 68;
    
            thus P1
    is_an_arc_of (p1,p2) by 
    A1,
    TOPREAL1: 9;
    
            
    
            
    
    A239: (L1 
    /\ L4) 
    =  
    {} by 
    TOPREAL1: 20,
    XBOOLE_0:def 7;
    
            (L1
    /\ ( 
    LSeg (p10,p2))) 
    c= (L1 
    /\ L4) by 
    A148,
    Lm25,
    TOPREAL1: 6,
    XBOOLE_1: 26;
    
            then
    
            
    
    A240: (L1 
    /\ ( 
    LSeg (p10,p2))) 
    =  
    {} by 
    A239,
    XBOOLE_1: 3;
    
            (((L2
    \/ L1) 
    \/ L3) 
    /\ ( 
    LSeg (p10,p2))) 
    = (((L2 
    \/ L1) 
    /\ ( 
    LSeg (p10,p2))) 
    \/ (L3 
    /\ ( 
    LSeg (p10,p2)))) by 
    XBOOLE_1: 23
    
            .= (((L2
    /\ ( 
    LSeg (p10,p2))) 
    \/ (L1 
    /\ ( 
    LSeg (p10,p2)))) 
    \/  
    {p10}) by
    A237,
    XBOOLE_1: 23
    
            .=
    {p10} by
    A222,
    A240;
    
            then
    
            
    
    A241: (((L2 
    \/ L1) 
    \/ L3) 
    \/ ( 
    LSeg (p10,p2))) 
    is_an_arc_of (p11,p2) by 
    A219,
    TOPREAL1: 10;
    
            ((
    LSeg (p1,p11)) 
    /\ (((L2 
    \/ L1) 
    \/ L3) 
    \/ ( 
    LSeg (p10,p2)))) 
    = ((( 
    LSeg (p1,p11)) 
    /\ ((L2 
    \/ L1) 
    \/ L3)) 
    \/ (( 
    LSeg (p1,p11)) 
    /\ ( 
    LSeg (p10,p2)))) by 
    XBOOLE_1: 23
    
            .= (((
    LSeg (p1,p11)) 
    /\ (L2 
    \/ L1)) 
    \/ (( 
    LSeg (p1,p11)) 
    /\ L3)) by 
    A213,
    XBOOLE_1: 23
    
            .= (((
    LSeg (p1,p11)) 
    /\ L2) 
    \/ (( 
    LSeg (p1,p11)) 
    /\ L1)) by 
    A226,
    XBOOLE_1: 23
    
            .=
    {p11} by
    A235,
    A212,
    A223,
    TOPREAL1: 18,
    ZFMISC_1: 33;
    
            hence P2
    is_an_arc_of (p1,p2) by 
    A241,
    TOPREAL1: 11;
    
            
    
            thus (P1
    \/ P2) 
    = ((((L2 
    \/ L1) 
    \/ L3) 
    \/ ( 
    LSeg (p10,p2))) 
    \/ (( 
    LSeg (p1,p11)) 
    \/ ( 
    LSeg (p1,p2)))) by 
    XBOOLE_1: 4
    
            .= (((L2
    \/ L1) 
    \/ L3) 
    \/ (( 
    LSeg (p10,p2)) 
    \/ (( 
    LSeg (p1,p2)) 
    \/ ( 
    LSeg (p1,p11))))) by 
    XBOOLE_1: 4
    
            .= (((L1
    \/ L2) 
    \/ L3) 
    \/ L4) by 
    A3,
    A148,
    TOPREAL1: 7
    
            .=
    R^2-unit_square by 
    TOPREAL1:def 2,
    XBOOLE_1: 4;
    
            
    
            
    
    A242: p2 
    in ( 
    LSeg (p10,p2)) by 
    RLTOPSP1: 68;
    
            p2
    in ( 
    LSeg (p1,p2)) by 
    RLTOPSP1: 68;
    
            then p2
    in (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p10,p2))) by 
    A242,
    XBOOLE_0:def 4;
    
            then
    {p2}
    c= (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p10,p2))) by 
    ZFMISC_1: 31;
    
            then
    
            
    
    A243: (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p10,p2))) 
    =  
    {p2} by
    A205,
    XBOOLE_0:def 10;
    
            p1
    in ( 
    LSeg (p1,p2)) by 
    RLTOPSP1: 68;
    
            then p1
    in (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p1,p11))) by 
    A238,
    XBOOLE_0:def 4;
    
            then
    {p1}
    c= (( 
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p1,p11))) by 
    ZFMISC_1: 31;
    
            then ((
    LSeg (p1,p2)) 
    /\ ( 
    LSeg (p1,p11))) 
    =  
    {p1} by
    A228,
    XBOOLE_0:def 10;
    
            
    
            then
    
            
    
    A244: (P1 
    /\ P2) 
    = ( 
    {p1}
    \/ (( 
    LSeg (p1,p2)) 
    /\ (((L2 
    \/ L1) 
    \/ L3) 
    \/ ( 
    LSeg (p10,p2))))) by 
    XBOOLE_1: 23
    
            .= (
    {p1}
    \/ ((( 
    LSeg (p1,p2)) 
    /\ ((L2 
    \/ L1) 
    \/ L3)) 
    \/  
    {p2})) by
    A243,
    XBOOLE_1: 23
    
            .= (
    {p1}
    \/ (((( 
    LSeg (p1,p2)) 
    /\ (L2 
    \/ L1)) 
    \/ (( 
    LSeg (p1,p2)) 
    /\ L3)) 
    \/  
    {p2})) by
    XBOOLE_1: 23
    
            .= (
    {p1}
    \/ ((((( 
    LSeg (p1,p2)) 
    /\ L2) 
    \/ (( 
    LSeg (p1,p2)) 
    /\ L1)) 
    \/ (( 
    LSeg (p1,p2)) 
    /\ L3)) 
    \/  
    {p2})) by
    XBOOLE_1: 23
    
            .= (
    {p1}
    \/ ((( 
    LSeg (p1,p2)) 
    /\ L2) 
    \/ ((( 
    LSeg (p1,p2)) 
    /\ L3) 
    \/  
    {p2}))) by
    A227,
    XBOOLE_1: 4
    
            .= ((
    {p1}
    \/ (( 
    LSeg (p1,p2)) 
    /\ L2)) 
    \/ ((( 
    LSeg (p1,p2)) 
    /\ L3) 
    \/  
    {p2})) by
    XBOOLE_1: 4;
    
            
    
            
    
    A245: (( 
    LSeg (p1,p2)) 
    /\ L2) 
    c= (L4 
    /\ L2) by 
    A3,
    A148,
    TOPREAL1: 6,
    XBOOLE_1: 26;
    
            
    
    A246: 
    
            now
    
              per cases ;
    
                suppose
    
                
    
    A247: p1 
    = p11; 
    
                then p11
    in ( 
    LSeg (p1,p2)) by 
    RLTOPSP1: 68;
    
                then ((
    LSeg (p1,p2)) 
    /\ L2) 
    <>  
    {} by 
    Lm26,
    XBOOLE_0:def 4;
    
                then ((
    LSeg (p1,p2)) 
    /\ L2) 
    =  
    {p1} by
    A245,
    A247,
    TOPREAL1: 18,
    ZFMISC_1: 33;
    
                hence (P1
    /\ P2) 
    = ( 
    {p1}
    \/ ((( 
    LSeg (p1,p2)) 
    /\ L3) 
    \/  
    {p2})) by
    A244;
    
              end;
    
                suppose
    
                
    
    A248: p1 
    <> p11; 
    
                now
    
                  assume p11
    in (( 
    LSeg (p1,p2)) 
    /\ L2); 
    
                  then p11
    in ( 
    LSeg (p2,p1)) by 
    XBOOLE_0:def 4;
    
                  then (p11
    `2 ) 
    <= (p1 
    `2 ) by 
    A13,
    A151,
    A204,
    TOPREAL1: 4;
    
                  then (p1
    `2 ) 
    = 1 by 
    A13,
    A15,
    Lm11,
    XXREAL_0: 1;
    
                  hence contradiction by
    A13,
    A14,
    A248,
    EUCLID: 53;
    
                end;
    
                then
    {p11}
    <> (( 
    LSeg (p1,p2)) 
    /\ L2) by 
    ZFMISC_1: 31;
    
                then ((
    LSeg (p1,p2)) 
    /\ L2) 
    =  
    {} by 
    A245,
    TOPREAL1: 18,
    ZFMISC_1: 33;
    
                hence (P1
    /\ P2) 
    = ( 
    {p1}
    \/ ((( 
    LSeg (p1,p2)) 
    /\ L3) 
    \/  
    {p2})) by
    A244;
    
              end;
    
            end;
    
            
    
            
    
    A249: (( 
    LSeg (p1,p2)) 
    /\ L3) 
    c= (L4 
    /\ L3) by 
    A3,
    A148,
    TOPREAL1: 6,
    XBOOLE_1: 26;
    
            now
    
              per cases ;
    
                suppose
    
                
    
    A250: p2 
    = p10; 
    
                then p10
    in ( 
    LSeg (p1,p2)) by 
    RLTOPSP1: 68;
    
                then ((
    LSeg (p1,p2)) 
    /\ L3) 
    <>  
    {} by 
    Lm24,
    XBOOLE_0:def 4;
    
                then ((
    LSeg (p1,p2)) 
    /\ L3) 
    =  
    {p2} by
    A249,
    A250,
    TOPREAL1: 16,
    ZFMISC_1: 33;
    
                hence (P1
    /\ P2) 
    =  
    {p1, p2} by
    A246,
    ENUMSET1: 1;
    
              end;
    
                suppose
    
                
    
    A251: p2 
    <> p10; 
    
                now
    
                  assume p10
    in (( 
    LSeg (p1,p2)) 
    /\ L3); 
    
                  then p10
    in ( 
    LSeg (p2,p1)) by 
    XBOOLE_0:def 4;
    
                  then (p2
    `2 ) 
    =  
    0 by 
    A13,
    A151,
    A154,
    A204,
    Lm9,
    TOPREAL1: 4;
    
                  hence contradiction by
    A151,
    A152,
    A251,
    EUCLID: 53;
    
                end;
    
                then
    {p10}
    <> (( 
    LSeg (p1,p2)) 
    /\ L3) by 
    ZFMISC_1: 31;
    
                then ((
    LSeg (p1,p2)) 
    /\ L3) 
    =  
    {} by 
    A249,
    TOPREAL1: 16,
    ZFMISC_1: 33;
    
                hence (P1
    /\ P2) 
    =  
    {p1, p2} by
    A246,
    ENUMSET1: 1;
    
              end;
    
            end;
    
            hence (P1
    /\ P2) 
    =  
    {p1, p2};
    
          end;
    
        end;
    
        hence thesis;
    
      end;
    
    end;
    
    theorem :: 
    
    TOPREAL2:1
    
    
    
    
    
    Th1: p1 
    <> p2 & p1 
    in  
    R^2-unit_square & p2 
    in  
    R^2-unit_square implies ex P1,P2 be non 
    empty  
    Subset of ( 
    TOP-REAL 2) st P1 
    is_an_arc_of (p1,p2) & P2 
    is_an_arc_of (p1,p2) & 
    R^2-unit_square  
    = (P1 
    \/ P2) & (P1 
    /\ P2) 
    =  
    {p1, p2}
    
    proof
    
      assume that
    
      
    
    A1: p1 
    <> p2 and 
    
      
    
    A2: p1 
    in  
    R^2-unit_square and 
    
      
    
    A3: p2 
    in  
    R^2-unit_square ; 
    
      
    
      
    
    A4: p1 
    in (L1 
    \/ L2) or p1 
    in (L3 
    \/ L4) by 
    A2,
    TOPREAL1:def 2,
    XBOOLE_0:def 3;
    
      per cases by
    A4,
    XBOOLE_0:def 3;
    
        suppose p1
    in L1; 
    
        hence thesis by
    A1,
    A3,
    Lm30;
    
      end;
    
        suppose p1
    in L2; 
    
        hence thesis by
    A1,
    A3,
    Lm31;
    
      end;
    
        suppose p1
    in L3; 
    
        hence thesis by
    A1,
    A3,
    Lm32;
    
      end;
    
        suppose p1
    in L4; 
    
        hence thesis by
    A1,
    A3,
    Lm33;
    
      end;
    
    end;
    
    theorem :: 
    
    TOPREAL2:2
    
    
    
    
    
    Th2: 
    R^2-unit_square is 
    compact
    
    proof
    
      
    
      
    
    A1: 
    I[01] is 
    compact by 
    HEINE: 4,
    TOPMETR: 20;
    
      consider P1,P2 be non
    empty  
    Subset of ( 
    TOP-REAL 2) such that 
    
      
    
    A2: P1 is 
    being_S-P_arc and 
    
      
    
    A3: P2 is 
    being_S-P_arc and 
    
      
    
    A4: 
    R^2-unit_square  
    = (P1 
    \/ P2) by 
    TOPREAL1: 27;
    
      consider f be
    Function of 
    I[01] , (( 
    TOP-REAL 2) 
    | P1) such that 
    
      
    
    A5: f is 
    being_homeomorphism by 
    A2,
    TOPREAL1: 29;
    
      
    
      
    
    A6: ( 
    rng f) 
    = ( 
    [#] (( 
    TOP-REAL 2) 
    | P1)) by 
    A5;
    
      consider f0 be
    Function of 
    I[01] , (( 
    TOP-REAL 2) 
    | P2) such that 
    
      
    
    A7: f0 is 
    being_homeomorphism by 
    A3,
    TOPREAL1: 29;
    
      
    
      
    
    A8: ( 
    rng f0) 
    = ( 
    [#] (( 
    TOP-REAL 2) 
    | P2)) by 
    A7;
    
      reconsider P2 as non
    empty  
    Subset of ( 
    TOP-REAL 2); 
    
      f0 is
    continuous by 
    A7;
    
      then ((
    TOP-REAL 2) 
    | P2) is 
    compact by 
    A1,
    A8,
    COMPTS_1: 14;
    
      then
    
      
    
    A9: P2 is 
    compact by 
    COMPTS_1: 3;
    
      reconsider P1 as non
    empty  
    Subset of ( 
    TOP-REAL 2); 
    
      f is
    continuous by 
    A5;
    
      then ((
    TOP-REAL 2) 
    | P1) is 
    compact by 
    A1,
    A6,
    COMPTS_1: 14;
    
      then P1 is
    compact by 
    COMPTS_1: 3;
    
      hence thesis by
    A4,
    A9,
    COMPTS_1: 10;
    
    end;
    
    theorem :: 
    
    TOPREAL2:3
    
    
    
    
    
    Th3: for Q,P be non 
    empty  
    Subset of ( 
    TOP-REAL 2) holds for f be 
    Function of (( 
    TOP-REAL 2) 
    | Q), (( 
    TOP-REAL 2) 
    | P) st f is 
    being_homeomorphism & Q 
    is_an_arc_of (q1,q2) holds for p1, p2 st p1 
    = (f 
    . q1) & p2 
    = (f 
    . q2) holds P 
    is_an_arc_of (p1,p2) 
    
    proof
    
      let Q,P be non
    empty  
    Subset of ( 
    TOP-REAL 2); 
    
      let f be
    Function of (( 
    TOP-REAL 2) 
    | Q), (( 
    TOP-REAL 2) 
    | P); 
    
      assume that
    
      
    
    A1: f is 
    being_homeomorphism and 
    
      
    
    A2: Q 
    is_an_arc_of (q1,q2); 
    
      let p1, p2 such that
    
      
    
    A3: p1 
    = (f 
    . q1) and 
    
      
    
    A4: p2 
    = (f 
    . q2); 
    
      reconsider f as
    Function of (( 
    TOP-REAL 2) 
    | Q), (( 
    TOP-REAL 2) 
    | P); 
    
      consider f1 be
    Function of 
    I[01] , (( 
    TOP-REAL 2) 
    | Q) such that 
    
      
    
    A5: f1 is 
    being_homeomorphism and 
    
      
    
    A6: (f1 
    .  
    0 ) 
    = q1 and 
    
      
    
    A7: (f1 
    . 1) 
    = q2 by 
    A2,
    TOPREAL1:def 1;
    
      set g1 = (f
    * f1); 
    
      
    
      
    
    A8: ( 
    dom f1) 
    = the 
    carrier of 
    I[01] by 
    FUNCT_2:def 1;
    
      then
    0  
    in ( 
    dom f1) by 
    BORSUK_1: 40,
    XXREAL_1: 1;
    
      then
    
      
    
    A9: (g1 
    .  
    0 ) 
    = p1 by 
    A3,
    A6,
    FUNCT_1: 13;
    
      1
    in ( 
    dom f1) by 
    A8,
    BORSUK_1: 40,
    XXREAL_1: 1;
    
      then
    
      
    
    A10: (g1 
    . 1) 
    = p2 by 
    A4,
    A7,
    FUNCT_1: 13;
    
      g1 is
    being_homeomorphism by 
    A1,
    A5,
    TOPS_2: 57;
    
      hence thesis by
    A9,
    A10,
    TOPREAL1:def 1;
    
    end;
    
    definition
    
      let P be
    Subset of ( 
    TOP-REAL 2); 
    
      :: 
    
    TOPREAL2:def1
    
      attr P is
    
    being_simple_closed_curve means ex f be 
    Function of (( 
    TOP-REAL 2) 
    |  
    R^2-unit_square ), (( 
    TOP-REAL 2) 
    | P) st f is 
    being_homeomorphism;
    
    end
    
    registration
    
      cluster 
    R^2-unit_square -> 
    being_simple_closed_curve;
    
      coherence
    
      proof
    
        set T = ((
    TOP-REAL 2) 
    |  
    R^2-unit_square ); 
    
        take f = (
    id T); 
    
        thus (
    dom f) 
    = ( 
    [#] T) by 
    FUNCT_2:def 1;
    
        thus (
    rng f) 
    = ( 
    [#] T) by 
    RELAT_1: 45;
    
        then f is
    onto
    one-to-one by 
    FUNCT_2:def 3;
    
        
    
        then
    
        
    
    A1: (f 
    " ) 
    = (f qua 
    Function
    " ) by 
    TOPS_2:def 4
    
        .= f by
    FUNCT_1: 45;
    
        thus f is
    one-to-one;
    
        thus f is
    continuous by 
    FUNCT_2: 94;
    
        hence thesis by
    A1;
    
      end;
    
    end
    
    registration
    
      cluster 
    being_simple_closed_curve non 
    empty for 
    Subset of ( 
    TOP-REAL 2); 
    
      existence
    
      proof
    
        take
    R^2-unit_square ; 
    
        thus thesis;
    
      end;
    
    end
    
    definition
    
      mode
    
    Simple_closed_curve is 
    being_simple_closed_curve  
    Subset of ( 
    TOP-REAL 2); 
    
    end
    
    theorem :: 
    
    TOPREAL2:4
    
    
    
    
    
    Th4: for P be non 
    empty  
    Subset of ( 
    TOP-REAL 2) st P is 
    being_simple_closed_curve holds ex p1, p2 st p1 
    <> p2 & p1 
    in P & p2 
    in P 
    
    proof
    
      reconsider RS =
    R^2-unit_square as non 
    empty  
    Subset of ( 
    TOP-REAL 2); 
    
      let P be non
    empty  
    Subset of ( 
    TOP-REAL 2); 
    
      
    
      
    
    A1: (p00 
    `1 ) 
    =  
    0 by 
    EUCLID: 52;
    
      
    
      
    
    A2: ( 
    [#] (( 
    TOP-REAL 2) 
    | P)) 
    c= ( 
    [#] ( 
    TOP-REAL 2)) by 
    PRE_TOPC:def 4;
    
      
    
      
    
    A3: (p11 
    `1 ) 
    = 1 by 
    EUCLID: 52;
    
      assume P is
    being_simple_closed_curve;
    
      then
    
      consider f be
    Function of (( 
    TOP-REAL 2) 
    |  
    R^2-unit_square ), (( 
    TOP-REAL 2) 
    | P) such that 
    
      
    
    A4: f is 
    being_homeomorphism;
    
      
    
      
    
    A5: ( 
    rng f) 
    = ( 
    [#] (( 
    TOP-REAL 2) 
    | P)) by 
    A4
    
      .= P by
    PRE_TOPC:def 5;
    
      reconsider f as
    Function of (( 
    TOP-REAL 2) 
    | RS), (( 
    TOP-REAL 2) 
    | P); 
    
      
    
      
    
    A6: ( 
    dom f) 
    = ( 
    [#] (( 
    TOP-REAL 2) 
    | RS)) by 
    FUNCT_2:def 1
    
      .=
    R^2-unit_square by 
    PRE_TOPC:def 5;
    
      set p1 = (f
    . p00), p2 = (f 
    . p11); 
    
      (p00
    `2 ) 
    =  
    0 by 
    EUCLID: 52;
    
      then
    
      
    
    A7: p00 
    in ( 
    dom f) by 
    A1,
    A6,
    TOPREAL1: 14;
    
      then
    
      
    
    A8: p1 
    in ( 
    rng f) by 
    FUNCT_1:def 3;
    
      (p11
    `2 ) 
    = 1 by 
    EUCLID: 52;
    
      then
    
      
    
    A9: p11 
    in ( 
    dom f) by 
    A3,
    A6,
    TOPREAL1: 14;
    
      then
    
      
    
    A10: p2 
    in ( 
    rng f) by 
    FUNCT_1:def 3;
    
      reconsider p1, p2 as
    Point of ( 
    TOP-REAL 2) by 
    A2,
    A8,
    A10;
    
      take p1, p2;
    
      f is
    one-to-one by 
    A4;
    
      hence p1
    <> p2 by 
    A1,
    A3,
    A7,
    A9,
    FUNCT_1:def 4;
    
      thus thesis by
    A5,
    A7,
    A9,
    FUNCT_1:def 3;
    
    end;
    
    
    
    
    
    Lm34: for P,P1,P2 be non 
    empty  
    Subset of ( 
    TOP-REAL 2) st P1 
    is_an_arc_of (p1,p2) & P2 
    is_an_arc_of (p1,p2) & P 
    = (P1 
    \/ P2) & (P1 
    /\ P2) 
    =  
    {p1, p2} holds P is
    being_simple_closed_curve
    
    proof
    
      reconsider RS =
    R^2-unit_square as non 
    empty  
    Subset of ( 
    TOP-REAL 2); 
    
      let P,P1,P2 be non
    empty  
    Subset of ( 
    TOP-REAL 2) such that 
    
      
    
    A1: P1 
    is_an_arc_of (p1,p2) and 
    
      
    
    A2: P2 
    is_an_arc_of (p1,p2) and 
    
      
    
    A3: P 
    = (P1 
    \/ P2) and 
    
      
    
    A4: (P1 
    /\ P2) 
    =  
    {p1, p2};
    
      reconsider P9 = P, P19 = P1, P29 = P2 as non
    empty  
    Subset of ( 
    TOP-REAL 2); 
    
      
    
      
    
    A5: ( 
    [#] (( 
    TOP-REAL 2) 
    | P1)) 
    = P1 by 
    PRE_TOPC:def 5;
    
      consider h1, h2 such that
    
      
    
    A6: h1 is 
    being_S-Seq and 
    
      
    
    A7: h2 is 
    being_S-Seq and 
    
      
    
    A8: 
    R^2-unit_square  
    = (( 
    L~ h1) 
    \/ ( 
    L~ h2)) and 
    
      
    
    A9: (( 
    L~ h1) 
    /\ ( 
    L~ h2)) 
    =  
    {p00, p11} and
    
      
    
    A10: (h1 
    /. 1) 
    = p00 and 
    
      
    
    A11: (h1 
    /. ( 
    len h1)) 
    = p11 and 
    
      
    
    A12: (h2 
    /. 1) 
    = p00 and 
    
      
    
    A13: (h2 
    /. ( 
    len h2)) 
    = p11 by 
    TOPREAL1: 24;
    
      
    
      
    
    A14: ( 
    len h2) 
    >= 2 by 
    A7,
    TOPREAL1:def 8;
    
      (
    len h1) 
    >= 2 by 
    A6,
    TOPREAL1:def 8;
    
      then
    
      reconsider Lh1 = (
    L~ h1), Lh2 = ( 
    L~ h2) as non 
    empty  
    Subset of ( 
    TOP-REAL 2) by 
    A14,
    TOPREAL1: 23;
    
      set T1 = ((
    TOP-REAL 2) 
    | Lh1), T2 = (( 
    TOP-REAL 2) 
    | Lh2), T = (( 
    TOP-REAL 2) 
    | RS); 
    
      
    
      
    
    A15: ( 
    [#] T) 
    =  
    R^2-unit_square by 
    PRE_TOPC:def 5;
    
      
    
      
    
    A16: ( 
    [#] T2) 
    = ( 
    L~ h2) by 
    PRE_TOPC:def 5;
    
      then
    
      
    
    A17: T2 is 
    SubSpace of T by 
    A8,
    A15,
    TOPMETR: 3,
    XBOOLE_1: 7;
    
      
    
      
    
    A18: ( 
    [#] T1) 
    = ( 
    L~ h1) by 
    PRE_TOPC:def 5;
    
      then
    
      
    
    A19: T1 is 
    SubSpace of T by 
    A8,
    A15,
    TOPMETR: 3,
    XBOOLE_1: 7;
    
      
    
      
    
    A20: ( 
    [#] (( 
    TOP-REAL 2) 
    | P)) 
    = P by 
    PRE_TOPC:def 5;
    
      
    
      
    
    A21: ( 
    [#] (( 
    TOP-REAL 2) 
    | P2)) 
    = P2 by 
    PRE_TOPC:def 5;
    
      then
    
      
    
    A22: (( 
    TOP-REAL 2) 
    | P29) is 
    SubSpace of (( 
    TOP-REAL 2) 
    | P9) by 
    A3,
    A20,
    TOPMETR: 3,
    XBOOLE_1: 7;
    
      consider f2 be
    Function of 
    I[01] , (( 
    TOP-REAL 2) 
    | P2) such that 
    
      
    
    A23: f2 is 
    being_homeomorphism and 
    
      
    
    A24: (f2 
    .  
    0 ) 
    = p1 and 
    
      
    
    A25: (f2 
    . 1) 
    = p2 by 
    A2,
    TOPREAL1:def 1;
    
      
    
      
    
    A26: ( 
    dom f2) 
    = the 
    carrier of 
    I[01] by 
    FUNCT_2:def 1;
    
      P2
    c= P by 
    A3,
    XBOOLE_1: 7;
    
      then (
    rng f2) 
    c= the 
    carrier of (( 
    TOP-REAL 2) 
    | P) by 
    A21,
    A20;
    
      then
    
      reconsider ff2 = f2 as
    Function of 
    I[01] , (( 
    TOP-REAL 2) 
    | P9) by 
    A26,
    RELSET_1: 4;
    
      
    
      
    
    A27: ( 
    dom ff2) 
    = the 
    carrier of 
    I[01] by 
    FUNCT_2:def 1;
    
      then
    
      
    
    A28: 
    0  
    in ( 
    dom ff2) by 
    BORSUK_1: 40,
    XXREAL_1: 1;
    
      f2 is
    continuous by 
    A23;
    
      then
    
      
    
    A29: ff2 is 
    continuous by 
    A22,
    PRE_TOPC: 26;
    
      
    
      
    
    A30: 1 
    in ( 
    dom ff2) by 
    A27,
    BORSUK_1: 40,
    XXREAL_1: 1;
    
      
    
      
    
    A31: ( 
    [#] (( 
    TOP-REAL 2) 
    | P)) 
    = P by 
    PRE_TOPC:def 5;
    
      then
    
      
    
    A32: (( 
    TOP-REAL 2) 
    | P19) is 
    SubSpace of (( 
    TOP-REAL 2) 
    | P9) by 
    A3,
    A5,
    TOPMETR: 3,
    XBOOLE_1: 7;
    
      consider f1 be
    Function of 
    I[01] , (( 
    TOP-REAL 2) 
    | P1) such that 
    
      
    
    A33: f1 is 
    being_homeomorphism and 
    
      
    
    A34: (f1 
    .  
    0 ) 
    = p1 and 
    
      
    
    A35: (f1 
    . 1) 
    = p2 by 
    A1,
    TOPREAL1:def 1;
    
      
    
      
    
    A36: ( 
    dom f1) 
    = the 
    carrier of 
    I[01] by 
    FUNCT_2:def 1;
    
      P1
    c= P by 
    A3,
    XBOOLE_1: 7;
    
      then (
    rng f1) 
    c= the 
    carrier of (( 
    TOP-REAL 2) 
    | P) by 
    A5,
    A31;
    
      then
    
      reconsider ff1 = f1 as
    Function of 
    I[01] , (( 
    TOP-REAL 2) 
    | P9) by 
    A36,
    RELSET_1: 4;
    
      
    
      
    
    A37: ( 
    dom f1) 
    = the 
    carrier of 
    I[01] by 
    FUNCT_2:def 1;
    
      
    
      
    
    A38: 
    I[01] is 
    compact by 
    HEINE: 4,
    TOPMETR: 20;
    
      f1 is
    continuous by 
    A33;
    
      then
    
      
    
    A39: ff1 is 
    continuous by 
    A32,
    PRE_TOPC: 26;
    
      
    
      
    
    A40: f1 is 
    one-to-one by 
    A33;
    
      reconsider L1 = (
    L~ h1), L2 = ( 
    L~ h2) as non 
    empty  
    Subset of ( 
    TOP-REAL 2) by 
    A9;
    
      L1
    is_an_arc_of (p00,p11) by 
    A6,
    A10,
    A11,
    TOPREAL1: 25;
    
      then
    
      consider g1 be
    Function of 
    I[01] , (( 
    TOP-REAL 2) 
    | L1) such that 
    
      
    
    A41: g1 is 
    being_homeomorphism and 
    
      
    
    A42: (g1 
    .  
    0 ) 
    = p00 and 
    
      
    
    A43: (g1 
    . 1) 
    = p11 by 
    TOPREAL1:def 1;
    
      L2
    is_an_arc_of (p00,p11) by 
    A7,
    A12,
    A13,
    TOPREAL1: 25;
    
      then
    
      consider g2 be
    Function of 
    I[01] , (( 
    TOP-REAL 2) 
    | L2) such that 
    
      
    
    A44: g2 is 
    being_homeomorphism and 
    
      
    
    A45: (g2 
    .  
    0 ) 
    = p00 and 
    
      
    
    A46: (g2 
    . 1) 
    = p11 by 
    TOPREAL1:def 1;
    
      
    R^2-unit_square  
    = ( 
    [#] T) by 
    PRE_TOPC:def 5
    
      .= the
    carrier of T; 
    
      then
    
      reconsider p00, p11 as
    Point of T by 
    Lm28,
    Lm29,
    TOPREAL1: 14;
    
      
    
      
    
    A47: T is 
    T_2 by 
    TOPMETR: 2;
    
      set k1 = (ff1
    * (g1 
    " )), k2 = (ff2 
    * (g2 
    " )); 
    
      reconsider g1 as
    Function of 
    I[01] , (( 
    TOP-REAL 2) 
    | Lh1); 
    
      
    
      
    
    A48: g1 is 
    one-to-one by 
    A41;
    
      
    
      
    
    A49: ( 
    dom g1) 
    = the 
    carrier of 
    I[01] by 
    FUNCT_2:def 1;
    
      
    
      
    
    A50: ( 
    rng g1) 
    = ( 
    [#] T1) by 
    A41;
    
      then g1 is
    onto by 
    FUNCT_2:def 3;
    
      then
    
      
    
    A51: (g1 
    " ) 
    = (g1 qua 
    Function
    " ) by 
    A48,
    TOPS_2:def 4;
    
      then (
    rng (g1 
    " )) 
    = ( 
    dom g1) by 
    A48,
    FUNCT_1: 33;
    
      
    
      then
    
      
    
    A52: ( 
    rng k1) 
    = ( 
    rng f1) by 
    A37,
    A49,
    RELAT_1: 28
    
      .= P1 by
    A33,
    A5;
    
      
    
      
    
    A53: ( 
    dom g1) 
    = the 
    carrier of 
    I[01] by 
    FUNCT_2:def 1;
    
      then
    
      
    
    A54: 
    0  
    in ( 
    dom g1) by 
    BORSUK_1: 40,
    XXREAL_1: 1;
    
      then
    
      
    
    A55: 
    0  
    = ((g1 
    " ) 
    . p00) by 
    A42,
    A48,
    A51,
    FUNCT_1: 32;
    
      
    
      
    
    A56: ( 
    dom (g1 
    " )) 
    = ( 
    rng g1) by 
    A48,
    A51,
    FUNCT_1: 32;
    
      then
    
      
    
    A57: p00 
    in ( 
    dom (g1 
    " )) by 
    A42,
    A54,
    FUNCT_1:def 3;
    
      
    
      
    
    A58: 1 
    in ( 
    dom g1) by 
    A53,
    BORSUK_1: 40,
    XXREAL_1: 1;
    
      then
    
      
    
    A59: p11 
    in ( 
    dom (g1 
    " )) by 
    A43,
    A56,
    FUNCT_1:def 3;
    
      reconsider g2 as
    Function of 
    I[01] , (( 
    TOP-REAL 2) 
    | Lh2); 
    
      
    
      
    
    A60: g2 is 
    one-to-one by 
    A44;
    
      
    
      
    
    A61: ( 
    rng g2) 
    = ( 
    [#] T2) by 
    A44;
    
      then g2 is
    onto by 
    FUNCT_2:def 3;
    
      then
    
      
    
    A62: (g2 
    " ) 
    = (g2 qua 
    Function
    " ) by 
    A60,
    TOPS_2:def 4;
    
      g2 is
    continuous by 
    A44;
    
      then
    
      
    
    A63: T2 is 
    compact by 
    A38,
    A61,
    COMPTS_1: 14;
    
      
    
      
    
    A64: (g2 
    " ) is 
    continuous by 
    A44;
    
      g1 is
    continuous by 
    A41;
    
      then
    
      
    
    A65: T1 is 
    compact by 
    A38,
    A50,
    COMPTS_1: 14;
    
      
    
      
    
    A66: f2 is 
    one-to-one by 
    A23;
    
      
    
      
    
    A67: ( 
    dom g2) 
    = the 
    carrier of 
    I[01] by 
    FUNCT_2:def 1;
    
      then
    
      
    
    A68: 
    0  
    in ( 
    dom g2) by 
    BORSUK_1: 40,
    XXREAL_1: 1;
    
      then
    
      
    
    A69: p00 
    in ( 
    rng g2) by 
    A45,
    FUNCT_1:def 3;
    
      then
    
      
    
    A70: p00 
    in ( 
    dom (g2 
    " )) by 
    A60,
    A62,
    FUNCT_1: 32;
    
      ((g2
    " ) 
    . p00) 
    in ( 
    dom ff2) by 
    A45,
    A60,
    A62,
    A53,
    A67,
    A27,
    A54,
    FUNCT_1: 32;
    
      then
    
      
    
    A71: p00 
    in ( 
    dom (ff2 
    * (g2 
    " ))) by 
    A70,
    FUNCT_1: 11;
    
      
    
      
    
    A72: ( 
    dom ff1) 
    = the 
    carrier of 
    I[01] by 
    FUNCT_2:def 1;
    
      then ((g1
    " ) 
    . p00) 
    in ( 
    dom ff1) by 
    A42,
    A48,
    A51,
    A53,
    A54,
    FUNCT_1: 32;
    
      then p00
    in ( 
    dom (ff1 
    * (g1 
    " ))) by 
    A57,
    FUNCT_1: 11;
    
      
    
      then
    
      
    
    A73: (k1 
    . p00) 
    = (ff1 
    . ((g1 
    " ) 
    . p00)) by 
    FUNCT_1: 12
    
      .= p1 by
    A34,
    A42,
    A48,
    A51,
    A54,
    FUNCT_1: 32;
    
      
    
      then
    
      
    
    A74: (k1 
    . p00) 
    = (ff2 
    . ((g2 
    " ) 
    . p00)) by 
    A24,
    A45,
    A60,
    A62,
    A68,
    FUNCT_1: 32
    
      .= (k2
    . p00) by 
    A71,
    FUNCT_1: 12;
    
      
    
      
    
    A75: 1 
    in ( 
    dom g2) by 
    A67,
    BORSUK_1: 40,
    XXREAL_1: 1;
    
      then
    
      
    
    A76: 1 
    = ((g2 
    " ) 
    . p11) by 
    A46,
    A60,
    A62,
    FUNCT_1: 32;
    
      
    
      
    
    A77: ( 
    dom (g2 
    " )) 
    = ( 
    rng g2) by 
    A60,
    A62,
    FUNCT_1: 32;
    
      then
    
      
    
    A78: p11 
    in ( 
    dom (g2 
    " )) by 
    A46,
    A75,
    FUNCT_1:def 3;
    
      ((g2
    " ) 
    . p11) 
    in ( 
    dom ff2) by 
    A46,
    A60,
    A62,
    A53,
    A67,
    A27,
    A58,
    FUNCT_1: 32;
    
      then
    
      
    
    A79: p11 
    in ( 
    dom (ff2 
    * (g2 
    " ))) by 
    A78,
    FUNCT_1: 11;
    
      ((g1
    " ) 
    . p11) 
    in ( 
    dom ff1) by 
    A43,
    A48,
    A51,
    A53,
    A72,
    A58,
    FUNCT_1: 32;
    
      then p11
    in ( 
    dom (ff1 
    * (g1 
    " ))) by 
    A59,
    FUNCT_1: 11;
    
      
    
      then
    
      
    
    A80: (k1 
    . p11) 
    = (ff1 
    . ((g1 
    " ) 
    . p11)) by 
    FUNCT_1: 12
    
      .= p2 by
    A35,
    A43,
    A48,
    A51,
    A58,
    FUNCT_1: 32;
    
      
    
      then
    
      
    
    A81: (k1 
    . p11) 
    = (ff2 
    . ((g2 
    " ) 
    . p11)) by 
    A25,
    A46,
    A60,
    A62,
    A75,
    FUNCT_1: 32
    
      .= (k2
    . p11) by 
    A79,
    FUNCT_1: 12;
    
      (g1
    " ) is 
    continuous by 
    A41;
    
      then
    
      reconsider h = (k1
    +* k2) as 
    continuous  
    Function of T, (( 
    TOP-REAL 2) 
    | P) by 
    A8,
    A9,
    A39,
    A29,
    A18,
    A16,
    A15,
    A65,
    A63,
    A47,
    A64,
    A74,
    A81,
    A19,
    A17,
    COMPTS_1: 21;
    
      
    
      
    
    A82: 1 
    = ((g1 
    " ) 
    . p11) by 
    A43,
    A48,
    A51,
    A58,
    FUNCT_1: 32;
    
      
    
      
    
    A83: ( 
    rng (g2 
    " )) 
    = ( 
    dom g2) by 
    A60,
    A62,
    FUNCT_1: 33;
    
      
    
      then
    
      
    
    A84: ( 
    rng k2) 
    = ( 
    rng f2) by 
    A67,
    A27,
    RELAT_1: 28
    
      .= (
    [#] (( 
    TOP-REAL 2) 
    | P2)) by 
    A23
    
      .= P2 by
    PRE_TOPC:def 5;
    
      
    
      
    
    A85: 
    0  
    = ((g2 
    " ) 
    . p00) by 
    A45,
    A60,
    A62,
    A68,
    FUNCT_1: 32;
    
      now
    
        let x1,x2 be
    set;
    
        assume that
    
        
    
    A86: x1 
    in ( 
    dom k2) and 
    
        
    
    A87: x2 
    in (( 
    dom k1) 
    \ ( 
    dom k2)); 
    
        
    
        
    
    A88: x1 
    in ( 
    dom (g2 
    " )) by 
    A86,
    FUNCT_1: 11;
    
        
    
        
    
    A89: (k2 
    . x1) 
    in P2 by 
    A84,
    A86,
    FUNCT_1:def 3;
    
        
    
        
    
    A90: x2 
    in ( 
    dom k1) by 
    A87,
    XBOOLE_0:def 5;
    
        then
    
        
    
    A91: x2 
    in ( 
    dom (g1 
    " )) by 
    FUNCT_1: 11;
    
        assume
    
        
    
    A92: (k2 
    . x1) 
    = (k1 
    . x2); 
    
        then (k2
    . x1) 
    in P1 by 
    A52,
    A90,
    FUNCT_1:def 3;
    
        then
    
        
    
    A93: (k2 
    . x1) 
    in (P1 
    /\ P2) by 
    A89,
    XBOOLE_0:def 4;
    
        per cases by
    A4,
    A93,
    TARSKI:def 2;
    
          suppose
    
          
    
    A94: (k2 
    . x1) 
    = p1; 
    
          
    
          
    
    A95: ((g1 
    " ) 
    . x2) 
    in ( 
    dom ff1) by 
    A90,
    FUNCT_1: 11;
    
          p1
    = (ff1 
    . ((g1 
    " ) 
    . x2)) by 
    A92,
    A90,
    A94,
    FUNCT_1: 12;
    
          then
    
          
    
    A96: ((g1 
    " ) 
    . x2) 
    =  
    0 by 
    A34,
    A72,
    A28,
    A40,
    A95,
    FUNCT_1:def 4;
    
          
    
          
    
    A97: p00 
    in ( 
    dom (g2 
    " )) by 
    A60,
    A62,
    A69,
    FUNCT_1: 32;
    
          
    
          
    
    A98: ((g2 
    " ) 
    . x1) 
    in ( 
    dom ff2) by 
    A86,
    FUNCT_1: 11;
    
          p1
    = (ff2 
    . ((g2 
    " ) 
    . x1)) by 
    A86,
    A94,
    FUNCT_1: 12;
    
          then ((g2
    " ) 
    . x1) 
    =  
    0 by 
    A24,
    A28,
    A66,
    A98,
    FUNCT_1:def 4;
    
          then
    
          
    
    A99: x1 
    = p00 by 
    A60,
    A62,
    A85,
    A88,
    A97,
    FUNCT_1:def 4;
    
          p00
    in ( 
    dom (g1 
    " )) by 
    A42,
    A53,
    A28,
    A56,
    FUNCT_1:def 3;
    
          then x2
    in ( 
    dom k2) by 
    A48,
    A51,
    A55,
    A86,
    A91,
    A99,
    A96,
    FUNCT_1:def 4;
    
          hence contradiction by
    A87,
    XBOOLE_0:def 5;
    
        end;
    
          suppose
    
          
    
    A100: (k2 
    . x1) 
    = p2; 
    
          
    
          
    
    A101: ((g1 
    " ) 
    . x2) 
    in ( 
    dom ff1) by 
    A90,
    FUNCT_1: 11;
    
          p2
    = (ff1 
    . ((g1 
    " ) 
    . x2)) by 
    A92,
    A90,
    A100,
    FUNCT_1: 12;
    
          then
    
          
    
    A102: ((g1 
    " ) 
    . x2) 
    = 1 by 
    A35,
    A72,
    A30,
    A40,
    A101,
    FUNCT_1:def 4;
    
          
    
          
    
    A103: p11 
    in ( 
    dom (g2 
    " )) by 
    A46,
    A67,
    A77,
    A30,
    FUNCT_1:def 3;
    
          
    
          
    
    A104: ((g2 
    " ) 
    . x1) 
    in ( 
    dom ff2) by 
    A86,
    FUNCT_1: 11;
    
          p2
    = (ff2 
    . ((g2 
    " ) 
    . x1)) by 
    A86,
    A100,
    FUNCT_1: 12;
    
          then ((g2
    " ) 
    . x1) 
    = 1 by 
    A25,
    A30,
    A66,
    A104,
    FUNCT_1:def 4;
    
          then
    
          
    
    A105: x1 
    = p11 by 
    A60,
    A62,
    A76,
    A88,
    A103,
    FUNCT_1:def 4;
    
          p11
    in ( 
    dom (g1 
    " )) by 
    A43,
    A53,
    A56,
    A30,
    FUNCT_1:def 3;
    
          then x2
    in ( 
    dom k2) by 
    A48,
    A51,
    A82,
    A86,
    A91,
    A105,
    A102,
    FUNCT_1:def 4;
    
          hence contradiction by
    A87,
    XBOOLE_0:def 5;
    
        end;
    
      end;
    
      then
    
      
    
    A106: h is 
    one-to-one by 
    A48,
    A60,
    A62,
    A51,
    A40,
    A66,
    TOPMETR2: 1;
    
      
    
      
    
    A107: (( 
    TOP-REAL 2) 
    | P9) is 
    T_2 by 
    TOPMETR: 2;
    
      
    
      
    
    A108: ( 
    dom k2) 
    = ( 
    dom (g2 
    " )) by 
    A27,
    A83,
    RELAT_1: 27;
    
      (k1
    .: (( 
    dom k1) 
    /\ ( 
    dom k2))) 
    c= ( 
    rng k2) 
    
      proof
    
        let a be
    object;
    
        
    
        
    
    A109: ( 
    dom k2) 
    = the 
    carrier of T2 by 
    FUNCT_2:def 1;
    
        assume a
    in (k1 
    .: (( 
    dom k1) 
    /\ ( 
    dom k2))); 
    
        then
    
        
    
    A110: ex x be 
    object st x 
    in ( 
    dom k1) & x 
    in (( 
    dom k1) 
    /\ ( 
    dom k2)) & a 
    = (k1 
    . x) by 
    FUNCT_1:def 6;
    
        (
    dom k1) 
    = the 
    carrier of T1 by 
    FUNCT_2:def 1;
    
        then a
    = p1 or a 
    = p2 by 
    A9,
    A18,
    A16,
    A73,
    A80,
    A110,
    A109,
    TARSKI:def 2;
    
        hence thesis by
    A70,
    A73,
    A74,
    A78,
    A80,
    A81,
    A108,
    FUNCT_1:def 3;
    
      end;
    
      then
    
      
    
    A111: ( 
    rng h) 
    = ( 
    [#] (( 
    TOP-REAL 2) 
    | P9)) by 
    A3,
    A31,
    A52,
    A84,
    TOPMETR2: 2;
    
      reconsider h as
    Function of (( 
    TOP-REAL 2) 
    |  
    R^2-unit_square ), (( 
    TOP-REAL 2) 
    | P); 
    
      take h;
    
      T is
    compact by 
    Th2,
    COMPTS_1: 3;
    
      hence thesis by
    A107,
    A111,
    A106,
    COMPTS_1: 17;
    
    end;
    
    theorem :: 
    
    TOPREAL2:5
    
    
    
    
    
    Th5: for P be non 
    empty  
    Subset of ( 
    TOP-REAL 2) holds P is 
    being_simple_closed_curve iff (ex p1, p2 st p1 
    <> p2 & p1 
    in P & p2 
    in P) & for p1, p2 st p1 
    <> p2 & p1 
    in P & p2 
    in P holds ex P1,P2 be non 
    empty  
    Subset of ( 
    TOP-REAL 2) st P1 
    is_an_arc_of (p1,p2) & P2 
    is_an_arc_of (p1,p2) & P 
    = (P1 
    \/ P2) & (P1 
    /\ P2) 
    =  
    {p1, p2}
    
    proof
    
      let P be non
    empty  
    Subset of ( 
    TOP-REAL 2); 
    
      thus P is
    being_simple_closed_curve implies (ex p1, p2 st p1 
    <> p2 & p1 
    in P & p2 
    in P) & for p1, p2 st p1 
    <> p2 & p1 
    in P & p2 
    in P holds ex P1,P2 be non 
    empty  
    Subset of ( 
    TOP-REAL 2) st P1 
    is_an_arc_of (p1,p2) & P2 
    is_an_arc_of (p1,p2) & P 
    = (P1 
    \/ P2) & (P1 
    /\ P2) 
    =  
    {p1, p2}
    
      proof
    
        assume
    
        
    
    A1: P is 
    being_simple_closed_curve;
    
        then
    
        consider f be
    Function of (( 
    TOP-REAL 2) 
    |  
    R^2-unit_square ), (( 
    TOP-REAL 2) 
    | P) such that 
    
        
    
    A2: f is 
    being_homeomorphism;
    
        
    
        
    
    A3: ( 
    dom f) 
    = ( 
    [#] (( 
    TOP-REAL 2) 
    |  
    R^2-unit_square )) by 
    A2;
    
        
    
        
    
    A4: ( 
    [#] (( 
    TOP-REAL 2) 
    | P)) 
    c= ( 
    [#] ( 
    TOP-REAL 2)) by 
    PRE_TOPC:def 4;
    
        
    
        
    
    A5: f is 
    continuous by 
    A2;
    
        thus ex p1, p2 st p1
    <> p2 & p1 
    in P & p2 
    in P by 
    A1,
    Th4;
    
        set RS =
    R^2-unit_square ; 
    
        let p1, p2;
    
        assume that
    
        
    
    A6: p1 
    <> p2 and 
    
        
    
    A7: p1 
    in P and 
    
        
    
    A8: p2 
    in P; 
    
        
    
        
    
    A9: ( 
    [#] (( 
    TOP-REAL 2) 
    |  
    R^2-unit_square )) 
    =  
    R^2-unit_square by 
    PRE_TOPC:def 5;
    
        set q1 = ((f
    " ) 
    . p1), q2 = ((f 
    " ) 
    . p2); 
    
        
    
        
    
    A10: ( 
    [#] (( 
    TOP-REAL 2) 
    | RS)) 
    c= ( 
    [#] ( 
    TOP-REAL 2)) by 
    PRE_TOPC:def 4;
    
        
    
        
    
    A11: 
    I[01] is 
    compact by 
    HEINE: 4,
    TOPMETR: 20;
    
        
    
        
    
    A12: f is 
    one-to-one by 
    A2;
    
        
    
        
    
    A13: ( 
    rng f) 
    = ( 
    [#] (( 
    TOP-REAL 2) 
    | P)) by 
    A2;
    
        then f is
    onto by 
    FUNCT_2:def 3;
    
        then
    
        
    
    A14: (f 
    " ) 
    = (f qua 
    Function
    " ) by 
    A12,
    TOPS_2:def 4;
    
        then
    
        
    
    A15: ( 
    rng (f 
    " )) 
    = ( 
    dom f) by 
    A12,
    FUNCT_1: 33;
    
        
    
        
    
    A16: ( 
    dom (f 
    " )) 
    = ( 
    rng f) by 
    A12,
    A14,
    FUNCT_1: 32;
    
        then
    
        
    
    A17: p1 
    in ( 
    dom (f 
    " )) by 
    A7,
    A13,
    PRE_TOPC:def 5;
    
        
    
        
    
    A18: p2 
    in ( 
    dom (f 
    " )) by 
    A8,
    A13,
    A16,
    PRE_TOPC:def 5;
    
        reconsider f as
    Function of (( 
    TOP-REAL 2) 
    | RS), (( 
    TOP-REAL 2) 
    | P); 
    
        
    
        
    
    A19: q1 
    in ( 
    rng (f 
    " )) by 
    A17,
    FUNCT_1:def 3;
    
        
    
        
    
    A20: q2 
    in ( 
    rng (f 
    " )) by 
    A18,
    FUNCT_1:def 3;
    
        reconsider q1, q2 as
    Point of ( 
    TOP-REAL 2) by 
    A10,
    A19,
    A20;
    
        
    
        
    
    A21: q1 
    <> q2 by 
    A6,
    A12,
    A14,
    A17,
    A18,
    FUNCT_1:def 4;
    
        
    
        
    
    A22: ( 
    dom f) 
    = the 
    carrier of (( 
    TOP-REAL 2) 
    |  
    R^2-unit_square ) by 
    FUNCT_2:def 1;
    
        then
    
        
    
    A23: q2 
    in  
    R^2-unit_square by 
    A15,
    A18,
    A9,
    FUNCT_1:def 3;
    
        
    
        
    
    A24: p1 
    = (f 
    . q1) by 
    A12,
    A14,
    A16,
    A17,
    FUNCT_1: 35;
    
        q1
    in  
    R^2-unit_square by 
    A15,
    A17,
    A22,
    A9,
    FUNCT_1:def 3;
    
        then
    
        consider Q1,Q2 be non
    empty  
    Subset of ( 
    TOP-REAL 2) such that 
    
        
    
    A25: Q1 
    is_an_arc_of (q1,q2) and 
    
        
    
    A26: Q2 
    is_an_arc_of (q1,q2) and 
    
        
    
    A27: 
    R^2-unit_square  
    = (Q1 
    \/ Q2) and 
    
        
    
    A28: (Q1 
    /\ Q2) 
    =  
    {q1, q2} by
    A21,
    A23,
    Th1;
    
        
    
        
    
    A29: Q2 
    c= ( 
    dom f) by 
    A22,
    A9,
    A27,
    XBOOLE_1: 7;
    
        set P1 = (f
    .: Q1), P2 = (f 
    .: Q2); 
    
        Q1
    c= ( 
    dom f) by 
    A22,
    A9,
    A27,
    XBOOLE_1: 7;
    
        then
    
        reconsider P1, P2 as non
    empty  
    Subset of ( 
    TOP-REAL 2) by 
    A29,
    A4,
    XBOOLE_1: 1;
    
        
    
        
    
    A30: ( 
    rng (f 
    | Q1)) 
    = P1 by 
    RELAT_1: 115
    
        .= (
    [#] (( 
    TOP-REAL 2) 
    | P1)) by 
    PRE_TOPC:def 5
    
        .= the
    carrier of (( 
    TOP-REAL 2) 
    | P1); 
    
        (
    dom (f 
    | Q1)) 
    = ( 
    R^2-unit_square  
    /\ Q1) by 
    A22,
    A9,
    RELAT_1: 61
    
        .= Q1 by
    A27,
    XBOOLE_1: 21
    
        .= (
    [#] (( 
    TOP-REAL 2) 
    | Q1)) by 
    PRE_TOPC:def 5;
    
        then
    
        reconsider F1 = (f
    | Q1) as 
    Function of (( 
    TOP-REAL 2) 
    | Q1), (( 
    TOP-REAL 2) 
    | P1) by 
    A30,
    FUNCT_2:def 1,
    RELSET_1: 4;
    
        
    
        
    
    A31: (f 
    " P1) 
    c= Q1 by 
    A12,
    FUNCT_1: 82;
    
        (
    [#] (( 
    TOP-REAL 2) 
    | Q1)) 
    = Q1 by 
    PRE_TOPC:def 5;
    
        then
    
        
    
    A32: (( 
    TOP-REAL 2) 
    | Q1) is 
    SubSpace of (( 
    TOP-REAL 2) 
    |  
    R^2-unit_square ) by 
    A9,
    A27,
    TOPMETR: 3,
    XBOOLE_1: 7;
    
        Q1
    c= (f 
    " P1) by 
    A22,
    A9,
    A27,
    FUNCT_1: 76,
    XBOOLE_1: 7;
    
        then
    
        
    
    A33: (f 
    " P1) 
    = Q1 by 
    A31,
    XBOOLE_0:def 10;
    
        for R be
    Subset of (( 
    TOP-REAL 2) 
    | P1) st R is 
    closed holds (F1 
    " R) is 
    closed
    
        proof
    
          let R be
    Subset of (( 
    TOP-REAL 2) 
    | P1); 
    
          assume R is
    closed;
    
          then
    
          consider S1 be
    Subset of ( 
    TOP-REAL 2) such that 
    
          
    
    A34: S1 is 
    closed and 
    
          
    
    A35: R 
    = (S1 
    /\ ( 
    [#] (( 
    TOP-REAL 2) 
    | P1))) by 
    PRE_TOPC: 13;
    
          (S1
    /\ ( 
    rng f)) is 
    Subset of (( 
    TOP-REAL 2) 
    | P); 
    
          then
    
          reconsider S2 = ((
    rng f) 
    /\ S1) as 
    Subset of (( 
    TOP-REAL 2) 
    | P); 
    
          S2 is
    closed by 
    A13,
    A34,
    PRE_TOPC: 13;
    
          then
    
          
    
    A36: (f 
    " S2) is 
    closed by 
    A5;
    
          (F1
    " R) 
    = (Q1 
    /\ (f 
    " R)) by 
    FUNCT_1: 70
    
          .= (Q1
    /\ ((f 
    " S1) 
    /\ (f 
    " ( 
    [#] (( 
    TOP-REAL 2) 
    | P1))))) by 
    A35,
    FUNCT_1: 68
    
          .= (((f
    " S1) 
    /\ Q1) 
    /\ Q1) by 
    A33,
    PRE_TOPC:def 5
    
          .= ((f
    " S1) 
    /\ (Q1 
    /\ Q1)) by 
    XBOOLE_1: 16
    
          .= ((f
    " S1) 
    /\ ( 
    [#] (( 
    TOP-REAL 2) 
    | Q1))) by 
    PRE_TOPC:def 5
    
          .= ((f
    " (( 
    rng f) 
    /\ S1)) 
    /\ ( 
    [#] (( 
    TOP-REAL 2) 
    | Q1))) by 
    RELAT_1: 133;
    
          hence thesis by
    A32,
    A36,
    PRE_TOPC: 13;
    
        end;
    
        then
    
        
    
    A37: F1 is 
    continuous;
    
        reconsider Q19 = Q1, Q29 = Q2 as non
    empty  
    Subset of ( 
    TOP-REAL 2); 
    
        consider ff be
    Function of 
    I[01] , (( 
    TOP-REAL 2) 
    | Q1) such that 
    
        
    
    A38: ff is 
    being_homeomorphism and (ff 
    .  
    0 ) 
    = q1 and (ff 
    . 1) 
    = q2 by 
    A25,
    TOPREAL1:def 1;
    
        
    
        
    
    A39: ( 
    rng ff) 
    = ( 
    [#] (( 
    TOP-REAL 2) 
    | Q1)) by 
    A38;
    
        
    
        
    
    A40: ( 
    rng (f 
    | Q2)) 
    = P2 by 
    RELAT_1: 115
    
        .= (
    [#] (( 
    TOP-REAL 2) 
    | P2)) by 
    PRE_TOPC:def 5
    
        .= the
    carrier of (( 
    TOP-REAL 2) 
    | P2); 
    
        
    
        
    
    A41: p2 
    = (f 
    . q2) by 
    A12,
    A14,
    A16,
    A18,
    FUNCT_1: 35;
    
        (
    dom (f 
    | Q2)) 
    = ( 
    R^2-unit_square  
    /\ Q2) by 
    A22,
    A9,
    RELAT_1: 61
    
        .= Q2 by
    A27,
    XBOOLE_1: 21
    
        .= (
    [#] (( 
    TOP-REAL 2) 
    | Q2)) by 
    PRE_TOPC:def 5;
    
        then
    
        reconsider F2 = (f
    | Q2) as 
    Function of (( 
    TOP-REAL 2) 
    | Q2), (( 
    TOP-REAL 2) 
    | P2) by 
    A40,
    FUNCT_2:def 1,
    RELSET_1: 4;
    
        
    
        
    
    A42: (f 
    " P2) 
    c= Q2 by 
    A12,
    FUNCT_1: 82;
    
        (
    [#] (( 
    TOP-REAL 2) 
    | Q2)) 
    = Q2 by 
    PRE_TOPC:def 5;
    
        then
    
        
    
    A43: (( 
    TOP-REAL 2) 
    | Q2) is 
    SubSpace of (( 
    TOP-REAL 2) 
    |  
    R^2-unit_square ) by 
    A9,
    A27,
    TOPMETR: 3,
    XBOOLE_1: 7;
    
        Q2
    c= (f 
    " P2) by 
    A22,
    A9,
    A27,
    FUNCT_1: 76,
    XBOOLE_1: 7;
    
        then
    
        
    
    A44: (f 
    " P2) 
    = Q2 by 
    A42,
    XBOOLE_0:def 10;
    
        for R be
    Subset of (( 
    TOP-REAL 2) 
    | P2) st R is 
    closed holds (F2 
    " R) is 
    closed
    
        proof
    
          let R be
    Subset of (( 
    TOP-REAL 2) 
    | P2); 
    
          assume R is
    closed;
    
          then
    
          consider S1 be
    Subset of ( 
    TOP-REAL 2) such that 
    
          
    
    A45: S1 is 
    closed and 
    
          
    
    A46: R 
    = (S1 
    /\ ( 
    [#] (( 
    TOP-REAL 2) 
    | P2))) by 
    PRE_TOPC: 13;
    
          (S1
    /\ ( 
    rng f)) is 
    Subset of (( 
    TOP-REAL 2) 
    | P); 
    
          then
    
          reconsider S2 = ((
    rng f) 
    /\ S1) as 
    Subset of (( 
    TOP-REAL 2) 
    | P); 
    
          S2 is
    closed by 
    A13,
    A45,
    PRE_TOPC: 13;
    
          then
    
          
    
    A47: (f 
    " S2) is 
    closed by 
    A5;
    
          (F2
    " R) 
    = (Q2 
    /\ (f 
    " R)) by 
    FUNCT_1: 70
    
          .= (Q2
    /\ ((f 
    " S1) 
    /\ (f 
    " ( 
    [#] (( 
    TOP-REAL 2) 
    | P2))))) by 
    A46,
    FUNCT_1: 68
    
          .= (((f
    " S1) 
    /\ Q2) 
    /\ Q2) by 
    A44,
    PRE_TOPC:def 5
    
          .= ((f
    " S1) 
    /\ (Q2 
    /\ Q2)) by 
    XBOOLE_1: 16
    
          .= ((f
    " S1) 
    /\ ( 
    [#] (( 
    TOP-REAL 2) 
    | Q2))) by 
    PRE_TOPC:def 5
    
          .= ((f
    " (( 
    rng f) 
    /\ S1)) 
    /\ ( 
    [#] (( 
    TOP-REAL 2) 
    | Q2))) by 
    RELAT_1: 133;
    
          hence thesis by
    A43,
    A47,
    PRE_TOPC: 13;
    
        end;
    
        then
    
        
    
    A48: F2 is 
    continuous;
    
        
    
        
    
    A49: q2 
    in  
    {q1, q2} by
    TARSKI:def 2;
    
        
    
        
    
    A50: q1 
    in  
    {q1, q2} by
    TARSKI:def 2;
    
        
    
        
    
    A51: q1 
    in  
    {q1, q2} by
    TARSKI:def 2;
    
        
    {q1, q2}
    c= Q1 by 
    A28,
    XBOOLE_1: 17;
    
        then
    
        
    
    A52: q1 
    in (( 
    dom f) 
    /\ Q1) by 
    A15,
    A19,
    A51,
    XBOOLE_0:def 4;
    
        take P1, P2;
    
        
    
        
    
    A53: (( 
    TOP-REAL 2) 
    | P1) is 
    T_2 by 
    TOPMETR: 2;
    
        
    
        
    
    A54: q2 
    in  
    {q1, q2} by
    TARSKI:def 2;
    
        
    {q1, q2}
    c= Q1 by 
    A28,
    XBOOLE_1: 17;
    
        then
    
        
    
    A55: q2 
    in (( 
    dom f) 
    /\ Q1) by 
    A15,
    A20,
    A54,
    XBOOLE_0:def 4;
    
        
    
        
    
    A56: p2 
    = (f 
    . q2) by 
    A12,
    A14,
    A16,
    A18,
    FUNCT_1: 35
    
        .= (F1
    . q2) by 
    A55,
    FUNCT_1: 48;
    
        
    
        
    
    A57: ( 
    rng F1) 
    = ( 
    [#] (( 
    TOP-REAL 2) 
    | P1)) by 
    A30;
    
        ff is
    continuous by 
    A38;
    
        then
    
        
    
    A58: (( 
    TOP-REAL 2) 
    | Q19) is 
    compact by 
    A11,
    A39,
    COMPTS_1: 14;
    
        
    
        
    
    A59: F1 is 
    one-to-one by 
    A12,
    FUNCT_1: 52;
    
        p1
    = (f 
    . q1) by 
    A12,
    A14,
    A16,
    A17,
    FUNCT_1: 35
    
        .= (F1
    . q1) by 
    A52,
    FUNCT_1: 48;
    
        hence P1
    is_an_arc_of (p1,p2) by 
    A25,
    A57,
    A59,
    A37,
    A58,
    A53,
    A56,
    Th3,
    COMPTS_1: 17;
    
        
    
        
    
    A60: (( 
    TOP-REAL 2) 
    | P2) is 
    T_2 by 
    TOPMETR: 2;
    
        consider ff be
    Function of 
    I[01] , (( 
    TOP-REAL 2) 
    | Q2) such that 
    
        
    
    A61: ff is 
    being_homeomorphism and (ff 
    .  
    0 ) 
    = q1 and (ff 
    . 1) 
    = q2 by 
    A26,
    TOPREAL1:def 1;
    
        
    
        
    
    A62: ( 
    rng ff) 
    = ( 
    [#] (( 
    TOP-REAL 2) 
    | Q2)) by 
    A61;
    
        
    {q1, q2}
    c= Q2 by 
    A28,
    XBOOLE_1: 17;
    
        then q1
    in (( 
    dom f) 
    /\ Q2) by 
    A15,
    A19,
    A50,
    XBOOLE_0:def 4;
    
        then
    
        
    
    A63: p1 
    = (F2 
    . q1) by 
    A24,
    FUNCT_1: 48;
    
        
    
        
    
    A64: F2 is 
    one-to-one by 
    A12,
    FUNCT_1: 52;
    
        
    {q1, q2}
    c= Q2 by 
    A28,
    XBOOLE_1: 17;
    
        then q2
    in (( 
    dom f) 
    /\ Q2) by 
    A15,
    A20,
    A49,
    XBOOLE_0:def 4;
    
        then
    
        
    
    A65: p2 
    = (F2 
    . q2) by 
    A41,
    FUNCT_1: 48;
    
        ff is
    continuous by 
    A61;
    
        then
    
        
    
    A66: (( 
    TOP-REAL 2) 
    | Q29) is 
    compact by 
    A11,
    A62,
    COMPTS_1: 14;
    
        (
    rng F2) 
    = ( 
    [#] (( 
    TOP-REAL 2) 
    | P2)) by 
    A40;
    
        hence P2
    is_an_arc_of (p1,p2) by 
    A26,
    A64,
    A48,
    A66,
    A60,
    A63,
    A65,
    Th3,
    COMPTS_1: 17;
    
        (
    [#] (( 
    TOP-REAL 2) 
    | P)) 
    = P by 
    PRE_TOPC:def 5;
    
        
    
        hence P
    = (f 
    .: (Q1 
    \/ Q2)) by 
    A13,
    A3,
    A9,
    A27,
    RELAT_1: 113
    
        .= (P1
    \/ P2) by 
    RELAT_1: 120;
    
        
    
        thus (P1
    /\ P2) 
    = (f 
    .: (Q1 
    /\ Q2)) by 
    A12,
    FUNCT_1: 62
    
        .= (f
    .: ( 
    {q1}
    \/  
    {q2})) by
    A28,
    ENUMSET1: 1
    
        .= ((
    Im (f,q1)) 
    \/ ( 
    Im (f,q2))) by 
    RELAT_1: 120
    
        .= (
    {p1}
    \/ ( 
    Im (f,q2))) by 
    A15,
    A19,
    A24,
    FUNCT_1: 59
    
        .= (
    {p1}
    \/  
    {p2}) by
    A15,
    A20,
    A41,
    FUNCT_1: 59
    
        .=
    {p1, p2} by
    ENUMSET1: 1;
    
      end;
    
      given p1, p2 such that
    
      
    
    A67: p1 
    <> p2 and 
    
      
    
    A68: p1 
    in P and 
    
      
    
    A69: p2 
    in P; 
    
      assume for p1, p2 st p1
    <> p2 & p1 
    in P & p2 
    in P holds ex P1,P2 be non 
    empty  
    Subset of ( 
    TOP-REAL 2) st P1 
    is_an_arc_of (p1,p2) & P2 
    is_an_arc_of (p1,p2) & P 
    = (P1 
    \/ P2) & (P1 
    /\ P2) 
    =  
    {p1, p2};
    
      then ex P1,P2 be non
    empty  
    Subset of ( 
    TOP-REAL 2) st P1 
    is_an_arc_of (p1,p2) & P2 
    is_an_arc_of (p1,p2) & P 
    = (P1 
    \/ P2) & (P1 
    /\ P2) 
    =  
    {p1, p2} by
    A67,
    A68,
    A69;
    
      hence thesis by
    Lm34;
    
    end;
    
    theorem :: 
    
    TOPREAL2:6
    
    for P be non
    empty  
    Subset of ( 
    TOP-REAL 2) holds P is 
    being_simple_closed_curve iff ex p1,p2 be 
    Point of ( 
    TOP-REAL 2), P1,P2 be non 
    empty  
    Subset of ( 
    TOP-REAL 2) st p1 
    <> p2 & p1 
    in P & p2 
    in P & P1 
    is_an_arc_of (p1,p2) & P2 
    is_an_arc_of (p1,p2) & P 
    = (P1 
    \/ P2) & (P1 
    /\ P2) 
    =  
    {p1, p2}
    
    proof
    
      let P be non
    empty  
    Subset of ( 
    TOP-REAL 2); 
    
      hereby
    
        assume
    
        
    
    A1: P is 
    being_simple_closed_curve;
    
        then
    
        consider p1, p2 such that
    
        
    
    A2: p1 
    <> p2 and 
    
        
    
    A3: p1 
    in P and 
    
        
    
    A4: p2 
    in P by 
    Th5;
    
        consider P1,P2 be non
    empty  
    Subset of ( 
    TOP-REAL 2) such that 
    
        
    
    A5: P1 
    is_an_arc_of (p1,p2) and 
    
        
    
    A6: P2 
    is_an_arc_of (p1,p2) and 
    
        
    
    A7: P 
    = (P1 
    \/ P2) and 
    
        
    
    A8: (P1 
    /\ P2) 
    =  
    {p1, p2} by
    A1,
    A2,
    A3,
    A4,
    Th5;
    
        take p1, p2, P1, P2;
    
        thus p1
    <> p2 & p1 
    in P & p2 
    in P & P1 
    is_an_arc_of (p1,p2) & P2 
    is_an_arc_of (p1,p2) & P 
    = (P1 
    \/ P2) & (P1 
    /\ P2) 
    =  
    {p1, p2} by
    A2,
    A3,
    A4,
    A5,
    A6,
    A7,
    A8;
    
      end;
    
      thus thesis by
    Lm34;
    
    end;
    
    
    
    
    
    Lm35: for S be 
    1-sorted, T be 
    1-sorted, f be 
    Function of S, T st S is 
    empty & ( 
    rng f) 
    = ( 
    [#] T) holds T is 
    empty
    
    proof
    
      let S be
    1-sorted, T be 
    1-sorted, f be 
    Function of S, T such that 
    
      
    
    A1: S is 
    empty and 
    
      
    
    A2: ( 
    rng f) 
    = ( 
    [#] T); 
    
      assume T is non
    empty;
    
      then
    
      reconsider T as non
    empty  
    1-sorted;
    
      consider y be
    object such that 
    
      
    
    A3: y 
    in the 
    carrier of T by 
    XBOOLE_0:def 1;
    
      ex x be
    object st x 
    in ( 
    dom f) & (f 
    . x) 
    = y by 
    A2,
    A3,
    FUNCT_1:def 3;
    
      hence contradiction by
    A1;
    
    end;
    
    
    
    
    
    Lm36: for S be 
    1-sorted, T be 
    1-sorted, f be 
    Function of S, T st T is 
    empty & ( 
    dom f) 
    = ( 
    [#] S) holds S is 
    empty
    
    proof
    
      let S be
    1-sorted, T be 
    1-sorted, f be 
    Function of S, T such that 
    
      
    
    A1: T is 
    empty and 
    
      
    
    A2: ( 
    dom f) 
    = ( 
    [#] S); 
    
      assume S is non
    empty;
    
      then
    
      reconsider S as non
    empty  
    1-sorted;
    
      consider x be
    object such that 
    
      
    
    A3: x 
    in the 
    carrier of S by 
    XBOOLE_0:def 1;
    
      (f
    . x) 
    in ( 
    rng f) by 
    A2,
    A3,
    FUNCT_1:def 3;
    
      hence thesis by
    A1;
    
    end;
    
    
    
    
    
    Lm37: for S,T be 
    TopStruct st ex f be 
    Function of S, T st f is 
    being_homeomorphism holds S is 
    empty iff T is 
    empty by 
    Lm35,
    Lm36;
    
    registration
    
      cluster 
    being_simple_closed_curve -> non 
    empty
    compact for 
    Subset of ( 
    TOP-REAL 2); 
    
      coherence
    
      proof
    
        let P be
    Subset of ( 
    TOP-REAL 2); 
    
        given f be
    Function of (( 
    TOP-REAL 2) 
    |  
    R^2-unit_square ), (( 
    TOP-REAL 2) 
    | P) such that 
    
        
    
    A1: f is 
    being_homeomorphism;
    
        thus P is non
    empty by 
    A1,
    Lm37;
    
        
    
        
    
    A2: ( 
    rng f) 
    = ( 
    [#] (( 
    TOP-REAL 2) 
    | P)) by 
    A1;
    
        reconsider R = P as non
    empty  
    Subset of ( 
    TOP-REAL 2) by 
    A1,
    Lm37;
    
        
    
        
    
    A3: f is 
    continuous by 
    A1;
    
        ((
    TOP-REAL 2) 
    |  
    R^2-unit_square ) is 
    compact by 
    Th2,
    COMPTS_1: 3;
    
        then ((
    TOP-REAL 2) 
    | R) is 
    compact by 
    A3,
    A2,
    COMPTS_1: 14;
    
        hence thesis by
    COMPTS_1: 3;
    
      end;
    
    end