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