bkmodel4.miz



    begin

    theorem :: BKMODEL4:1

    

     Th25: for a,b be Real st a <> b holds (1 - (a / (a - b))) = ( - (b / (a - b)))

    proof

      let a,b be Real;

      assume a <> b;

      then (a - b) <> 0 ;

      

      then (1 - (a / (a - b))) = (((a - b) / (a - b)) - (a / (a - b))) by XCMPLX_1: 60

      .= (((a - b) - a) / (a - b));

      hence thesis;

    end;

    theorem :: BKMODEL4:2

    for a,b be Real st 0 < (a * b) holds 0 < (a / b)

    proof

      let a,b be Real;

      assume

       A1: 0 < (a * b);

      then

       A2: b <> 0 ;

      then 0 < (b ^2 ) by SQUARE_1: 12;

      then ( 0 / (b ^2 )) < ((a * b) / (b ^2 )) by A1;

      then 0 < ((a * b) / (b * b)) by SQUARE_1:def 1;

      then 0 < ((a / b) * (b / b)) by XCMPLX_1: 76;

      then 0 < ((a / b) * 1) by A2, XCMPLX_1: 60;

      hence thesis;

    end;

    theorem :: BKMODEL4:3

    

     Th31: for a,b,c be Real st 0 <= a <= 1 & 0 < (b * c) holds 0 <= ((a * c) / (((1 - a) * b) + (a * c))) <= 1

    proof

      let a,b,c be Real;

      assume that

       A1: 0 <= a <= 1 and

       A2: 0 < (b * c);

      per cases by A2, XREAL_1: 134;

        suppose

         A3: 0 < b & 0 < c;

        

         B3: (a - a) <= (1 - a) by A1, XREAL_1: 9;

        hence 0 <= ((a * c) / (((1 - a) * b) + (a * c))) by A1, A3;

        ( 0 + (a * c)) <= (((1 - a) * b) + (a * c)) by A3, B3, XREAL_1: 6;

        hence ((a * c) / (((1 - a) * b) + (a * c))) <= 1 by A1, A3, XREAL_1: 183;

      end;

        suppose

         A4: b < 0 & c < 0 ;

        

         A5: (a - a) <= (1 - a) by A1, XREAL_1: 9;

        hence 0 <= ((a * c) / (((1 - a) * b) + (a * c))) by A1, A4;

        (((1 - a) * b) + (a * c)) <= ( 0 + (a * c)) by A4, A5, XREAL_1: 6;

        hence ((a * c) / (((1 - a) * b) + (a * c))) <= 1 by A1, A4, XREAL_1: 184;

      end;

    end;

    theorem :: BKMODEL4:4

    

     Th32: for a,b,c be Real st (((1 - a) * b) + (a * c)) <> 0 holds (1 - ((a * c) / (((1 - a) * b) + (a * c)))) = (((1 - a) * b) / (((1 - a) * b) + (a * c)))

    proof

      let a,b,c be Real;

      set r = (((1 - a) * b) + (a * c));

      assume (((1 - a) * b) + (a * c)) <> 0 ;

      

      then (1 - ((a * c) / r)) = ((r / r) - ((a * c) / r)) by XCMPLX_1: 60

      .= (((1 - a) * b) / r);

      hence thesis;

    end;

    theorem :: BKMODEL4:5

    

     Th33: for a,b,c,d be Real st b <> 0 holds ((((a * b) / c) * d) / b) = ((a * d) / c)

    proof

      let a,b,c,d be Real;

      assume

       A1: b <> 0 ;

      ((((a * b) / c) * d) / b) = (a * ((d / c) * (b / b)))

      .= (a * ((d / c) * 1)) by A1, XCMPLX_1: 60;

      hence thesis;

    end;

    theorem :: BKMODEL4:6

    

     Th35: for u be Element of ( TOP-REAL 3) holds u = |[(u . 1), (u . 2), (u . 3)]|

    proof

      let u be Element of ( TOP-REAL 3);

      

      thus u = |[(u `1 ), (u `2 ), (u `3 )]| by EUCLID_5: 3

      .= |[(u . 1), (u `2 ), (u `3 )]| by EUCLID_5:def 1

      .= |[(u . 1), (u . 2), (u `3 )]| by EUCLID_5:def 2

      .= |[(u . 1), (u . 2), (u . 3)]| by EUCLID_5:def 3;

    end;

    theorem :: BKMODEL4:7

    

     Th01: for P be Element of BK_model holds ( BK_to_REAL2 P) in TarskiEuclid2Space

    proof

      let P be Element of BK_model ;

       the MetrStruct of TarskiEuclid2Space = the MetrStruct of ( Euclid 2) & ( BK_to_REAL2 P) in ( TOP-REAL 2) by GTARSKI1:def 13;

      hence thesis by EUCLID: 22;

    end;

    definition

      let P be POINT of BK-model-Plane ;

      :: BKMODEL4:def1

      func BK_to_T2 P -> POINT of TarskiEuclid2Space means

      : Def01: ex p be Element of BK_model st P = p & it = ( BK_to_REAL2 p);

      existence

      proof

        reconsider p = P as Element of BK_model ;

        ( BK_to_REAL2 p) in TarskiEuclid2Space by Th01;

        hence thesis;

      end;

      uniqueness ;

    end

    definition

      let P be POINT of TarskiEuclid2Space ;

      assume

       A1: ( Tn2TR P) in ( inside_of_circle ( 0 , 0 ,1));

      :: BKMODEL4:def2

      func T2_to_BK P -> POINT of BK-model-Plane means

      : Def02: ex u be non zero Element of ( TOP-REAL 3) st it = ( Dir u) & (u `3 ) = 1 & ( Tn2TR P) = |[(u `1 ), (u `2 )]|;

      existence

      proof

        reconsider p = ( Tn2TR P) as Element of ( inside_of_circle ( 0 , 0 ,1)) by A1;

        reconsider Q = ( REAL2_to_BK p) as Element of BK_model ;

        consider P2 be Element of ( TOP-REAL 2) such that

         A2: P2 = p and

         A3: ( REAL2_to_BK p) = ( Dir |[(P2 `1 ), (P2 `2 ), 1]|) by BKMODEL2:def 3;

        reconsider u = |[(P2 `1 ), (P2 `2 ), 1]| as non zero Element of ( TOP-REAL 3);

        now

          thus Q = ( Dir u) by A3;

           |[(u `1 ), (u `2 ), (u `3 )]| = |[(P2 `1 ), (P2 `2 ), 1]| by EUCLID_5: 3;

          then

           A4: (u `1 ) = (P2 `1 ) & (u `2 ) = (P2 `2 ) & (u `3 ) = 1 by FINSEQ_1: 78;

          thus (u `3 ) = 1 by EUCLID_5: 2;

          thus p = |[(u `1 ), (u `2 )]| by A2, A4, EUCLID: 53;

        end;

        hence thesis;

      end;

      uniqueness

      proof

        let P1,P2 be POINT of BK-model-Plane such that

         A5: ex u be non zero Element of ( TOP-REAL 3) st P1 = ( Dir u) & (u `3 ) = 1 & ( Tn2TR P) = |[(u `1 ), (u `2 )]| and

         A6: ex v be non zero Element of ( TOP-REAL 3) st P2 = ( Dir v) & (v `3 ) = 1 & ( Tn2TR P) = |[(v `1 ), (v `2 )]|;

        consider u be non zero Element of ( TOP-REAL 3) such that

         A7: P1 = ( Dir u) and

         A8: (u `3 ) = 1 and

         A9: ( Tn2TR P) = |[(u `1 ), (u `2 )]| by A5;

        consider v be non zero Element of ( TOP-REAL 3) such that

         A10: P2 = ( Dir v) and

         A11: (v `3 ) = 1 and

         A12: ( Tn2TR P) = |[(v `1 ), (v `2 )]| by A6;

        

         A13: (u `1 ) = (v `1 ) & (u `2 ) = (v `2 ) by A9, A12, FINSEQ_1: 77;

        u = |[(v `1 ), (v `2 ), (v `3 )]| by A13, A8, A11, EUCLID_5: 3

        .= v by EUCLID_5: 3;

        hence thesis by A7, A10;

      end;

    end

    theorem :: BKMODEL4:8

    

     Th02: for P be POINT of BK-model-Plane holds ( Tn2TR ( BK_to_T2 P)) in ( inside_of_circle ( 0 , 0 ,1))

    proof

      let P be POINT of BK-model-Plane ;

      consider p be Element of BK_model such that P = p and

       A1: ( BK_to_T2 P) = ( BK_to_REAL2 p) by Def01;

      reconsider Q = ( BK_to_T2 P) as POINT of TarskiEuclid2Space ;

      thus thesis by A1;

    end;

    theorem :: BKMODEL4:9

    for P be POINT of BK-model-Plane holds ( T2_to_BK ( BK_to_T2 P)) = P

    proof

      let P be POINT of BK-model-Plane ;

      consider p be Element of BK_model such that

       A1: P = p and

       A2: ( BK_to_T2 P) = ( BK_to_REAL2 p) by Def01;

      consider u be non zero Element of ( TOP-REAL 3) such that

       A3: ( Dir u) = p and

       A4: (u . 3) = 1 and

       A5: ( BK_to_REAL2 p) = |[(u . 1), (u . 2)]| by BKMODEL2:def 2;

      reconsider Q = ( BK_to_T2 P) as POINT of TarskiEuclid2Space ;

      consider v be non zero Element of ( TOP-REAL 3) such that

       A6: ( T2_to_BK Q) = ( Dir v) and

       A7: (v `3 ) = 1 and

       A8: ( Tn2TR Q) = |[(v `1 ), (v `2 )]| by A2, Def02;

      (u . 1) = (v `1 ) & (u . 2) = (v `2 ) by A8, A5, A2, FINSEQ_1: 77;

      then

       A9: (u `1 ) = (v `1 ) & (u `2 ) = (v `2 ) by EUCLID_5:def 1, EUCLID_5:def 2;

      u = |[(u `1 ), (u `2 ), (u `3 )]| by EUCLID_5: 3

      .= |[(v `1 ), (v `2 ), (v `3 )]| by A4, A7, A9, EUCLID_5:def 3

      .= v by EUCLID_5: 3;

      hence thesis by A1, A6, A3;

    end;

    theorem :: BKMODEL4:10

    

     Th03: for P be POINT of TarskiEuclid2Space st ( Tn2TR P) is Element of ( inside_of_circle ( 0 , 0 ,1)) holds ( BK_to_T2 ( T2_to_BK P)) = P

    proof

      let P be POINT of TarskiEuclid2Space ;

      assume ( Tn2TR P) is Element of ( inside_of_circle ( 0 , 0 ,1));

      then

      consider u be non zero Element of ( TOP-REAL 3) such that

       A1: ( T2_to_BK P) = ( Dir u) and

       A2: (u `3 ) = 1 and

       A3: ( Tn2TR P) = |[(u `1 ), (u `2 )]| by Def02;

      reconsider Q9 = ( T2_to_BK P) as Element of BK-model-Plane ;

      reconsider Q = ( T2_to_BK P) as Element of BK_model ;

      consider p be Element of BK_model such that

       A4: Q9 = p and

       A5: ( BK_to_T2 Q9) = ( BK_to_REAL2 p) by Def01;

      consider v be non zero Element of ( TOP-REAL 3) such that

       A6: ( Dir v) = p and

       A7: (v . 3) = 1 and

       A8: ( BK_to_REAL2 p) = |[(v . 1), (v . 2)]| by BKMODEL2:def 2;

       are_Prop (u,v) by A4, A6, A1, ANPROJ_1: 22;

      then

      consider a be Real such that a <> 0 and

       A9: u = (a * v) by ANPROJ_1: 1;

      

       A10: 1 = (a * (v `3 )) by A2, A9, EUCLID_5: 9

      .= (a * 1) by A7, EUCLID_5:def 3

      .= a;

       |[(u `1 ), (u `2 ), (u `3 )]| = u by EUCLID_5: 3

      .= |[(1 * (v `1 )), (1 * (v `2 )), (1 * (v `3 ))]| by A9, A10, EUCLID_5: 7;

      then (u `1 ) = (v `1 ) & (u `2 ) = (v `2 ) by FINSEQ_1: 78;

      then (u `1 ) = (v . 1) & (u `2 ) = (v . 2) by EUCLID_5:def 1, EUCLID_5:def 2;

      hence thesis by A5, A8, A3;

    end;

    theorem :: BKMODEL4:11

    

     Th04: for P be Point of BK-model-Plane holds for p be Element of BK_model st P = p holds ( BK_to_T2 P) = ( BK_to_REAL2 p) & ( Tn2TR ( BK_to_T2 P)) = ( BK_to_REAL2 p)

    proof

      let P be Point of BK-model-Plane ;

      let p be Element of BK_model ;

      assume

       A1: P = p;

      ex p be Element of BK_model st P = p & ( BK_to_T2 P) = ( BK_to_REAL2 p) by Def01;

      hence thesis by A1;

    end;

    theorem :: BKMODEL4:12

    

     Th05: for P,Q,R be Point of BK-model-Plane holds for P2,Q2,R2 be POINT of TarskiEuclid2Space st P2 = ( BK_to_T2 P) & Q2 = ( BK_to_T2 Q) & R2 = ( BK_to_T2 R) holds between (P,Q,R) iff between (P2,Q2,R2)

    proof

      let P,Q,R be Point of BK-model-Plane ;

      let P2,Q2,R2 be POINT of TarskiEuclid2Space ;

      assume that

       A1: P2 = ( BK_to_T2 P) and

       A2: Q2 = ( BK_to_T2 Q) and

       A3: R2 = ( BK_to_T2 R);

      reconsider p = P, q = Q, r = R as Element of BK_model ;

      

       A4: ( Tn2TR ( BK_to_T2 P)) = ( BK_to_REAL2 p) & ( Tn2TR ( BK_to_T2 Q)) = ( BK_to_REAL2 q) & ( Tn2TR ( BK_to_T2 R)) = ( BK_to_REAL2 r) by Th04;

      hereby

        assume between (P,Q,R);

        then ( BK_to_REAL2 q) in ( LSeg (( BK_to_REAL2 p),( BK_to_REAL2 r))) by BKMODEL3:def 7;

        hence between (P2,Q2,R2) by A4, A1, A2, A3, GTARSKI2: 20;

      end;

      assume between (P2,Q2,R2);

      then ( Tn2TR ( BK_to_T2 Q)) in ( LSeg (( Tn2TR ( BK_to_T2 P)),( Tn2TR ( BK_to_T2 R)))) by A1, A2, A3, GTARSKI2: 20;

      hence between (P,Q,R) by A4, BKMODEL3:def 7;

    end;

    theorem :: BKMODEL4:13

    

     Th06: for P,Q be Element of ( TOP-REAL 2) st P <> Q holds (P . 1) <> (Q . 1) or (P . 2) <> (Q . 2)

    proof

      let P,Q be Element of ( TOP-REAL 2);

      assume

       A1: P <> Q;

      assume (P . 1) = (Q . 1) & (P . 2) = (Q . 2);

      then (P `1 ) = (Q `1 ) & (P `2 ) = (Q `2 );

      

      then P = |[(Q `1 ), (Q `2 )]| by EUCLID: 53

      .= Q by EUCLID: 53;

      hence contradiction by A1;

    end;

    theorem :: BKMODEL4:14

    

     Th07: for a,b be Real holds for P,Q be Element of ( TOP-REAL 2) st P <> Q & (((1 - a) * P) + (a * Q)) = (((1 - b) * P) + (b * Q)) holds a = b

    proof

      let a,b be Real;

      let P,Q be Element of ( TOP-REAL 2);

      assume that

       A1: P <> Q and

       A2: (((1 - a) * P) + (a * Q)) = (((1 - b) * P) + (b * Q));

      reconsider PR2 = P, QR2 = Q as Element of ( REAL 2) by EUCLID: 22;

      reconsider R2 = (((1 - a) * PR2) + (a * QR2)) as Element of ( TOP-REAL 2) by EUCLID: 22;

      per cases by A1, Th06;

        suppose (P . 1) <> (Q . 1);

        then

         A3: ((QR2 . 1) - (PR2 . 1)) <> 0 ;

         0 = ((R2 . 1) - (R2 . 1))

        .= ((R2 - R2) . 1) by RVSUM_1: 27

        .= (((b - a) * (QR2 - PR2)) . 1) by A2, EUCLID12: 1

        .= ((b - a) * ((QR2 - PR2) . 1)) by RVSUM_1: 44

        .= ((b - a) * ((QR2 . 1) - (PR2 . 1))) by RVSUM_1: 27;

        then (b - a) = 0 by A3;

        hence thesis;

      end;

        suppose (P . 2) <> (Q . 2);

        then

         A4: ((QR2 . 2) - (PR2 . 2)) <> 0 ;

         0 = ((R2 . 2) - (R2 . 2))

        .= ((R2 - R2) . 2) by RVSUM_1: 27

        .= (((b - a) * (QR2 - PR2)) . 2) by A2, EUCLID12: 1

        .= ((b - a) * ((QR2 - PR2) . 2)) by RVSUM_1: 44

        .= ((b - a) * ((QR2 . 2) - (PR2 . 2))) by RVSUM_1: 27;

        then (b - a) = 0 by A4;

        hence thesis;

      end;

    end;

    theorem :: BKMODEL4:15

    

     Th08: for P,Q be Point of BK-model-Plane st ( Tn2TR ( BK_to_T2 P)) = ( Tn2TR ( BK_to_T2 Q)) holds P = Q

    proof

      let P,Q be Point of BK-model-Plane ;

      assume

       A1: ( Tn2TR ( BK_to_T2 P)) = ( Tn2TR ( BK_to_T2 Q));

      reconsider p = P, q = Q as Element of BK_model ;

      ( Tn2TR ( BK_to_T2 P)) = ( BK_to_REAL2 p) & ( Tn2TR ( BK_to_T2 Q)) = ( BK_to_REAL2 q) by Th04;

      hence thesis by A1, BKMODEL2: 4;

    end;

    definition

      let P,Q,R be Point of BK-model-Plane ;

      assume that

       A1: between (P,Q,R) and

       A2: P <> R;

      :: BKMODEL4:def3

      func length (P,Q,R) -> Real means

      : Def03: 0 <= it <= 1 & ( Tn2TR ( BK_to_T2 Q)) = (((1 - it ) * ( Tn2TR ( BK_to_T2 P))) + (it * ( Tn2TR ( BK_to_T2 R))));

      existence

      proof

        reconsider P2 = ( BK_to_T2 P), Q2 = ( BK_to_T2 Q), R2 = ( BK_to_T2 R) as Point of TarskiEuclid2Space ;

        reconsider p = P, q = Q, r = R as Element of BK_model ;

        ( BK_to_T2 P) = ( BK_to_REAL2 p) & ( Tn2TR ( BK_to_T2 P)) = ( BK_to_REAL2 p) & ( BK_to_T2 Q) = ( BK_to_REAL2 q) & ( Tn2TR ( BK_to_T2 Q)) = ( BK_to_REAL2 q) & ( BK_to_T2 R) = ( BK_to_REAL2 r) & ( Tn2TR ( BK_to_T2 R)) = ( BK_to_REAL2 r) by Th04;

        then ( Tn2TR ( BK_to_T2 Q)) in ( LSeg (( Tn2TR ( BK_to_T2 P)),( Tn2TR ( BK_to_T2 R)))) by A1, BKMODEL3:def 7;

        then

        consider r be Real such that

         A3: 0 <= r and

         A4: r <= 1 and

         A5: ( Tn2TR ( BK_to_T2 Q)) = (((1 - r) * ( Tn2TR ( BK_to_T2 P))) + (r * ( Tn2TR ( BK_to_T2 R)))) by RLTOPSP1: 76;

        take r;

        thus thesis by A3, A4, A5;

      end;

      uniqueness by A2, Th07, Th08;

    end

    theorem :: BKMODEL4:16

    

     Th09: for P,Q be Point of BK-model-Plane holds between (P,P,Q) & between (P,Q,Q)

    proof

      let P,Q be Point of BK-model-Plane ;

      reconsider P2 = ( BK_to_T2 P), Q2 = ( BK_to_T2 Q) as Point of TarskiEuclid2Space ;

       between (P2,P2,Q2) by GTARSKI1: 17;

      hence between (P,P,Q) by Th05;

       between (P2,Q2,Q2) by GTARSKI1: 14;

      hence between (P,Q,Q) by Th05;

    end;

    theorem :: BKMODEL4:17

    for P,Q be Point of BK-model-Plane st P <> Q holds ( length (P,P,Q)) = 0 & ( length (P,Q,Q)) = 1

    proof

      let P,Q be Point of BK-model-Plane ;

      assume

       A1: P <> Q;

      reconsider P2 = ( BK_to_T2 P), Q2 = ( BK_to_T2 Q) as Point of TarskiEuclid2Space ;

      

       A2: between (P,P,Q) by Th09;

      

       A3: between (P,Q,Q) by Th09;

      reconsider r = 0 as Real;

      now

        thus 0 <= r <= 1;

        

        thus (((1 - r) * ( Tn2TR ( BK_to_T2 P))) + (r * ( Tn2TR ( BK_to_T2 Q)))) = ( |[(1 * (( Tn2TR ( BK_to_T2 P)) `1 )), (1 * (( Tn2TR ( BK_to_T2 P)) `2 ))]| + ( 0 * ( Tn2TR ( BK_to_T2 Q)))) by EUCLID: 57

        .= ( |[(( Tn2TR ( BK_to_T2 P)) `1 ), (( Tn2TR ( BK_to_T2 P)) `2 )]| + |[( 0 * (( Tn2TR ( BK_to_T2 Q)) `1 )), ( 0 * (( Tn2TR ( BK_to_T2 Q)) `2 ))]|) by EUCLID: 57

        .= |[((( Tn2TR ( BK_to_T2 P)) `1 ) + 0 ), ((( Tn2TR ( BK_to_T2 P)) `2 ) + 0 )]| by EUCLID: 56

        .= ( Tn2TR ( BK_to_T2 P)) by EUCLID: 53;

      end;

      hence ( length (P,P,Q)) = 0 by A1, A2, Def03;

      reconsider s = 1 as Real;

      now

        thus 0 <= s <= 1;

        

        thus (((1 - s) * ( Tn2TR ( BK_to_T2 P))) + (s * ( Tn2TR ( BK_to_T2 Q)))) = ( |[(1 * (( Tn2TR ( BK_to_T2 Q)) `1 )), (1 * (( Tn2TR ( BK_to_T2 Q)) `2 ))]| + ( 0 * ( Tn2TR ( BK_to_T2 P)))) by EUCLID: 57

        .= ( |[(( Tn2TR ( BK_to_T2 Q)) `1 ), (( Tn2TR ( BK_to_T2 Q)) `2 )]| + |[( 0 * (( Tn2TR ( BK_to_T2 P)) `1 )), ( 0 * (( Tn2TR ( BK_to_T2 P)) `2 ))]|) by EUCLID: 57

        .= |[((( Tn2TR ( BK_to_T2 Q)) `1 ) + 0 ), ((( Tn2TR ( BK_to_T2 Q)) `2 ) + 0 )]| by EUCLID: 56

        .= ( Tn2TR ( BK_to_T2 Q)) by EUCLID: 53;

      end;

      hence ( length (P,Q,Q)) = 1 by A1, A3, Def03;

    end;

    theorem :: BKMODEL4:18

    for N be Matrix of 3, F_Real st N = <* <*2, 0 , ( - 1)*>, <* 0 , ( sqrt 3), 0 *>, <*1, 0 , ( - 2)*>*> holds ( Det N) = (( - 3) * ( sqrt 3)) & N is invertible

    proof

      let N be Matrix of 3, F_Real ;

      assume

       A1: N = <* <*2, 0 , ( - 1)*>, <* 0 , ( sqrt 3), 0 *>, <*1, 0 , ( - 2)*>*>;

      reconsider a = 2, b = 0 , c = ( - 1), d = 0 , e = ( sqrt 3), f = 0 , g = 1, h = 0 , i = ( - 2) as Element of F_Real by XREAL_0:def 1;

      ( Det N) = (((((((a * e) * i) - ((c * e) * g)) - ((a * f) * h)) + ((b * f) * g)) - ((b * d) * i)) + ((c * d) * h)) by A1, MATRIX_9: 46;

      then ( Det N) = (( - 3) * ( sqrt 3)) & ( Det N) <> ( 0. F_Real ) by SQUARE_1: 24;

      hence thesis by LAPLACE: 34;

    end;

    theorem :: BKMODEL4:19

    

     Th10: for a11,a12,a13,a21,a22,a23,a31,a32,a33,b11,b12,b13,b21,b22,b23,b31,b32,b33,ab11,ab12,ab13,ab21,ab22,ab23,ab31,ab32,ab33 be Element of F_Real holds for A,B be Matrix of 3, F_Real st A = <* <*a11, a12, a13*>, <*a21, a22, a23*>, <*a31, a32, a33*>*> & B = <* <*b11, b12, b13*>, <*b21, b22, b23*>, <*b31, b32, b33*>*> & ab11 = (((a11 * b11) + (a12 * b21)) + (a13 * b31)) & ab12 = (((a11 * b12) + (a12 * b22)) + (a13 * b32)) & ab13 = (((a11 * b13) + (a12 * b23)) + (a13 * b33)) & ab21 = (((a21 * b11) + (a22 * b21)) + (a23 * b31)) & ab22 = (((a21 * b12) + (a22 * b22)) + (a23 * b32)) & ab23 = (((a21 * b13) + (a22 * b23)) + (a23 * b33)) & ab31 = (((a31 * b11) + (a32 * b21)) + (a33 * b31)) & ab32 = (((a31 * b12) + (a32 * b22)) + (a33 * b32)) & ab33 = (((a31 * b13) + (a32 * b23)) + (a33 * b33)) holds (A * B) = <* <*ab11, ab12, ab13*>, <*ab21, ab22, ab23*>, <*ab31, ab32, ab33*>*> by ANPROJ_9: 6;

    theorem :: BKMODEL4:20

    

     Th11: for N1,N2 be Matrix of 3, F_Real st N1 = <* <*2, 0 , ( - 1)*>, <* 0 , ( sqrt 3), 0 *>, <*1, 0 , ( - 2)*>*> & N2 = <* <*(2 / 3), 0 , ( - (1 / 3))*>, <* 0 , (1 / ( sqrt 3)), 0 *>, <*(1 / 3), 0 , ( - (2 / 3))*>*> holds (N1 * N2) = <* <*1, 0 , 0 *>, <* 0 , 1, 0 *>, <* 0 , 0 , 1*>*>

    proof

      let N1,N2 be Matrix of 3, F_Real ;

      assume that

       A1: N1 = <* <*2, 0 , ( - 1)*>, <* 0 , ( sqrt 3), 0 *>, <*1, 0 , ( - 2)*>*> and

       A2: N2 = <* <*(2 / 3), 0 , ( - (1 / 3))*>, <* 0 , (1 / ( sqrt 3)), 0 *>, <*(1 / 3), 0 , ( - (2 / 3))*>*>;

      reconsider a = 2, b = 0 , c = ( - 1), d = 0 , e = ( sqrt 3), f = 0 , g = 1, h = 0 , i = ( - 2), a9 = (2 / 3), b9 = 0 , c9 = ( - (1 / 3)), d9 = 0 , e9 = (1 / ( sqrt 3)), f9 = 0 , g9 = (1 / 3), h9 = 0 , i9 = ( - (2 / 3)) as Element of F_Real by XREAL_0:def 1;

      reconsider n11 = (((a * a9) + (b * d9)) + (c * g9)), n12 = (((a * b9) + (b * e9)) + (c * h9)), n13 = (((a * c9) + (b * f9)) + (c * i9)), n21 = (((d * a9) + (e * d9)) + (f * g9)), n22 = (((d * b9) + (e * e9)) + (f * h9)), n23 = (((d * c9) + (e * f9)) + (f * i9)), n31 = (((g * a9) + (h * d9)) + (i * g9)), n32 = (((g * b9) + (h * e9)) + (i * h9)), n33 = (((g * c9) + (h * f9)) + (i * i9)) as Element of F_Real ;

      n11 = 1 & n12 = 0 & n13 = 0 & n21 = 0 & n22 = 1 & n23 = 0 & n31 = 0 & n32 = 0 & n33 = 1 by SQUARE_1: 24, XCMPLX_1: 106;

      hence thesis by A1, A2, Th10;

    end;

    theorem :: BKMODEL4:21

    

     Th12: for N1,N2 be Matrix of 3, F_Real st N2 = <* <*2, 0 , ( - 1)*>, <* 0 , ( sqrt 3), 0 *>, <*1, 0 , ( - 2)*>*> & N1 = <* <*(2 / 3), 0 , ( - (1 / 3))*>, <* 0 , (1 / ( sqrt 3)), 0 *>, <*(1 / 3), 0 , ( - (2 / 3))*>*> holds (N1 * N2) = <* <*1, 0 , 0 *>, <* 0 , 1, 0 *>, <* 0 , 0 , 1*>*>

    proof

      let N1,N2 be Matrix of 3, F_Real ;

      assume that

       A1: N2 = <* <*2, 0 , ( - 1)*>, <* 0 , ( sqrt 3), 0 *>, <*1, 0 , ( - 2)*>*> and

       A2: N1 = <* <*(2 / 3), 0 , ( - (1 / 3))*>, <* 0 , (1 / ( sqrt 3)), 0 *>, <*(1 / 3), 0 , ( - (2 / 3))*>*>;

      reconsider a9 = 2, b9 = 0 , c9 = ( - 1), d9 = 0 , e9 = ( sqrt 3), f9 = 0 , g9 = 1, h9 = 0 , i9 = ( - 2), a = (2 / 3), b = 0 , c = ( - (1 / 3)), d = 0 , e = (1 / ( sqrt 3)), f = 0 , g = (1 / 3), h = 0 , i = ( - (2 / 3)) as Element of F_Real by XREAL_0:def 1;

      reconsider n11 = (((a * a9) + (b * d9)) + (c * g9)), n12 = (((a * b9) + (b * e9)) + (c * h9)), n13 = (((a * c9) + (b * f9)) + (c * i9)), n21 = (((d * a9) + (e * d9)) + (f * g9)), n22 = (((d * b9) + (e * e9)) + (f * h9)), n23 = (((d * c9) + (e * f9)) + (f * i9)), n31 = (((g * a9) + (h * d9)) + (i * g9)), n32 = (((g * b9) + (h * e9)) + (i * h9)), n33 = (((g * c9) + (h * f9)) + (i * i9)) as Element of F_Real ;

      n11 = 1 & n12 = 0 & n13 = 0 & n21 = 0 & n22 = 1 & n23 = 0 & n31 = 0 & n32 = 0 & n33 = 1 by SQUARE_1: 24, XCMPLX_1: 106;

      hence thesis by A1, A2, Th10;

    end;

    theorem :: BKMODEL4:22

    

     Th13: for N1,N2 be Matrix of 3, F_Real st N1 = <* <*2, 0 , ( - 1)*>, <* 0 , ( sqrt 3), 0 *>, <*1, 0 , ( - 2)*>*> & N2 = <* <*(2 / 3), 0 , ( - (1 / 3))*>, <* 0 , (1 / ( sqrt 3)), 0 *>, <*(1 / 3), 0 , ( - (2 / 3))*>*> holds N1 is_reverse_of N2

    proof

      let N1,N2 be Matrix of 3, F_Real ;

      assume

       A1: N1 = <* <*2, 0 , ( - 1)*>, <* 0 , ( sqrt 3), 0 *>, <*1, 0 , ( - 2)*>*> & N2 = <* <*(2 / 3), 0 , ( - (1 / 3))*>, <* 0 , (1 / ( sqrt 3)), 0 *>, <*(1 / 3), 0 , ( - (2 / 3))*>*>;

      (N2 * N1) = ( 1. ( F_Real ,3)) & (N1 * N2) = ( 1. ( F_Real ,3)) by A1, Th11, Th12, ANPROJ_9: 1;

      hence thesis by MATRIX_6:def 2;

    end;

    theorem :: BKMODEL4:23

    

     Th14: for N be invertible Matrix of 3, F_Real st N = <* <*(2 / 3), 0 , ( - (1 / 3))*>, <* 0 , (1 / ( sqrt 3)), 0 *>, <*(1 / 3), 0 , ( - (2 / 3))*>*> holds (( homography N) .: absolute ) c= absolute

    proof

      let N be invertible Matrix of 3, F_Real ;

      assume

       A1: N = <* <*(2 / 3), 0 , ( - (1 / 3))*>, <* 0 , (1 / ( sqrt 3)), 0 *>, <*(1 / 3), 0 , ( - (2 / 3))*>*>;

      reconsider a = (2 / 3), b = 0 , c = ( - (1 / 3)), d = 0 , e = (1 / ( sqrt 3)), f = 0 , g = (1 / 3), h = 0 , i = ( - (2 / 3)) as Element of F_Real by XREAL_0:def 1;

      (( homography N) .: absolute ) c= absolute

      proof

        let x be object;

        assume x in (( homography N) .: absolute );

        then

        consider y be object such that

         A2: y in ( dom ( homography N)) and

         A3: y in absolute and

         A4: x = (( homography N) . y) by FUNCT_1:def 6;

        reconsider y as Point of ( ProjectiveSpace ( TOP-REAL 3)) by A2;

        consider yu be non zero Element of ( TOP-REAL 3) such that

         A5: (((yu . 1) ^2 ) + ((yu . 2) ^2 )) = 1 and

         A6: (yu . 3) = 1 and

         A7: y = ( Dir yu) by A3, BKMODEL1: 89;

        

         A8: (((yu `1 ) * (yu `1 )) + ((yu `2 ) * (yu `2 ))) = (((yu . 1) * (yu `1 )) + ((yu `2 ) * (yu `2 ))) by EUCLID_5:def 1

        .= (((yu . 1) * (yu . 1)) + ((yu `2 ) * (yu `2 ))) by EUCLID_5:def 1

        .= (((yu . 1) * (yu . 1)) + ((yu . 2) * (yu `2 ))) by EUCLID_5:def 2

        .= (((yu . 1) * (yu . 1)) + ((yu . 2) * (yu . 2))) by EUCLID_5:def 2

        .= (((yu . 1) ^2 ) + ((yu . 2) * (yu . 2))) by SQUARE_1:def 1

        .= 1 by A5, SQUARE_1:def 1;

        

         A9: ((yu `3 ) * (yu `3 )) = ((yu . 3) * (yu `3 )) by EUCLID_5:def 3

        .= 1 by A6, EUCLID_5:def 3;

        consider u,v be Element of ( TOP-REAL 3), uf be FinSequence of F_Real , p be FinSequence of (1 -tuples_on REAL ) such that

         A10: y = ( Dir u) & not u is zero & u = uf & p = (N * uf) & v = ( M2F p) & not v is zero & (( homography N) . y) = ( Dir v) by ANPROJ_8:def 4;

         are_Prop (u,yu) by A7, A10, ANPROJ_1: 22;

        then

        consider l be Real such that l <> 0 and

         A11: u = (l * yu) by ANPROJ_1: 1;

        reconsider u1 = (l * (yu `1 )), u2 = (l * (yu `2 )), u3 = (l * (yu `3 )) as Element of F_Real by XREAL_0:def 1;

        uf = <*u1, u2, u3*> by A11, A10, EUCLID_5: 7;

        

        then v = <*(((a * u1) + (b * u2)) + (c * u3)), (((d * u1) + (e * u2)) + (f * u3)), (((g * u1) + (h * u2)) + (i * u3))*> by A1, A10, PASCAL: 8

        .= <*(((2 / 3) * u1) - ((1 / 3) * u3)), ((1 / ( sqrt 3)) * u2), (((1 / 3) * u1) - ((2 / 3) * u3))*>;

        then (v `1 ) = (((2 / 3) * u1) - ((1 / 3) * u3)) & (v `2 ) = ((1 / ( sqrt 3)) * u2) & (v `3 ) = (((1 / 3) * u1) - ((2 / 3) * u3)) by EUCLID_5: 2;

        then

         A12: (v . 1) = (((2 / 3) * u1) - ((1 / 3) * u3)) & (v . 2) = ((1 / ( sqrt 3)) * u2) & (v . 3) = (((1 / 3) * u1) - ((2 / 3) * u3)) by EUCLID_5:def 1, EUCLID_5:def 2, EUCLID_5:def 3;

        set k = ((1 / 3) * (1 / 3));

        (1 / ( sqrt 3)) = (( sqrt 3) / 3) by BKMODEL3: 10;

        

        then

         A13: ((1 / ( sqrt 3)) * (1 / ( sqrt 3))) = (k * (( sqrt 3) * ( sqrt 3)))

        .= (k * ( sqrt (3 * 3))) by SQUARE_1: 29

        .= (k * ( sqrt (3 ^2 ))) by SQUARE_1:def 1

        .= (k * 3) by SQUARE_1:def 2;

        

         A14: ((v . 2) * (v . 2)) = ((((1 / ( sqrt 3)) * (1 / ( sqrt 3))) * u2) * u2) by A12

        .= (((k * 3) * u2) * u2) by A13;

        reconsider P = (( homography N) . y) as Point of ( ProjectiveSpace ( TOP-REAL 3));

        ( qfconic (1,1,( - 1), 0 , 0 , 0 ,v)) = 0

        proof

          ( qfconic (1,1,( - 1), 0 , 0 , 0 ,v)) = (((((((1 * (v . 1)) * (v . 1)) + ((1 * (v . 2)) * (v . 2))) + ((( - 1) * (v . 3)) * (v . 3))) + (( 0 * (v . 1)) * (v . 2))) + (( 0 * (v . 1)) * (v . 3))) + (( 0 * (v . 2)) * (v . 3))) by PASCAL:def 1

          .= (((k * ((((4 * u1) * u1) - ((4 * u1) * u3)) + (u3 * u3))) + (((k * 3) * u2) * u2)) - (k * (((u1 * u1) - ((4 * u1) * u3)) + ((4 * u3) * u3)))) by A12, A14

          .= (((k * 3) * (l * l)) * ((((yu `1 ) * (yu `1 )) + ((yu `2 ) * (yu `2 ))) - ((yu `3 ) * (yu `3 ))))

          .= 0 by A8, A9;

          hence thesis;

        end;

        hence x in absolute by A4, A10, PASCAL: 11;

      end;

      hence thesis;

    end;

    theorem :: BKMODEL4:24

    for N be invertible Matrix of 3, F_Real st N = <* <*2, 0 , ( - 1)*>, <* 0 , ( sqrt 3), 0 *>, <*1, 0 , ( - 2)*>*> holds (( homography N) .: absolute ) = absolute

    proof

      let N be invertible Matrix of 3, F_Real ;

      assume

       A1: N = <* <*2, 0 , ( - 1)*>, <* 0 , ( sqrt 3), 0 *>, <*1, 0 , ( - 2)*>*>;

      reconsider a = 2, b = 0 , c = ( - 1), d = 0 , e = ( sqrt 3), f = 0 , g = 1, h = 0 , i = ( - 2) as Element of F_Real by XREAL_0:def 1;

      

       A2: (( homography N) .: absolute ) c= absolute

      proof

        let x be object;

        assume x in (( homography N) .: absolute );

        then

        consider y be object such that

         A3: y in ( dom ( homography N)) and

         A4: y in absolute and

         A5: x = (( homography N) . y) by FUNCT_1:def 6;

        reconsider y as Point of ( ProjectiveSpace ( TOP-REAL 3)) by A3;

        consider yu be non zero Element of ( TOP-REAL 3) such that

         A6: (((yu . 1) ^2 ) + ((yu . 2) ^2 )) = 1 and

         A7: (yu . 3) = 1 and

         A8: y = ( Dir yu) by A4, BKMODEL1: 89;

        

         A9: (((yu `1 ) * (yu `1 )) + ((yu `2 ) * (yu `2 ))) = (((yu . 1) * (yu `1 )) + ((yu `2 ) * (yu `2 ))) by EUCLID_5:def 1

        .= (((yu . 1) * (yu . 1)) + ((yu `2 ) * (yu `2 ))) by EUCLID_5:def 1

        .= (((yu . 1) * (yu . 1)) + ((yu . 2) * (yu `2 ))) by EUCLID_5:def 2

        .= (((yu . 1) * (yu . 1)) + ((yu . 2) * (yu . 2))) by EUCLID_5:def 2

        .= (((yu . 1) ^2 ) + ((yu . 2) * (yu . 2))) by SQUARE_1:def 1

        .= 1 by A6, SQUARE_1:def 1;

        

         A10: ((yu `3 ) * (yu `3 )) = ((yu . 3) * (yu `3 )) by EUCLID_5:def 3

        .= 1 by A7, EUCLID_5:def 3;

        consider u,v be Element of ( TOP-REAL 3), uf be FinSequence of F_Real , p be FinSequence of (1 -tuples_on REAL ) such that

         A11: y = ( Dir u) & not u is zero & u = uf & p = (N * uf) & v = ( M2F p) & not v is zero & (( homography N) . y) = ( Dir v) by ANPROJ_8:def 4;

         are_Prop (u,yu) by A8, A11, ANPROJ_1: 22;

        then

        consider l be Real such that l <> 0 and

         A12: u = (l * yu) by ANPROJ_1: 1;

        reconsider u1 = (l * (yu `1 )), u2 = (l * (yu `2 )), u3 = (l * (yu `3 )) as Element of F_Real by XREAL_0:def 1;

        uf = <*u1, u2, u3*> by A12, EUCLID_5: 7, A11;

        

        then v = <*(((a * u1) + (b * u2)) + (c * u3)), (((d * u1) + (e * u2)) + (f * u3)), (((g * u1) + (h * u2)) + (i * u3))*> by A1, A11, PASCAL: 8

        .= <*((2 * u1) - u3), (( sqrt 3) * u2), (u1 - (2 * u3))*>;

        then (v `1 ) = ((2 * u1) - u3) & (v `2 ) = (( sqrt 3) * u2) & (v `3 ) = (u1 - (2 * u3)) by EUCLID_5: 2;

        then

         A13: (v . 1) = ((2 * u1) - u3) & (v . 2) = (( sqrt 3) * u2) & (v . 3) = (u1 - (2 * u3)) by EUCLID_5:def 1, EUCLID_5:def 2, EUCLID_5:def 3;

        

         A14: ((v . 1) * (v . 1)) = (((2 * u1) - u3) ^2 ) by A13, SQUARE_1:def 1

        .= ((((2 * u1) ^2 ) - ((2 * (2 * u1)) * u3)) + (u3 ^2 )) by SQUARE_1: 5

        .= ((((2 * u1) * (2 * u1)) - ((2 * (2 * u1)) * u3)) + (u3 ^2 )) by SQUARE_1:def 1

        .= ((((4 * u1) * u1) - ((4 * u1) * u3)) + (u3 * u3)) by SQUARE_1:def 1;

        

         A15: ((v . 2) * (v . 2)) = (((( sqrt 3) * ( sqrt 3)) * u2) * u2) by A13

        .= ((( sqrt (3 * 3)) * u2) * u2) by SQUARE_1: 29

        .= ((( sqrt (3 ^2 )) * u2) * u2) by SQUARE_1:def 1

        .= ((3 * u2) * u2) by SQUARE_1:def 2;

        

         A16: ((v . 3) * (v . 3)) = ((u1 - (2 * u3)) ^2 ) by A13, SQUARE_1:def 1

        .= (((u1 ^2 ) - ((2 * u1) * (2 * u3))) + ((2 * u3) ^2 )) by SQUARE_1: 5

        .= (((u1 * u1) - (((2 * 2) * u1) * u3)) + ((2 * u3) ^2 )) by SQUARE_1:def 1

        .= (((u1 * u1) - (((2 * 2) * u1) * u3)) + ((2 * u3) * (2 * u3))) by SQUARE_1:def 1

        .= (((u1 * u1) - ((4 * u1) * u3)) + ((4 * u3) * u3));

        reconsider P = (( homography N) . y) as Point of ( ProjectiveSpace ( TOP-REAL 3));

        ( qfconic (1,1,( - 1), 0 , 0 , 0 ,v)) = 0

        proof

          ( qfconic (1,1,( - 1), 0 , 0 , 0 ,v)) = (((((((1 * (v . 1)) * (v . 1)) + ((1 * (v . 2)) * (v . 2))) + ((( - 1) * (v . 3)) * (v . 3))) + (( 0 * (v . 1)) * (v . 2))) + (( 0 * (v . 1)) * (v . 3))) + (( 0 * (v . 2)) * (v . 3))) by PASCAL:def 1

          .= ((((((4 * u1) * u1) - ((4 * u1) * u3)) + (u3 * u3)) + ((3 * u2) * u2)) - (((u1 * u1) - ((4 * u1) * u3)) + ((4 * u3) * u3))) by A14, A15, A16

          .= ((3 * (l * l)) * ((((yu `1 ) * (yu `1 )) + ((yu `2 ) * (yu `2 ))) - ((yu `3 ) * (yu `3 ))))

          .= 0 by A9, A10;

          hence thesis;

        end;

        hence x in absolute by A5, A11, PASCAL: 11;

      end;

       absolute c= (( homography N) .: absolute )

      proof

        let x be object;

        assume

         A17: x in absolute ;

        reconsider N1 = <* <*(2 / 3), 0 , ( - (1 / 3))*>, <* 0 , (1 / ( sqrt 3)), 0 *>, <*(1 / 3), 0 , ( - (2 / 3))*>*> as Matrix of 3, F_Real by ANPROJ_8: 19;

        N1 is_reverse_of N by A1, Th13;

        then

        reconsider N1 as invertible Matrix of 3, F_Real by MATRIX_6:def 3;

        

         A18: (( homography N1) .: absolute ) c= absolute by Th14;

        ( dom ( homography N1)) = the carrier of ( ProjectiveSpace ( TOP-REAL 3)) by FUNCT_2:def 1;

        then (( homography N1) . x) in (( homography N1) .: absolute ) by A17, FUNCT_1: 108;

        then

        reconsider y = (( homography N1) . x) as Element of absolute by A18;

        

         A19: (N * N1) = ( 1. ( F_Real ,3)) by A1, Th11, ANPROJ_9: 1;

        now

          ( dom ( homography N)) = the carrier of ( ProjectiveSpace ( TOP-REAL 3)) by FUNCT_2:def 1;

          hence y in ( dom ( homography N));

          thus y in absolute ;

          reconsider P = x as Point of ( ProjectiveSpace ( TOP-REAL 3)) by A17;

          

          thus (( homography N) . y) = (( homography ( 1. ( F_Real ,3))) . P) by A19, ANPROJ_9: 13

          .= x by ANPROJ_9: 14;

        end;

        hence x in (( homography N) .: absolute ) by FUNCT_1: 108;

      end;

      hence thesis by A2;

    end;

    theorem :: BKMODEL4:25

    

     Th15: for a,b,r be Real holds for P,Q,R be Element of ( TOP-REAL 2) st Q in ( LSeg (P,R)) & P in ( inside_of_circle (a,b,r)) & R in ( inside_of_circle (a,b,r)) holds Q in ( inside_of_circle (a,b,r))

    proof

      let a,b,r be Real;

      let P,Q,R be Element of ( TOP-REAL 2);

      assume that

       A1: Q in ( LSeg (P,R)) and

       A2: P in ( inside_of_circle (a,b,r)) and

       A3: R in ( inside_of_circle (a,b,r));

      consider s be Real such that

       A4: 0 <= s & s <= 1 and

       A5: Q = (((1 - s) * P) + (s * R)) by A1, RLTOPSP1: 76;

      s in [. 0 , 1.] by A4, XXREAL_1: 1;

      then s in ]. 0 , 1.[ or s = 0 or s = 1 by XXREAL_1: 5;

      per cases by XXREAL_1: 4;

        suppose

         A6: 0 < s & s < 1;

        Q = ((s * R) + ((1 - s) * P)) by A5;

        hence thesis by A2, A3, A6, CONVEX1:def 2;

      end;

        suppose s = 0 ;

        

        then Q = (P + ( 0 * R)) by A5, RVSUM_1: 52

        .= P by GTARSKI2: 2;

        hence thesis by A2;

      end;

        suppose s = 1;

        

        then Q = (R + ( 0 * P)) by A5, RVSUM_1: 52

        .= R by GTARSKI2: 2;

        hence thesis by A3;

      end;

    end;

    theorem :: BKMODEL4:26

    

     Th16: for u,v be non zero Element of ( TOP-REAL 3) st ( Dir u) = ( Dir v) & (u . 3) <> 0 & (u . 3) = (v . 3) holds u = v

    proof

      let u,v be non zero Element of ( TOP-REAL 3);

      assume that

       A1: ( Dir u) = ( Dir v) and

       A2: (u . 3) <> 0 and

       A3: (u . 3) = (v . 3);

       are_Prop (u,v) by A1, ANPROJ_1: 22;

      then

      consider a be Real such that a <> 0 and

       A4: u = (a * v) by ANPROJ_1: 1;

      (u . 3) = (a * (u . 3)) by A3, A4, RVSUM_1: 44;

      then a = 1 by A2, XCMPLX_1: 7;

      hence thesis by A4, RVSUM_1: 52;

    end;

    theorem :: BKMODEL4:27

    

     Th17: for R be Element of ( ProjectiveSpace ( TOP-REAL 3)) holds for P,Q be Element of BK_model holds for u,v,w be non zero Element of ( TOP-REAL 3) holds for r be Real st 0 <= r <= 1 & P = ( Dir u) & Q = ( Dir v) & R = ( Dir w) & (u . 3) = 1 & (v . 3) = 1 & w = ((r * u) + ((1 - r) * v)) holds R is Element of BK_model

    proof

      let R be Element of ( ProjectiveSpace ( TOP-REAL 3));

      let P,Q be Element of BK_model ;

      let u,v,w be non zero Element of ( TOP-REAL 3);

      let r be Real;

      assume that

       A1: 0 <= r <= 1 and

       A2: P = ( Dir u) & Q = ( Dir v) & R = ( Dir w) and

       A3: (u . 3) = 1 & (v . 3) = 1 and

       A4: w = ((r * u) + ((1 - r) * v));

      reconsider ru = (r * u), rv = ((1 - r) * v) as Element of ( REAL 3) by EUCLID: 22;

      

       A5: (w . 3) = ((ru . 3) + (rv . 3)) by A4, RVSUM_1: 11

      .= ((r * (u . 3)) + (rv . 3)) by RVSUM_1: 44

      .= (r + ((1 - r) * 1)) by A3, RVSUM_1: 44

      .= 1;

      consider u2 be non zero Element of ( TOP-REAL 3) such that

       A6: ( Dir u2) = P & (u2 . 3) = 1 & ( BK_to_REAL2 P) = |[(u2 . 1), (u2 . 2)]| by BKMODEL2:def 2;

      

       A7: u = u2 by A2, A3, A6, Th16;

      reconsider ru2 = |[(u2 . 1), (u2 . 2)]| as Element of ( TOP-REAL 2);

      consider v2 be non zero Element of ( TOP-REAL 3) such that

       A8: ( Dir v2) = Q & (v2 . 3) = 1 & ( BK_to_REAL2 Q) = |[(v2 . 1), (v2 . 2)]| by BKMODEL2:def 2;

      

       A9: v = v2 by A2, A3, A8, Th16;

      reconsider rv2 = |[(v2 . 1), (v2 . 2)]| as Element of ( TOP-REAL 2);

      reconsider rw = |[(w . 1), (w . 2)]| as Element of ( TOP-REAL 2);

      rw = ((r * ru2) + ((1 - r) * rv2))

      proof

        

         A10: (w . 1) = ((ru . 1) + (rv . 1)) by A4, RVSUM_1: 11

        .= ((r * (u . 1)) + (rv . 1)) by RVSUM_1: 44

        .= ((r * (u2 . 1)) + ((1 - r) * (v2 . 1))) by A7, A9, RVSUM_1: 44;

        

         A13: (w . 2) = ((ru . 2) + (rv . 2)) by A4, RVSUM_1: 11

        .= ((r * (u . 2)) + (rv . 2)) by RVSUM_1: 44

        .= ((r * (u2 . 2)) + ((1 - r) * (v2 . 2))) by A7, A9, RVSUM_1: 44;

        ((r * ru2) + ((1 - r) * rv2)) = ( |[(r * (u2 . 1)), (r * (u2 . 2))]| + ((1 - r) * |[(v2 . 1), (v2 . 2)]|)) by EUCLID: 58

        .= ( |[(r * (u2 . 1)), (r * (u2 . 2))]| + |[((1 - r) * (v2 . 1)), ((1 - r) * (v2 . 2))]|) by EUCLID: 58;

        hence thesis by A10, A13, EUCLID: 56;

      end;

      then rw = (((1 - r) * rv2) + (r * ru2));

      then rw in { (((1 - r) * rv2) + (r * ru2)) where r be Real : 0 <= r & r <= 1 } by A1;

      then rw in ( LSeg (rv2,ru2)) by RLTOPSP1:def 2;

      then

      reconsider rw as Element of ( inside_of_circle ( 0 , 0 ,1)) by A6, A8, Th15;

      consider RW2 be Element of ( TOP-REAL 2) such that

       A11: RW2 = rw & ( REAL2_to_BK rw) = ( Dir |[(RW2 `1 ), (RW2 `2 ), 1]|) by BKMODEL2:def 3;

      

       A12: (rw `1 ) = (w . 1) & (rw `2 ) = (w . 2) by EUCLID: 52;

      w = |[(w `1 ), (w `2 ), (w `3 )]| by EUCLID_5: 3

      .= |[(w . 1), (w `2 ), (w `3 )]| by EUCLID_5:def 1

      .= |[(w . 1), (w . 2), (w `3 )]| by EUCLID_5:def 2

      .= |[(w . 1), (w . 2), (w . 3)]| by EUCLID_5:def 3;

      hence thesis by A2, A11, A5, A12;

    end;

    theorem :: BKMODEL4:28

    

     Th18: for N be invertible Matrix of 3, F_Real holds for n11,n12,n13,n21,n22,n23,n31,n32,n33 be Element of F_Real holds for P,Q be Point of ( ProjectiveSpace ( TOP-REAL 3)) holds for u,v be non zero Element of ( TOP-REAL 3) st N = <* <*n11, n12, n13*>, <*n21, n22, n23*>, <*n31, n32, n33*>*> & P = ( Dir u) & Q = ( Dir v) & Q = (( homography N) . P) & (u . 3) = 1 holds ex a be non zero Real st (v . 1) = (a * (((n11 * (u . 1)) + (n12 * (u . 2))) + n13)) & (v . 2) = (a * (((n21 * (u . 1)) + (n22 * (u . 2))) + n23)) & (v . 3) = (a * (((n31 * (u . 1)) + (n32 * (u . 2))) + n33))

    proof

      let N be invertible Matrix of 3, F_Real ;

      let n11,n12,n13,n21,n22,n23,n31,n32,n33 be Element of F_Real ;

      let P,Q be Point of ( ProjectiveSpace ( TOP-REAL 3));

      let u,v be non zero Element of ( TOP-REAL 3);

      assume

       A1: N = <* <*n11, n12, n13*>, <*n21, n22, n23*>, <*n31, n32, n33*>*> & P = ( Dir u) & Q = ( Dir v) & Q = (( homography N) . P) & (u . 3) = 1;

      consider u9,v9 be Element of ( TOP-REAL 3), uf be FinSequence of F_Real , p be FinSequence of (1 -tuples_on REAL ) such that

       A2: P = ( Dir u9) & not u9 is zero & u9 = uf & p = (N * uf) & v9 = ( M2F p) & not v9 is zero & (( homography N) . P) = ( Dir v9) by ANPROJ_8:def 4;

       are_Prop (u,u9) by A1, A2, ANPROJ_1: 22;

      then

      consider a be Real such that

       A3: a <> 0 & u9 = (a * u) by ANPROJ_1: 1;

      

       A4: |[(u9 `1 ), (u9 `2 ), (u9 `3 )]| = u9 by EUCLID_5: 3

      .= |[(a * (u `1 )), (a * (u `2 )), (a * (u `3 ))]| by A3, EUCLID_5: 7

      .= |[(a * (u `1 )), (a * (u `2 )), (a * (u . 3))]| by EUCLID_5:def 3

      .= |[(a * (u `1 )), (a * (u `2 )), a]| by A1;

      reconsider uf1 = (a * (u `1 )), uf2 = (a * (u `2 )), uf3 = a as Element of F_Real by XREAL_0:def 1;

      reconsider x1 = (((n11 * (u `1 )) + (n12 * (u `2 ))) + n13), x2 = (((n21 * (u `1 )) + (n22 * (u `2 ))) + n23), x3 = (((n31 * (u `1 )) + (n32 * (u `2 ))) + n33) as Element of REAL by XREAL_0:def 1;

      uf = <*uf1, uf2, uf3*> by A2, A4, EUCLID_5: 3;

      

      then

       A5: v9 = <*(((n11 * uf1) + (n12 * uf2)) + (n13 * uf3)), (((n21 * uf1) + (n22 * uf2)) + (n23 * uf3)), (((n31 * uf1) + (n32 * uf2)) + (n33 * uf3))*> by A1, A2, PASCAL: 8

      .= <*(a * (((n11 * (u `1 )) + (n12 * (u `2 ))) + n13)), (a * (((n21 * (u `1 )) + (n22 * (u `2 ))) + n23)), (a * (((n31 * (u `1 )) + (n32 * (u `2 ))) + n33))*>

      .= (a * |[x1, x2, x3]|) by EUCLID_5: 8;

       are_Prop (v,v9) by A1, A2, ANPROJ_1: 22;

      then

      consider b be Real such that

       A6: b <> 0 and

       A7: v = (b * v9) by ANPROJ_1: 1;

      

       A8: v = (b * |[(a * x1), (a * x2), (a * x3)]|) by A7, A5, EUCLID_5: 8

      .= |[(b * (a * x1)), (b * (a * x2)), (b * (a * x3))]| by EUCLID_5: 8

      .= |[((b * a) * (((n11 * (u `1 )) + (n12 * (u `2 ))) + n13)), ((b * a) * (((n21 * (u `1 )) + (n22 * (u `2 ))) + n23)), ((b * a) * (((n31 * (u `1 )) + (n32 * (u `2 ))) + n33))]|;

      reconsider c = (b * a) as non zero Real by A3, A6;

      take c;

      (v `1 ) = (c * (((n11 * (u `1 )) + (n12 * (u `2 ))) + n13)) & (v `2 ) = (c * (((n21 * (u `1 )) + (n22 * (u `2 ))) + n23)) & (v `3 ) = (c * (((n31 * (u `1 )) + (n32 * (u `2 ))) + n33)) by A8, EUCLID_5: 2;

      then (v . 1) = (c * (((n11 * (u `1 )) + (n12 * (u `2 ))) + n13)) & (v . 2) = (c * (((n21 * (u `1 )) + (n22 * (u `2 ))) + n23)) & (v . 3) = (c * (((n31 * (u `1 )) + (n32 * (u `2 ))) + n33)) by EUCLID_5:def 1, EUCLID_5:def 2, EUCLID_5:def 3;

      then (v . 1) = (c * (((n11 * (u . 1)) + (n12 * (u `2 ))) + n13)) & (v . 2) = (c * (((n21 * (u . 1)) + (n22 * (u `2 ))) + n23)) & (v . 3) = (c * (((n31 * (u . 1)) + (n32 * (u `2 ))) + n33)) by EUCLID_5:def 1;

      hence thesis by EUCLID_5:def 2;

    end;

    theorem :: BKMODEL4:29

    

     Th19: for N be invertible Matrix of 3, F_Real holds for n11,n12,n13,n21,n22,n23,n31,n32,n33 be Element of F_Real holds for P be Element of BK_model holds for Q be Point of ( ProjectiveSpace ( TOP-REAL 3)) holds for u,v be non zero Element of ( TOP-REAL 3) st N = <* <*n11, n12, n13*>, <*n21, n22, n23*>, <*n31, n32, n33*>*> & P = ( Dir u) & Q = ( Dir v) & Q = (( homography N) . P) & (u . 3) = 1 & (v . 3) = 1 holds (((n31 * (u . 1)) + (n32 * (u . 2))) + n33) <> 0 & (v . 1) = ((((n11 * (u . 1)) + (n12 * (u . 2))) + n13) / (((n31 * (u . 1)) + (n32 * (u . 2))) + n33)) & (v . 2) = ((((n21 * (u . 1)) + (n22 * (u . 2))) + n23) / (((n31 * (u . 1)) + (n32 * (u . 2))) + n33))

    proof

      let N be invertible Matrix of 3, F_Real ;

      let n11,n12,n13,n21,n22,n23,n31,n32,n33 be Element of F_Real ;

      let P be Element of BK_model ;

      let Q be Point of ( ProjectiveSpace ( TOP-REAL 3));

      let u,v be non zero Element of ( TOP-REAL 3);

      assume that

       A1: N = <* <*n11, n12, n13*>, <*n21, n22, n23*>, <*n31, n32, n33*>*> and

       A2: P = ( Dir u) and

       A3: Q = ( Dir v) and

       A4: Q = (( homography N) . P) and

       A5: (u . 3) = 1 and

       A6: (v . 3) = 1;

      consider a be non zero Real such that

       A7: (v . 1) = (a * (((n11 * (u . 1)) + (n12 * (u . 2))) + n13)) and

       A8: (v . 2) = (a * (((n21 * (u . 1)) + (n22 * (u . 2))) + n23)) and

       A9: (v . 3) = (a * (((n31 * (u . 1)) + (n32 * (u . 2))) + n33)) by A1, A2, A3, A4, A5, Th18;

      thus (((n31 * (u . 1)) + (n32 * (u . 2))) + n33) <> 0 by A6, A9;

      reconsider nn = (((n31 * (u . 1)) + (n32 * (u . 2))) + n33) as non zero Real by A6, A9;

      a = (1 / nn) by A6, A9, XCMPLX_1: 73;

      hence thesis by A7, A8;

    end;

    theorem :: BKMODEL4:30

    

     Th20: for N be invertible Matrix of 3, F_Real holds for h be Element of SubGroupK-isometry holds for n11,n12,n13,n21,n22,n23,n31,n32,n33 be Element of F_Real holds for P be Element of BK_model holds for u be non zero Element of ( TOP-REAL 3) st h = ( homography N) & N = <* <*n11, n12, n13*>, <*n21, n22, n23*>, <*n31, n32, n33*>*> & P = ( Dir u) & (u . 3) = 1 holds (((n31 * (u . 1)) + (n32 * (u . 2))) + n33) <> 0

    proof

      let N be invertible Matrix of 3, F_Real ;

      let h be Element of SubGroupK-isometry ;

      let n11,n12,n13,n21,n22,n23,n31,n32,n33 be Element of F_Real ;

      let P be Element of BK_model ;

      let u be non zero Element of ( TOP-REAL 3);

      assume

       A1: h = ( homography N) & N = <* <*n11, n12, n13*>, <*n21, n22, n23*>, <*n31, n32, n33*>*> & P = ( Dir u) & (u . 3) = 1;

      reconsider Q = (( homography N) . P) as Point of ( ProjectiveSpace ( TOP-REAL 3));

      reconsider Q = (( homography N) . P) as Element of BK_model by A1, BKMODEL3: 36;

      ex v be non zero Element of ( TOP-REAL 3) st Q = ( Dir v) & (v . 3) = 1 & ( BK_to_REAL2 Q) = |[(v . 1), (v . 2)]| by BKMODEL2:def 2;

      hence thesis by A1, Th19;

    end;

    theorem :: BKMODEL4:31

    

     Th21: for N be invertible Matrix of 3, F_Real holds for n11,n12,n13,n21,n22,n23,n31,n32,n33 be Element of F_Real holds for P be Element of absolute holds for Q be Point of ( ProjectiveSpace ( TOP-REAL 3)) holds for u,v be non zero Element of ( TOP-REAL 3) st N = <* <*n11, n12, n13*>, <*n21, n22, n23*>, <*n31, n32, n33*>*> & P = ( Dir u) & Q = ( Dir v) & Q = (( homography N) . P) & (u . 3) = 1 & (v . 3) = 1 holds (((n31 * (u . 1)) + (n32 * (u . 2))) + n33) <> 0 & (v . 1) = ((((n11 * (u . 1)) + (n12 * (u . 2))) + n13) / (((n31 * (u . 1)) + (n32 * (u . 2))) + n33)) & (v . 2) = ((((n21 * (u . 1)) + (n22 * (u . 2))) + n23) / (((n31 * (u . 1)) + (n32 * (u . 2))) + n33))

    proof

      let N be invertible Matrix of 3, F_Real ;

      let n11,n12,n13,n21,n22,n23,n31,n32,n33 be Element of F_Real ;

      let P be Element of absolute ;

      let Q be Point of ( ProjectiveSpace ( TOP-REAL 3));

      let u,v be non zero Element of ( TOP-REAL 3);

      assume

       A1: N = <* <*n11, n12, n13*>, <*n21, n22, n23*>, <*n31, n32, n33*>*> & P = ( Dir u) & Q = ( Dir v) & Q = (( homography N) . P) & (u . 3) = 1 & (v . 3) = 1;

      consider a be non zero Real such that

       A2: (v . 1) = (a * (((n11 * (u . 1)) + (n12 * (u . 2))) + n13)) and

       A3: (v . 2) = (a * (((n21 * (u . 1)) + (n22 * (u . 2))) + n23)) and

       A4: (v . 3) = (a * (((n31 * (u . 1)) + (n32 * (u . 2))) + n33)) by A1, Th18;

      thus (((n31 * (u . 1)) + (n32 * (u . 2))) + n33) <> 0 by A1, A4;

      reconsider nn = (((n31 * (u . 1)) + (n32 * (u . 2))) + n33) as non zero Real by A1, A4;

      a = (1 / nn) by A1, A4, XCMPLX_1: 73;

      hence thesis by A2, A3;

    end;

    theorem :: BKMODEL4:32

    

     Th22: for N be invertible Matrix of 3, F_Real holds for h be Element of SubGroupK-isometry holds for n11,n12,n13,n21,n22,n23,n31,n32,n33 be Element of F_Real holds for P be Element of absolute holds for u be non zero Element of ( TOP-REAL 3) st h = ( homography N) & N = <* <*n11, n12, n13*>, <*n21, n22, n23*>, <*n31, n32, n33*>*> & P = ( Dir u) & (u . 3) = 1 holds (((n31 * (u . 1)) + (n32 * (u . 2))) + n33) <> 0

    proof

      let N be invertible Matrix of 3, F_Real ;

      let h be Element of SubGroupK-isometry ;

      let n11,n12,n13,n21,n22,n23,n31,n32,n33 be Element of F_Real ;

      let P be Element of absolute ;

      let u be non zero Element of ( TOP-REAL 3);

      assume

       A1: h = ( homography N) & N = <* <*n11, n12, n13*>, <*n21, n22, n23*>, <*n31, n32, n33*>*> & P = ( Dir u) & (u . 3) = 1;

      reconsider Q = (( homography N) . P) as Point of ( ProjectiveSpace ( TOP-REAL 3));

      reconsider Q = (( homography N) . P) as Element of absolute by A1, BKMODEL3: 35;

      ex v be non zero Element of ( TOP-REAL 3) st Q = ( Dir v) & (v . 3) = 1 & ( absolute_to_REAL2 Q) = |[(v . 1), (v . 2)]| by BKMODEL1:def 8;

      hence thesis by A1, Th21;

    end;

    theorem :: BKMODEL4:33

    

     Th23: for N be invertible Matrix of 3, F_Real holds for h be Element of SubGroupK-isometry holds for n11,n12,n13,n21,n22,n23,n31,n32,n33 be Element of F_Real holds for P be Element of BK_model holds for u be non zero Element of ( TOP-REAL 3) st h = ( homography N) & N = <* <*n11, n12, n13*>, <*n21, n22, n23*>, <*n31, n32, n33*>*> & P = ( Dir u) & (u . 3) = 1 holds (( homography N) . P) = ( Dir |[((((n11 * (u . 1)) + (n12 * (u . 2))) + n13) / (((n31 * (u . 1)) + (n32 * (u . 2))) + n33)), ((((n21 * (u . 1)) + (n22 * (u . 2))) + n23) / (((n31 * (u . 1)) + (n32 * (u . 2))) + n33)), 1]|)

    proof

      let N be invertible Matrix of 3, F_Real ;

      let h be Element of SubGroupK-isometry ;

      let n11,n12,n13,n21,n22,n23,n31,n32,n33 be Element of F_Real ;

      let P be Element of BK_model ;

      let u be non zero Element of ( TOP-REAL 3);

      assume

       A1: h = ( homography N) & N = <* <*n11, n12, n13*>, <*n21, n22, n23*>, <*n31, n32, n33*>*> & P = ( Dir u) & (u . 3) = 1;

      reconsider Q = (( homography N) . P) as Element of BK_model by A1, BKMODEL3: 36;

      consider v be non zero Element of ( TOP-REAL 3) such that

       A2: Q = ( Dir v) & (v . 3) = 1 & ( BK_to_REAL2 Q) = |[(v . 1), (v . 2)]| by BKMODEL2:def 2;

      (((n31 * (u . 1)) + (n32 * (u . 2))) + n33) <> 0 & (v . 1) = ((((n11 * (u . 1)) + (n12 * (u . 2))) + n13) / (((n31 * (u . 1)) + (n32 * (u . 2))) + n33)) & (v . 2) = ((((n21 * (u . 1)) + (n22 * (u . 2))) + n23) / (((n31 * (u . 1)) + (n32 * (u . 2))) + n33)) by A2, A1, Th19;

      then (v `1 ) = ((((n11 * (u . 1)) + (n12 * (u . 2))) + n13) / (((n31 * (u . 1)) + (n32 * (u . 2))) + n33)) & (v `2 ) = ((((n21 * (u . 1)) + (n22 * (u . 2))) + n23) / (((n31 * (u . 1)) + (n32 * (u . 2))) + n33)) & (v `3 ) = 1 by A2, EUCLID_5:def 1, EUCLID_5:def 2, EUCLID_5:def 3;

      hence thesis by A2, EUCLID_5: 3;

    end;

    theorem :: BKMODEL4:34

    

     Th24: for N be invertible Matrix of 3, F_Real holds for h be Element of SubGroupK-isometry holds for n11,n12,n13,n21,n22,n23,n31,n32,n33 be Element of F_Real holds for P be Element of absolute holds for u be non zero Element of ( TOP-REAL 3) st h = ( homography N) & N = <* <*n11, n12, n13*>, <*n21, n22, n23*>, <*n31, n32, n33*>*> & P = ( Dir u) & (u . 3) = 1 holds (( homography N) . P) = ( Dir |[((((n11 * (u . 1)) + (n12 * (u . 2))) + n13) / (((n31 * (u . 1)) + (n32 * (u . 2))) + n33)), ((((n21 * (u . 1)) + (n22 * (u . 2))) + n23) / (((n31 * (u . 1)) + (n32 * (u . 2))) + n33)), 1]|)

    proof

      let N be invertible Matrix of 3, F_Real ;

      let h be Element of SubGroupK-isometry ;

      let n11,n12,n13,n21,n22,n23,n31,n32,n33 be Element of F_Real ;

      let P be Element of absolute ;

      let u be non zero Element of ( TOP-REAL 3);

      assume that

       A1: h = ( homography N) & N = <* <*n11, n12, n13*>, <*n21, n22, n23*>, <*n31, n32, n33*>*> and

       A2: P = ( Dir u) & (u . 3) = 1;

      reconsider Q = (( homography N) . P) as Element of absolute by A1, BKMODEL3: 35;

      consider v be non zero Element of ( TOP-REAL 3) such that

       A3: Q = ( Dir v) & (v . 3) = 1 & ( absolute_to_REAL2 Q) = |[(v . 1), (v . 2)]| by BKMODEL1:def 8;

      now

        (((n31 * (u . 1)) + (n32 * (u . 2))) + n33) <> 0 & (v . 1) = ((((n11 * (u . 1)) + (n12 * (u . 2))) + n13) / (((n31 * (u . 1)) + (n32 * (u . 2))) + n33)) & (v . 2) = ((((n21 * (u . 1)) + (n22 * (u . 2))) + n23) / (((n31 * (u . 1)) + (n32 * (u . 2))) + n33)) by A3, A2, A1, Th21;

        hence (v `1 ) = ((((n11 * (u . 1)) + (n12 * (u . 2))) + n13) / (((n31 * (u . 1)) + (n32 * (u . 2))) + n33)) & (v `2 ) = ((((n21 * (u . 1)) + (n22 * (u . 2))) + n23) / (((n31 * (u . 1)) + (n32 * (u . 2))) + n33)) & (v `3 ) = 1 by A3, EUCLID_5:def 1, EUCLID_5:def 2, EUCLID_5:def 3;

        thus (( homography N) . P) = ( Dir |[(v `1 ), (v `2 ), (v `3 )]|) by A3, EUCLID_5: 3;

      end;

      hence thesis;

    end;

    theorem :: BKMODEL4:35

    

     Th26: for A be Subset of ( TOP-REAL 3) holds for B be convex non empty Subset of ( TOP-REAL 2) holds for r be Real holds for x be Element of ( TOP-REAL 3) st A = { x where x be Element of ( TOP-REAL 3) : |[(x `1 ), (x `2 )]| in B & (x `3 ) = r } holds A is non empty convex

    proof

      let A be Subset of ( TOP-REAL 3);

      let B be convex non empty Subset of ( TOP-REAL 2);

      let r be Real;

      let x be Element of ( TOP-REAL 3);

      assume

       A1: A = { x where x be Element of ( TOP-REAL 3) : |[(x `1 ), (x `2 )]| in B & (x `3 ) = r };

      

       A2: for z be Element of ( TOP-REAL 3) holds z in A iff |[(z `1 ), (z `2 )]| in B & (z `3 ) = r

      proof

        let z be Element of ( TOP-REAL 3);

        hereby

          assume z in A;

          then ex z9 be Element of ( TOP-REAL 3) st z = z9 & |[(z9 `1 ), (z9 `2 )]| in B & (z9 `3 ) = r by A1;

          hence |[(z `1 ), (z `2 )]| in B & (z `3 ) = r;

        end;

        assume |[(z `1 ), (z `2 )]| in B & (z `3 ) = r;

        hence z in A by A1;

      end;

      set y = the Element of B;

      reconsider z = |[(y `1 ), (y `2 ), r]| as Element of ( TOP-REAL 3);

      z = |[(z `1 ), (z `2 ), (z `3 )]| by EUCLID_5: 3;

      then

       A3: (z `1 ) = (y `1 ) & (z `2 ) = (y `2 ) & (z `3 ) = r by FINSEQ_1: 78;

      y in B;

      then |[(z `1 ), (z `2 )]| in B & (z `3 ) = r by A3, EUCLID: 53;

      then z in A by A1;

      hence A is non empty;

      now

        let u,v be Element of ( TOP-REAL 3);

        let s be Real;

        assume that

         A4: 0 < s < 1 and

         A5: u in A and

         A6: v in A;

        reconsider w = ((s * u) + ((1 - s) * v)) as Element of ( TOP-REAL 3);

        now

          reconsider su = (s * u), sv = ((1 - s) * v) as Element of ( TOP-REAL 3);

          su = |[(s * (u `1 )), (s * (u `2 )), (s * (u `3 ))]| & sv = |[((1 - s) * (v `1 )), ((1 - s) * (v `2 )), ((1 - s) * (v `3 ))]| by EUCLID_5: 7;

          

          then

           A7: |[((s * (u `1 )) + ((1 - s) * (v `1 ))), ((s * (u `2 )) + ((1 - s) * (v `2 ))), ((s * (u `3 )) + ((1 - s) * (v `3 )))]| = w by EUCLID_5: 6

          .= |[(w `1 ), (w `2 ), (w `3 )]| by EUCLID_5: 3;

          then

           A8: (w `1 ) = ((s * (u `1 )) + ((1 - s) * (v `1 ))) & (w `2 ) = ((s * (u `2 )) + ((1 - s) * (v `2 ))) & (w `3 ) = ((s * (u `3 )) + ((1 - s) * (v `3 ))) by FINSEQ_1: 78;

          (u `3 ) = r & (v `3 ) = r by A5, A6, A2;

          hence (w `3 ) = r by A7, FINSEQ_1: 78;

          reconsider u9 = |[(u `1 ), (u `2 )]|, v9 = |[(v `1 ), (v `2 )]|, w9 = |[(w `1 ), (w `2 )]| as Element of ( TOP-REAL 2);

          now

            thus u9 in B & v9 in B by A2, A6, A5;

            

            thus |[(w `1 ), (w `2 )]| = ( |[(s * (u `1 )), (s * (u `2 ))]| + |[((1 - s) * (v `1 )), ((1 - s) * (v `2 ))]|) by A8, EUCLID: 56

            .= ((s * |[(u `1 ), (u `2 )]|) + |[((1 - s) * (v `1 )), ((1 - s) * (v `2 ))]|) by EUCLID: 58

            .= ((s * u9) + ((1 - s) * v9)) by EUCLID: 58;

          end;

          hence |[(w `1 ), (w `2 )]| in B by A4, CONVEX1:def 2;

        end;

        hence ((s * u) + ((1 - s) * v)) in A by A1;

      end;

      hence A is convex by CONVEX1:def 2;

    end;

    theorem :: BKMODEL4:36

    

     Th27: for n1,n2,n3 be Element of F_Real holds for n,u be Element of ( TOP-REAL 3) st n = <*n1, n2, n3*> & (u . 3) = 1 holds |(n, u)| = (((n1 * (u . 1)) + (n2 * (u . 2))) + n3)

    proof

      let n1,n2,n3 be Element of F_Real ;

      let n,u be Element of ( TOP-REAL 3);

      assume that

       A1: n = <*n1, n2, n3*> and

       A2: (u . 3) = 1;

      n = |[(n `1 ), (n `2 ), (n `3 )]| by EUCLID_5: 3;

      then

       A3: (n `1 ) = n1 & (n `2 ) = n2 & (n `3 ) = n3 by A1, FINSEQ_1: 78;

       |(n, u)| = (((n1 * (u `1 )) + (n2 * (u `2 ))) + (n3 * (u `3 ))) by A3, EUCLID_5: 29

      .= (((n1 * (u . 1)) + (n2 * (u `2 ))) + (n3 * (u `3 ))) by EUCLID_5:def 1

      .= (((n1 * (u . 1)) + (n2 * (u . 2))) + (n3 * (u `3 ))) by EUCLID_5:def 2

      .= (((n1 * (u . 1)) + (n2 * (u . 2))) + (n3 * (u . 3))) by EUCLID_5:def 3;

      hence thesis by A2;

    end;

    theorem :: BKMODEL4:37

    

     Th28: for A be convex non empty Subset of ( TOP-REAL 3) holds for n,u,v be Element of ( TOP-REAL 3) st (for w be Element of ( TOP-REAL 3) st w in A holds |(n, w)| <> 0 ) & u in A & v in A holds 0 < ( |(n, u)| * |(n, v)|)

    proof

      let A be convex non empty Subset of ( TOP-REAL 3);

      let n,u,v be Element of ( TOP-REAL 3);

      assume that

       A1: for w be Element of ( TOP-REAL 3) st w in A holds |(n, w)| <> 0 and

       A2: u in A & v in A;

      set x = |(n, u)|, y = |(n, v)|;

      assume

       A3: not 0 < ( |(n, u)| * |(n, v)|);

      

       A4: x <> 0 & y <> 0 by A1, A2;

      then

       A5: 0 < (x / (x - y)) < 1 by A3, BKMODEL3: 1;

      reconsider l = (x / (x - y)) as non zero Real by A3, A4, BKMODEL3: 1;

      reconsider w = ((l * v) + ((1 - l) * u)) as Element of ( TOP-REAL 3);

      x <> y

      proof

        assume x = y;

        then l = 0 by XCMPLX_1: 49;

        hence contradiction;

      end;

      then

       A6: (1 - l) = ( - (y / (x - y))) by Th25;

       |(n, w)| = 0

      proof

         |(n, w)| = ( |(n, (l * v))| + |(n, ((1 - l) * u))|) by EUCLID_2: 26

        .= ((l * |(n, v)|) + |(n, ((1 - l) * u))|) by EUCLID_2: 19

        .= (((x / (x - y)) * y) + ((( - y) / (x - y)) * x)) by A6, EUCLID_2: 19;

        hence thesis;

      end;

      hence contradiction by A1, A2, A5, CONVEX1:def 2;

    end;

    theorem :: BKMODEL4:38

    

     Th29: for n31,n32,n33 be Element of F_Real holds for u,v be Element of ( TOP-REAL 2) st u in ( inside_of_circle ( 0 , 0 ,1)) & v in ( inside_of_circle ( 0 , 0 ,1)) & (for w be Element of ( TOP-REAL 2) st w in ( inside_of_circle ( 0 , 0 ,1)) holds (((n31 * (w . 1)) + (n32 * (w . 2))) + n33) <> 0 ) holds 0 < ((((n31 * (u . 1)) + (n32 * (u . 2))) + n33) * (((n31 * (v . 1)) + (n32 * (v . 2))) + n33))

    proof

      let n31,n32,n33 be Element of F_Real ;

      let u,v be Element of ( TOP-REAL 2);

      assume that

       A1: u in ( inside_of_circle ( 0 , 0 ,1)) and

       A2: v in ( inside_of_circle ( 0 , 0 ,1)) and

       A3: for w be Element of ( TOP-REAL 2) st w in ( inside_of_circle ( 0 , 0 ,1)) holds (((n31 * (w . 1)) + (n32 * (w . 2))) + n33) <> 0 ;

      set B = ( inside_of_circle ( 0 , 0 ,1));

      set A = { x where x be Element of ( TOP-REAL 3) : |[(x `1 ), (x `2 )]| in B & (x `3 ) = 1 };

      A c= the carrier of ( TOP-REAL 3)

      proof

        let x be object;

        assume x in A;

        then ex y be Element of ( TOP-REAL 3) st x = y & |[(y `1 ), (y `2 )]| in B & (y `3 ) = 1;

        hence thesis;

      end;

      then

      reconsider A as Subset of ( TOP-REAL 3);

      reconsider A as non empty convex Subset of ( TOP-REAL 3) by Th26;

      reconsider n = |[n31, n32, n33]|, u9 = |[(u . 1), (u . 2), 1]|, v9 = |[(v . 1), (v . 2), 1]| as Element of ( TOP-REAL 3);

      

       A4: |[(u `1 ), (u `2 )]| in B & |[(v `1 ), (v `2 )]| in B by A1, A2, EUCLID: 53;

      

       A5: (u9 `1 ) = (u . 1) & (u9 `2 ) = (u . 2) & (u9 `3 ) = 1 & (v9 `1 ) = (v . 1) & (v9 `2 ) = (v . 2) & (v9 `3 ) = 1 by EUCLID_5: 2;

      

       A6: u9 in A & v9 in A by A5, A4;

       A7:

      now

        let w be Element of ( TOP-REAL 3);

        assume w in A;

        then

        consider x be Element of ( TOP-REAL 3) such that

         A8: w = x and

         A9: |[(x `1 ), (x `2 )]| in B and

         A10: (x `3 ) = 1;

        reconsider v = |[(x `1 ), (x `2 )]| as Element of ( TOP-REAL 2);

        now

          (w . 3) = 1 by A8, A10, EUCLID_5:def 3;

          hence |(n, w)| = (((n31 * (w . 1)) + (n32 * (w . 2))) + n33) by Th27;

          

          thus (w . 1) = (w `1 ) by EUCLID_5:def 1

          .= (v `1 ) by A8, EUCLID: 52

          .= (v . 1);

          

          thus (w . 2) = (w `2 ) by EUCLID_5:def 2

          .= (v `2 ) by A8, EUCLID: 52

          .= (v . 2);

        end;

        hence |(n, w)| <> 0 by A3, A9;

      end;

      now

        n = <*n31, n32, n33*> & (u9 . 3) = 1 by A5, EUCLID_5:def 3;

        then |(n, u9)| = (((n31 * (u9 . 1)) + (n32 * (u9 . 2))) + n33) by Th27;

        then |(n, u9)| = (((n31 * (u9 `1 )) + (n32 * (u9 . 2))) + n33) by EUCLID_5:def 1;

        hence |(n, u9)| = (((n31 * (u . 1)) + (n32 * (u . 2))) + n33) by A5, EUCLID_5:def 2;

        n = <*n31, n32, n33*> & (v9 . 3) = 1 by A5, EUCLID_5:def 3;

        then |(n, v9)| = (((n31 * (v9 . 1)) + (n32 * (v9 . 2))) + n33) by Th27;

        then |(n, v9)| = (((n31 * (v9 `1 )) + (n32 * (v9 . 2))) + n33) by EUCLID_5:def 1;

        hence |(n, v9)| = (((n31 * (v . 1)) + (n32 * (v . 2))) + n33) by A5, EUCLID_5:def 2;

      end;

      hence thesis by A7, A6, Th28;

    end;

    theorem :: BKMODEL4:39

    

     Th30: for n31,n32,n33 be Element of F_Real holds for u,v be Element of ( TOP-REAL 2) st u in ( inside_of_circle ( 0 , 0 ,1)) & v in ( circle ( 0 , 0 ,1)) & (for w be Element of ( TOP-REAL 2) st w in ( closed_inside_of_circle ( 0 , 0 ,1)) holds (((n31 * (w . 1)) + (n32 * (w . 2))) + n33) <> 0 ) holds 0 < ((((n31 * (u . 1)) + (n32 * (u . 2))) + n33) * (((n31 * (v . 1)) + (n32 * (v . 2))) + n33))

    proof

      let n31,n32,n33 be Element of F_Real ;

      let u,v be Element of ( TOP-REAL 2);

      assume that

       A1: u in ( inside_of_circle ( 0 , 0 ,1)) and

       A2: v in ( circle ( 0 , 0 ,1)) and

       A3: for w be Element of ( TOP-REAL 2) st w in ( closed_inside_of_circle ( 0 , 0 ,1)) holds (((n31 * (w . 1)) + (n32 * (w . 2))) + n33) <> 0 ;

      set B = ( closed_inside_of_circle ( 0 , 0 ,1));

      set A = { x where x be Element of ( TOP-REAL 3) : |[(x `1 ), (x `2 )]| in B & (x `3 ) = 1 };

      A c= the carrier of ( TOP-REAL 3)

      proof

        let x be object;

        assume x in A;

        then ex y be Element of ( TOP-REAL 3) st x = y & |[(y `1 ), (y `2 )]| in B & (y `3 ) = 1;

        hence thesis;

      end;

      then

      reconsider A as Subset of ( TOP-REAL 3);

      reconsider A as non empty convex Subset of ( TOP-REAL 3) by Th26;

      reconsider n = |[n31, n32, n33]|, u9 = |[(u . 1), (u . 2), 1]|, v9 = |[(v . 1), (v . 2), 1]| as Element of ( TOP-REAL 3);

      ( inside_of_circle ( 0 , 0 ,1)) c= ( closed_inside_of_circle ( 0 , 0 ,1)) & ( circle ( 0 , 0 ,1)) c= ( closed_inside_of_circle ( 0 , 0 ,1)) by TOPREAL9: 46, TOPREAL9: 53;

      then u in B & v in B by A1, A2;

      then

       A4: |[(u `1 ), (u `2 )]| in B & |[(v `1 ), (v `2 )]| in B by EUCLID: 53;

      

       A5: (u9 `1 ) = (u . 1) & (u9 `2 ) = (u . 2) & (u9 `3 ) = 1 & (v9 `1 ) = (v . 1) & (v9 `2 ) = (v . 2) & (v9 `3 ) = 1 by EUCLID_5: 2;

      

       A6: u9 in A & v9 in A by A5, A4;

       A7:

      now

        let w be Element of ( TOP-REAL 3);

        assume w in A;

        then

        consider x be Element of ( TOP-REAL 3) such that

         A8: w = x and

         A9: |[(x `1 ), (x `2 )]| in B and

         A10: (x `3 ) = 1;

        reconsider v = |[(x `1 ), (x `2 )]| as Element of ( TOP-REAL 2);

        now

          (w . 3) = 1 by A8, A10, EUCLID_5:def 3;

          hence |(n, w)| = (((n31 * (w . 1)) + (n32 * (w . 2))) + n33) by Th27;

          

          thus (w . 1) = (w `1 ) by EUCLID_5:def 1

          .= (v `1 ) by A8, EUCLID: 52

          .= (v . 1);

          

          thus (w . 2) = (w `2 ) by EUCLID_5:def 2

          .= (v `2 ) by A8, EUCLID: 52

          .= (v . 2);

        end;

        hence |(n, w)| <> 0 by A3, A9;

      end;

      now

        n = <*n31, n32, n33*> & (u9 . 3) = 1 by A5, EUCLID_5:def 3;

        then |(n, u9)| = (((n31 * (u9 . 1)) + (n32 * (u9 . 2))) + n33) by Th27;

        then |(n, u9)| = (((n31 * (u9 `1 )) + (n32 * (u9 . 2))) + n33) by EUCLID_5:def 1;

        hence |(n, u9)| = (((n31 * (u . 1)) + (n32 * (u . 2))) + n33) by A5, EUCLID_5:def 2;

        n = <*n31, n32, n33*> & (v9 . 3) = 1 by A5, EUCLID_5:def 3;

        then |(n, v9)| = (((n31 * (v9 . 1)) + (n32 * (v9 . 2))) + n33) by Th27;

        then |(n, v9)| = (((n31 * (v9 `1 )) + (n32 * (v9 . 2))) + n33) by EUCLID_5:def 1;

        hence |(n, v9)| = (((n31 * (v . 1)) + (n32 * (v . 2))) + n33) by A5, EUCLID_5:def 2;

      end;

      hence thesis by A7, A6, Th28;

    end;

    theorem :: BKMODEL4:40

    

     Th34: for l,r be Real holds for u,v,w be Element of ( TOP-REAL 3) holds for n11,n12,n13,n21,n22,n23,n31,n32,n33,nu1,nu2,nu3,nv1,nv2,nv3,nw1,nw2,nw3 be Real st nu3 <> 0 & nv3 <> 0 & nw3 <> 0 & r = ((l * nv3) / (((1 - l) * nu3) + (l * nv3))) & (((1 - l) * nu3) + (l * nv3)) <> 0 & w = (((1 - l) * u) + (l * v)) & nu1 = (((n11 * (u . 1)) + (n12 * (u . 2))) + n13) & nu2 = (((n21 * (u . 1)) + (n22 * (u . 2))) + n23) & nu3 = (((n31 * (u . 1)) + (n32 * (u . 2))) + n33) & nv1 = (((n11 * (v . 1)) + (n12 * (v . 2))) + n13) & nv2 = (((n21 * (v . 1)) + (n22 * (v . 2))) + n23) & nv3 = (((n31 * (v . 1)) + (n32 * (v . 2))) + n33) & nw1 = (((n11 * (w . 1)) + (n12 * (w . 2))) + n13) & nw2 = (((n21 * (w . 1)) + (n22 * (w . 2))) + n23) & nw3 = (((n31 * (w . 1)) + (n32 * (w . 2))) + n33) holds (((1 - r) * |[(nu1 / nu3), (nu2 / nu3), 1]|) + (r * |[(nv1 / nv3), (nv2 / nv3), 1]|)) = |[(nw1 / nw3), (nw2 / nw3), 1]|

    proof

      let l,r be Real;

      let u,v,w be Element of ( TOP-REAL 3);

      let n11,n12,n13,n21,n22,n23,n31,n32,n33,nu1,nu2,nu3,nv1,nv2,nv3,nw1,nw2,nw3 be Real;

      assume

       A1: nu3 <> 0 & nv3 <> 0 & nw3 <> 0 & r = ((l * nv3) / (((1 - l) * nu3) + (l * nv3))) & (((1 - l) * nu3) + (l * nv3)) <> 0 & w = (((1 - l) * u) + (l * v)) & nu1 = (((n11 * (u . 1)) + (n12 * (u . 2))) + n13) & nu2 = (((n21 * (u . 1)) + (n22 * (u . 2))) + n23) & nu3 = (((n31 * (u . 1)) + (n32 * (u . 2))) + n33) & nv1 = (((n11 * (v . 1)) + (n12 * (v . 2))) + n13) & nv2 = (((n21 * (v . 1)) + (n22 * (v . 2))) + n23) & nv3 = (((n31 * (v . 1)) + (n32 * (v . 2))) + n33) & nw1 = (((n11 * (w . 1)) + (n12 * (w . 2))) + n13) & nw2 = (((n21 * (w . 1)) + (n22 * (w . 2))) + n23) & nw3 = (((n31 * (w . 1)) + (n32 * (w . 2))) + n33);

      reconsider lu = ((1 - l) * u), lv = (l * v) as Element of ( TOP-REAL 3);

      reconsider ru = ((1 - l) * u), rv = (l * v) as Element of ( REAL 3) by EUCLID: 22;

       A2:

      now

        

        thus ((lu + lv) . 1) = ((ru . 1) + (rv . 1)) by RVSUM_1: 11

        .= ((lu . 1) + (lv . 1));

        

        thus ((lu + lv) . 2) = ((ru . 2) + (rv . 2)) by RVSUM_1: 11

        .= ((lu . 2) + (lv . 2));

        

        thus ((lu + lv) . 3) = ((ru . 3) + (rv . 3)) by RVSUM_1: 11

        .= ((lu . 3) + (lv . 3));

      end;

       A3:

      now

        

        thus (w . 1) = (((1 - l) * (u . 1)) + ((l * v) . 1)) by A1, A2, RVSUM_1: 44

        .= (((1 - l) * (u . 1)) + (l * (v . 1))) by RVSUM_1: 44;

        

        thus (w . 2) = (((1 - l) * (u . 2)) + ((l * v) . 2)) by A1, A2, RVSUM_1: 44

        .= (((1 - l) * (u . 2)) + (l * (v . 2))) by RVSUM_1: 44;

        

        thus (w . 3) = (((1 - l) * (u . 3)) + ((l * v) . 3)) by A1, A2, RVSUM_1: 44

        .= (((1 - l) * (u . 3)) + (l * (v . 3))) by RVSUM_1: 44;

      end;

       A4:

      now

        now

          

          thus (((1 - r) * nu1) / nu3) = (((((1 - l) * nu3) / (((1 - l) * nu3) + (l * nv3))) * nu1) / nu3) by A1, Th32

          .= (((1 - l) * nu1) / (((1 - l) * nu3) + (l * nv3))) by A1, Th33;

          thus ((r * nv1) / nv3) = ((l * nv1) / (((1 - l) * nu3) + (l * nv3))) by A1, Th33;

        end;

        

        hence ((((1 - r) * nu1) / nu3) + ((r * nv1) / nv3)) = ((((1 - l) * nu1) + (l * nv1)) / (((1 - l) * nu3) + (l * nv3)))

        .= (nw1 / nw3) by A1, A3;

        now

          

          thus (((1 - r) * nu2) / nu3) = (((((1 - l) * nu3) / (((1 - l) * nu3) + (l * nv3))) * nu2) / nu3) by A1, Th32

          .= (((1 - l) * nu2) / (((1 - l) * nu3) + (l * nv3))) by A1, Th33;

          thus ((r * nv2) / nv3) = ((l * nv2) / (((1 - l) * nu3) + (l * nv3))) by A1, Th33;

        end;

        

        hence ((((1 - r) * nu2) / nu3) + ((r * nv2) / nv3)) = ((((1 - l) * nu2) + (l * nv2)) / (((1 - l) * nu3) + (l * nv3)))

        .= (nw2 / nw3) by A1, A3;

      end;

      (((1 - r) * |[(nu1 / nu3), (nu2 / nu3), 1]|) + (r * |[(nv1 / nv3), (nv2 / nv3), 1]|)) = ( |[((1 - r) * (nu1 / nu3)), ((1 - r) * (nu2 / nu3)), ((1 - r) * 1)]| + (r * |[(nv1 / nv3), (nv2 / nv3), 1]|)) by EUCLID_5: 8

      .= ( |[(((1 - r) * nu1) / nu3), (((1 - r) * nu2) / nu3), (1 - r)]| + |[(r * (nv1 / nv3)), (r * (nv2 / nv3)), (r * 1)]|) by EUCLID_5: 8

      .= |[((((1 - r) * nu1) / nu3) + ((r * nv1) / nv3)), ((((1 - r) * nu2) / nu3) + ((r * nv2) / nv3)), ((1 - r) + r)]| by EUCLID_5: 6

      .= |[(nw1 / nw3), (nw2 / nw3), 1]| by A4;

      hence thesis;

    end;

    theorem :: BKMODEL4:41

    for N be invertible Matrix of 3, F_Real holds for h be Element of SubGroupK-isometry holds for n11,n12,n13,n21,n22,n23,n31,n32,n33 be Element of F_Real holds for P be Element of BK_model st h = ( homography N) & N = <* <*n11, n12, n13*>, <*n21, n22, n23*>, <*n31, n32, n33*>*> holds (( homography N) . P) = ( Dir |[((((n11 * (( BK_to_REAL2 P) `1 )) + (n12 * (( BK_to_REAL2 P) `2 ))) + n13) / (((n31 * (( BK_to_REAL2 P) `1 )) + (n32 * (( BK_to_REAL2 P) `2 ))) + n33)), ((((n21 * (( BK_to_REAL2 P) `1 )) + (n22 * (( BK_to_REAL2 P) `2 ))) + n23) / (((n31 * (( BK_to_REAL2 P) `1 )) + (n32 * (( BK_to_REAL2 P) `2 ))) + n33)), 1]|)

    proof

      let N be invertible Matrix of 3, F_Real ;

      let h be Element of SubGroupK-isometry ;

      let n11,n12,n13,n21,n22,n23,n31,n32,n33 be Element of F_Real ;

      let P be Element of BK_model ;

      assume

       A1: h = ( homography N) & N = <* <*n11, n12, n13*>, <*n21, n22, n23*>, <*n31, n32, n33*>*>;

      consider u be non zero Element of ( TOP-REAL 3) such that

       A2: P = ( Dir u) & (u . 3) = 1 & ( BK_to_REAL2 P) = |[(u . 1), (u . 2)]| by BKMODEL2:def 2;

      (( BK_to_REAL2 P) `1 ) = (u . 1) & (( BK_to_REAL2 P) `2 ) = (u . 2) & (( homography N) . P) = ( Dir |[((((n11 * (u . 1)) + (n12 * (u . 2))) + n13) / (((n31 * (u . 1)) + (n32 * (u . 2))) + n33)), ((((n21 * (u . 1)) + (n22 * (u . 2))) + n23) / (((n31 * (u . 1)) + (n32 * (u . 2))) + n33)), 1]|) by A1, A2, Th23, EUCLID: 52;

      hence thesis;

    end;

    theorem :: BKMODEL4:42

    

     Th36: for h be Element of SubGroupK-isometry holds for N be invertible Matrix of 3, F_Real holds for n11,n12,n13,n21,n22,n23,n31,n32,n33 be Element of F_Real holds for u2 be Element of ( TOP-REAL 2) st h = ( homography N) & N = <* <*n11, n12, n13*>, <*n21, n22, n23*>, <*n31, n32, n33*>*> & u2 in ( inside_of_circle ( 0 , 0 ,1)) holds (((n31 * (u2 . 1)) + (n32 * (u2 . 2))) + n33) <> 0

    proof

      let h be Element of SubGroupK-isometry ;

      let N be invertible Matrix of 3, F_Real ;

      let n11,n12,n13,n21,n22,n23,n31,n32,n33 be Element of F_Real ;

      let u2 be Element of ( TOP-REAL 2);

      assume that

       A1: h = ( homography N) and

       A2: N = <* <*n11, n12, n13*>, <*n21, n22, n23*>, <*n31, n32, n33*>*> and

       A3: u2 in ( inside_of_circle ( 0 , 0 ,1));

      reconsider uic = u2 as Element of ( inside_of_circle ( 0 , 0 ,1)) by A3;

      consider Q be Element of ( TOP-REAL 2) such that

       A4: Q = uic & ( REAL2_to_BK uic) = ( Dir |[(Q `1 ), (Q `2 ), 1]|) by BKMODEL2:def 3;

      reconsider P = ( REAL2_to_BK uic) as Element of BK_model ;

      reconsider v = |[(Q `1 ), (Q `2 ), 1]| as non zero Element of ( TOP-REAL 3);

      

       A5: (v . 1) = (v `1 ) by EUCLID_5:def 1

      .= (u2 . 1) by A4, EUCLID_5: 2;

      

       A6: (v . 2) = (v `2 ) by EUCLID_5:def 2

      .= (u2 . 2) by A4, EUCLID_5: 2;

      now

        thus P = ( Dir v) by A4;

        

        thus (v . 3) = (v `3 ) by EUCLID_5:def 3

        .= 1 by EUCLID_5: 2;

      end;

      hence thesis by A5, A6, A1, A2, Th20;

    end;

    

     Lem01: (( 0 ^2 ) + ( 0 ^2 )) = 0

    proof

      (( 0 ^2 ) + ( 0 ^2 )) = (( 0 * 0 ) + ( 0 ^2 )) by SQUARE_1:def 1

      .= ( 0 * 0 ) by SQUARE_1:def 1;

      hence thesis;

    end;

    theorem :: BKMODEL4:43

    

     Th37: for r be positive Real holds for u be Element of ( TOP-REAL 2) st u in ( circle ( 0 , 0 ,r)) holds u is non zero

    proof

      let r be positive Real;

      let u be Element of ( TOP-REAL 2);

      assume

       A1: u in ( circle ( 0 , 0 ,r));

      assume u is zero;

      then (r ^2 ) = 0 by A1, BKMODEL1: 14, EUCLID: 54, Lem01;

      hence contradiction;

    end;

    theorem :: BKMODEL4:44

    

     Th38: for h be Element of SubGroupK-isometry holds for N be invertible Matrix of 3, F_Real holds for n11,n12,n13,n21,n22,n23,n31,n32,n33 be Element of F_Real holds for u2 be Element of ( TOP-REAL 2) st h = ( homography N) & N = <* <*n11, n12, n13*>, <*n21, n22, n23*>, <*n31, n32, n33*>*> & u2 in ( closed_inside_of_circle ( 0 , 0 ,1)) holds (((n31 * (u2 . 1)) + (n32 * (u2 . 2))) + n33) <> 0

    proof

      let h be Element of SubGroupK-isometry ;

      let N be invertible Matrix of 3, F_Real ;

      let n11,n12,n13,n21,n22,n23,n31,n32,n33 be Element of F_Real ;

      let u2 be Element of ( TOP-REAL 2);

      assume that

       A1: h = ( homography N) and

       A2: N = <* <*n11, n12, n13*>, <*n21, n22, n23*>, <*n31, n32, n33*>*> and

       A3: u2 in ( closed_inside_of_circle ( 0 , 0 ,1));

      u2 in (( inside_of_circle ( 0 , 0 ,1)) \/ ( circle ( 0 , 0 ,1))) by A3, TOPREAL9: 55;

      per cases by XBOOLE_0:def 3;

        suppose u2 in ( inside_of_circle ( 0 , 0 ,1));

        then

        reconsider uic = u2 as Element of ( inside_of_circle ( 0 , 0 ,1));

        consider Q be Element of ( TOP-REAL 2) such that

         A4: Q = uic & ( REAL2_to_BK uic) = ( Dir |[(Q `1 ), (Q `2 ), 1]|) by BKMODEL2:def 3;

        reconsider P = ( REAL2_to_BK uic) as Element of BK_model ;

        reconsider v = |[(Q `1 ), (Q `2 ), 1]| as non zero Element of ( TOP-REAL 3);

        

         A5: (v . 1) = (v `1 ) by EUCLID_5:def 1

        .= (u2 . 1) by A4, EUCLID_5: 2;

        

         A6: (v . 2) = (v `2 ) by EUCLID_5:def 2

        .= (u2 . 2) by A4, EUCLID_5: 2;

        now

          thus P = ( Dir v) by A4;

          

          thus (v . 3) = (v `3 ) by EUCLID_5:def 3

          .= 1 by EUCLID_5: 2;

        end;

        hence thesis by A5, A6, A1, A2, Th20;

      end;

        suppose

         A7: u2 in ( circle ( 0 , 0 ,1));

        then

        reconsider u2 as non zero Element of ( TOP-REAL 2) by Th37;

        reconsider P = ( REAL2_to_absolute u2) as Element of absolute ;

        reconsider v = |[(u2 . 1), (u2 . 2), 1]| as non zero Element of ( TOP-REAL 3);

        

         A8: (v . 1) = (v `1 ) by EUCLID_5:def 1

        .= (u2 . 1) by EUCLID_5: 2;

        

         A9: (v . 2) = (v `2 ) by EUCLID_5:def 2

        .= (u2 . 2) by EUCLID_5: 2;

        now

          thus P is Element of absolute ;

          thus P = ( Dir v) by A7, BKMODEL1:def 9;

          

          thus (v . 3) = (v `3 ) by EUCLID_5:def 3

          .= 1 by EUCLID_5: 2;

        end;

        hence thesis by A8, A9, A1, A2, Th22;

      end;

    end;

    theorem :: BKMODEL4:45

    

     Th39: for a,b,c,d,e,f,r be Real st (((1 - r) * |[a, b, 1]|) + (r * |[c, d, 1]|)) = |[e, f, 1]| holds (((1 - r) * |[a, b]|) + (r * |[c, d]|)) = |[e, f]|

    proof

      let a,b,c,d,e,f,r be Real;

      assume (((1 - r) * |[a, b, 1]|) + (r * |[c, d, 1]|)) = |[e, f, 1]|;

      

      then |[e, f, 1]| = ( |[((1 - r) * a), ((1 - r) * b), ((1 - r) * 1)]| + (r * |[c, d, 1]|)) by EUCLID_5: 8

      .= ( |[((1 - r) * a), ((1 - r) * b), (1 - r)]| + |[(r * c), (r * d), (r * 1)]|) by EUCLID_5: 8

      .= |[(((1 - r) * a) + (r * c)), (((1 - r) * b) + (r * d)), ((1 - r) + r)]| by EUCLID_5: 6;

      then e = (((1 - r) * a) + (r * c)) & f = (((1 - r) * b) + (r * d)) by FINSEQ_1: 78;

      

      then |[e, f]| = ( |[((1 - r) * a), ((1 - r) * b)]| + |[(r * c), (r * d)]|) by EUCLID: 56

      .= (((1 - r) * |[a, b]|) + |[(r * c), (r * d)]|) by EUCLID: 58

      .= (((1 - r) * |[a, b]|) + (r * |[c, d]|)) by EUCLID: 58;

      hence thesis;

    end;

    theorem :: BKMODEL4:46

    for P,Q,R,P9,Q9,R9 be POINT of BK-model-Plane holds for p,q,r,p9,q9,r9 be Element of BK_model holds for h be Element of SubGroupK-isometry holds for N be invertible Matrix of 3, F_Real st h = ( homography N) & between (P,Q,R) & P = p & Q = q & R = r & p9 = (( homography N) . p) & q9 = (( homography N) . q) & r9 = (( homography N) . r) & P9 = p9 & Q9 = q9 & R9 = r9 holds between (P9,Q9,R9)

    proof

      let P,Q,R,P9,Q9,R9 be POINT of BK-model-Plane ;

      let p,q,r,p9,q9,r9 be Element of BK_model ;

      let h be Element of SubGroupK-isometry ;

      let N be invertible Matrix of 3, F_Real ;

      assume that

       A1: h = ( homography N) and

       A2: between (P,Q,R) and

       A3: P = p and

       A4: Q = q and

       A5: R = r and

       A6: p9 = (( homography N) . p) and

       A7: q9 = (( homography N) . q) and

       A8: r9 = (( homography N) . r) and

       A9: P9 = p9 and

       A10: Q9 = q9 and

       A11: R9 = r9;

      consider n11,n12,n13,n21,n22,n23,n31,n32,n33 be Element of F_Real such that

       A12: N = <* <*n11, n12, n13*>, <*n21, n22, n23*>, <*n31, n32, n33*>*> by PASCAL: 3;

      consider u be non zero Element of ( TOP-REAL 3) such that

       A13: ( Dir u) = p & (u . 3) = 1 & ( BK_to_REAL2 p) = |[(u . 1), (u . 2)]| by BKMODEL2:def 2;

      consider v be non zero Element of ( TOP-REAL 3) such that

       A14: ( Dir v) = r & (v . 3) = 1 & ( BK_to_REAL2 r) = |[(v . 1), (v . 2)]| by BKMODEL2:def 2;

      consider w be non zero Element of ( TOP-REAL 3) such that

       A15: ( Dir w) = q & (w . 3) = 1 & ( BK_to_REAL2 q) = |[(w . 1), (w . 2)]| by BKMODEL2:def 2;

      reconsider nu1 = (((n11 * (u . 1)) + (n12 * (u . 2))) + n13), nu2 = (((n21 * (u . 1)) + (n22 * (u . 2))) + n23), nu3 = (((n31 * (u . 1)) + (n32 * (u . 2))) + n33), nv1 = (((n11 * (v . 1)) + (n12 * (v . 2))) + n13), nv2 = (((n21 * (v . 1)) + (n22 * (v . 2))) + n23), nv3 = (((n31 * (v . 1)) + (n32 * (v . 2))) + n33), nw1 = (((n11 * (w . 1)) + (n12 * (w . 2))) + n13), nw2 = (((n21 * (w . 1)) + (n22 * (w . 2))) + n23), nw3 = (((n31 * (w . 1)) + (n32 * (w . 2))) + n33) as Real;

      

       A16: ( BK_to_T2 P) = ( BK_to_REAL2 p) & ( Tn2TR ( BK_to_T2 P)) = ( BK_to_REAL2 p) & ( BK_to_T2 Q) = ( BK_to_REAL2 q) & ( Tn2TR ( BK_to_T2 Q)) = ( BK_to_REAL2 q) & ( BK_to_T2 R) = ( BK_to_REAL2 r) & ( Tn2TR ( BK_to_T2 R)) = ( BK_to_REAL2 r) by A3, A4, A5, Th04;

      then ( Tn2TR ( BK_to_T2 Q)) in ( LSeg (( Tn2TR ( BK_to_T2 P)),( Tn2TR ( BK_to_T2 R)))) by A2, A3, A4, A5, BKMODEL3:def 7;

      then

      consider l be Real such that

       A17: 0 <= l & l <= 1 and

       A18: ( Tn2TR ( BK_to_T2 Q)) = (((1 - l) * ( Tn2TR ( BK_to_T2 P))) + (l * ( Tn2TR ( BK_to_T2 R)))) by RLTOPSP1: 76;

       |[(w . 1), (w . 2)]| = ( |[((1 - l) * (u . 1)), ((1 - l) * (u . 2))]| + (l * |[(v . 1), (v . 2)]|)) by A18, A16, A13, A14, A15, EUCLID: 58

      .= ( |[((1 - l) * (u . 1)), ((1 - l) * (u . 2))]| + |[(l * (v . 1)), (l * (v . 2))]|) by EUCLID: 58

      .= |[(((1 - l) * (u . 1)) + (l * (v . 1))), (((1 - l) * (u . 2)) + (l * (v . 2)))]| by EUCLID: 56;

      then

       A19: (w . 1) = (((1 - l) * (u . 1)) + (l * (v . 1))) & (w . 2) = (((1 - l) * (u . 2)) + (l * (v . 2))) by FINSEQ_1: 77;

      set r = ((l * nv3) / (((1 - l) * nu3) + (l * nv3)));

      now

        

        thus w = |[(w `1 ), (w `2 ), (w `3 )]| by EUCLID_5: 3

        .= |[(w . 1), (w `2 ), (w `3 )]| by EUCLID_5:def 1

        .= |[(w . 1), (w . 2), (w `3 )]| by EUCLID_5:def 2

        .= |[(((1 - l) * (u . 1)) + (l * (v . 1))), (((1 - l) * (u . 2)) + (l * (v . 2))), (((1 - l) * 1) + (l * 1))]| by A15, A19, EUCLID_5:def 3

        .= ( |[((1 - l) * (u . 1)), ((1 - l) * (u . 2)), ((1 - l) * 1)]| + |[(l * (v . 1)), (l * (v . 2)), (l * 1)]|) by EUCLID_5: 6

        .= (((1 - l) * |[(u . 1), (u . 2), 1]|) + |[(l * (v . 1)), (l * (v . 2)), (l * 1)]|) by EUCLID_5: 8

        .= (((1 - l) * |[(u . 1), (u . 2), 1]|) + (l * |[(v . 1), (v . 2), 1]|)) by EUCLID_5: 8

        .= (((1 - l) * u) + (l * |[(v . 1), (v . 2), (v . 3)]|)) by A13, A14, Th35

        .= (((1 - l) * u) + (l * v)) by Th35;

        thus nu3 <> 0 by A1, A12, A13, Th20;

        thus nv3 <> 0 by A1, A12, A14, Th20;

        thus

         A20: nw3 <> 0 by A1, A12, A15, Th20;

        thus nw3 = (((1 - l) * nu3) + (l * nv3)) by A19;

        thus (((1 - l) * nu3) + (l * nv3)) <> 0 by A19, A20;

      end;

      then

       A21: (((1 - r) * |[(nu1 / nu3), (nu2 / nu3), 1]|) + (r * |[(nv1 / nv3), (nv2 / nv3), 1]|)) = |[(nw1 / nw3), (nw2 / nw3), 1]| by Th34;

      

       A22: 0 <= r <= 1

      proof

        now

          thus 0 <= l <= 1 by A17;

          thus 0 < (nu3 * nv3)

          proof

            reconsider u1 = |[(u . 1), (u . 2)]|, v1 = |[(v . 1), (v . 2)]| as Element of ( TOP-REAL 2);

            

             A23: (u1 . 1) = (u1 `1 )

            .= (u . 1) by EUCLID: 52;

            

             A24: (u1 . 2) = (u1 `2 )

            .= (u . 2) by EUCLID: 52;

            

             A25: (v1 . 1) = (v1 `1 )

            .= (v . 1) by EUCLID: 52;

            

             A26: (v1 . 2) = (v1 `2 )

            .= (v . 2) by EUCLID: 52;

            reconsider m31 = n31, m32 = n32, m33 = n33 as Element of F_Real ;

            u1 in ( inside_of_circle ( 0 , 0 ,1)) & v1 in ( inside_of_circle ( 0 , 0 ,1)) & for w1 be Element of ( TOP-REAL 2) st w1 in ( inside_of_circle ( 0 , 0 ,1)) holds (((m31 * (w1 . 1)) + (m32 * (w1 . 2))) + m33) <> 0 by A13, A14, A1, A12, Th36;

            hence thesis by A23, A24, A25, A26, Th29;

          end;

        end;

        hence thesis by Th31;

      end;

      

       A27: ( BK_to_T2 P9) = ( BK_to_REAL2 p9) & ( Tn2TR ( BK_to_T2 P9)) = ( BK_to_REAL2 p9) & ( BK_to_T2 Q9) = ( BK_to_REAL2 q9) & ( Tn2TR ( BK_to_T2 Q9)) = ( BK_to_REAL2 q9) & ( BK_to_T2 R9) = ( BK_to_REAL2 r9) & ( Tn2TR ( BK_to_T2 R9)) = ( BK_to_REAL2 r9) by A9, A10, A11, Th04;

      now

        thus 0 <= r <= 1 by A22;

        thus ( Tn2TR ( BK_to_T2 Q9)) = (((1 - r) * ( Tn2TR ( BK_to_T2 P9))) + (r * ( Tn2TR ( BK_to_T2 R9))))

        proof

          reconsider u2 = |[(nu1 / nu3), (nu2 / nu3), 1]| as non zero Element of ( TOP-REAL 3);

          consider u3 be non zero Element of ( TOP-REAL 3) such that

           A28: ( Dir u3) = p9 & (u3 . 3) = 1 & ( BK_to_REAL2 p9) = |[(u3 . 1), (u3 . 2)]| by BKMODEL2:def 2;

          now

            thus ( Dir u3) = ( Dir u2) by A28, A6, A1, A12, A13, Th23;

            

            thus (u2 . 3) = (u2 `3 ) by EUCLID_5:def 3

            .= 1 by EUCLID_5: 2;

            hence (u2 . 3) = (u3 . 3) by A28;

          end;

          then u2 = u3 by BKMODEL1: 43;

          

          then

           A29: ( BK_to_REAL2 p9) = |[(u2 `1 ), (u2 . 2)]| by A28, EUCLID_5:def 1

          .= |[(u2 `1 ), (u2 `2 )]| by EUCLID_5:def 2

          .= |[(nu1 / nu3), (u2 `2 )]| by EUCLID_5: 2

          .= |[(nu1 / nu3), (nu2 / nu3)]| by EUCLID_5: 2;

          reconsider v2 = |[(nv1 / nv3), (nv2 / nv3), 1]| as non zero Element of ( TOP-REAL 3);

          consider v3 be non zero Element of ( TOP-REAL 3) such that

           A30: ( Dir v3) = r9 & (v3 . 3) = 1 & ( BK_to_REAL2 r9) = |[(v3 . 1), (v3 . 2)]| by BKMODEL2:def 2;

          now

            thus ( Dir v3) = ( Dir v2) by A30, A1, A12, A14, Th23, A8;

            

            thus (v2 . 3) = (v2 `3 ) by EUCLID_5:def 3

            .= 1 by EUCLID_5: 2;

            hence (v2 . 3) = (v3 . 3) by A30;

          end;

          then v2 = v3 by BKMODEL1: 43;

          

          then

           A31: ( BK_to_REAL2 r9) = |[(v2 `1 ), (v2 . 2)]| by A30, EUCLID_5:def 1

          .= |[(v2 `1 ), (v2 `2 )]| by EUCLID_5:def 2

          .= |[(nv1 / nv3), (v2 `2 )]| by EUCLID_5: 2

          .= |[(nv1 / nv3), (nv2 / nv3)]| by EUCLID_5: 2;

          reconsider w2 = |[(nw1 / nw3), (nw2 / nw3), 1]| as non zero Element of ( TOP-REAL 3);

          consider w3 be non zero Element of ( TOP-REAL 3) such that

           A32: ( Dir w3) = q9 & (w3 . 3) = 1 & ( BK_to_REAL2 q9) = |[(w3 . 1), (w3 . 2)]| by BKMODEL2:def 2;

          now

            thus ( Dir w3) = ( Dir w2) by A32, A1, A12, A15, Th23, A7;

            

            thus (w2 . 3) = (w2 `3 ) by EUCLID_5:def 3

            .= 1 by EUCLID_5: 2;

            hence (w2 . 3) = (w3 . 3) by A32;

          end;

          then w2 = w3 by BKMODEL1: 43;

          

          then ( BK_to_REAL2 q9) = |[(w2 `1 ), (w2 . 2)]| by A32, EUCLID_5:def 1

          .= |[(w2 `1 ), (w2 `2 )]| by EUCLID_5:def 2

          .= |[(nw1 / nw3), (w2 `2 )]| by EUCLID_5: 2

          .= |[(nw1 / nw3), (nw2 / nw3)]| by EUCLID_5: 2;

          hence thesis by A27, A29, A31, Th39, A21;

        end;

      end;

      then ( Tn2TR ( BK_to_T2 Q9)) in { (((1 - r) * ( Tn2TR ( BK_to_T2 P9))) + (r * ( Tn2TR ( BK_to_T2 R9)))) where r be Real : 0 <= r & r <= 1 };

      then ( Tn2TR ( BK_to_T2 Q9)) in ( LSeg (( Tn2TR ( BK_to_T2 P9)),( Tn2TR ( BK_to_T2 R9)))) by RLTOPSP1:def 2;

      hence thesis by A27, A9, A10, A11, BKMODEL3:def 7;

    end;

    definition

      let P be Point of ( ProjectiveSpace ( TOP-REAL 3));

      :: BKMODEL4:def4

      attr P is point_at_infty means

      : Def04: ex u be non zero Element of ( TOP-REAL 3) st P = ( Dir u) & (u `3 ) = 0 ;

    end

    theorem :: BKMODEL4:47

    

     Th40: for P be Point of ( ProjectiveSpace ( TOP-REAL 3)) st ex u be non zero Element of ( TOP-REAL 3) st P = ( Dir u) & (u `3 ) <> 0 holds P is non point_at_infty

    proof

      let P be Point of ( ProjectiveSpace ( TOP-REAL 3));

      given u be non zero Element of ( TOP-REAL 3) such that

       A1: P = ( Dir u) and

       A2: (u `3 ) <> 0 ;

      now

        let v be non zero Element of ( TOP-REAL 3);

        assume P = ( Dir v);

        then are_Prop (u,v) by A1, ANPROJ_1: 22;

        then

        consider a be Real such that

         A3: a <> 0 and

         A4: v = (a * u) by ANPROJ_1: 1;

        (v `3 ) = (a * (u `3 )) by A4, EUCLID_5: 9;

        hence (v `3 ) <> 0 by A2, A3;

      end;

      hence thesis;

    end;

    registration

      cluster point_at_infty for Point of ( ProjectiveSpace ( TOP-REAL 3));

      existence

      proof

        reconsider u = |[1, 0 , 0 ]| as non zero Element of ( TOP-REAL 3);

        reconsider P = ( Dir u) as Point of ( ProjectiveSpace ( TOP-REAL 3)) by ANPROJ_1: 26;

        take P;

        (u `3 ) = 0 by EUCLID_5: 2;

        hence thesis;

      end;

      cluster non point_at_infty for Point of ( ProjectiveSpace ( TOP-REAL 3));

      correctness

      proof

        reconsider u = |[ 0 , 0 , 1]| as non zero Element of ( TOP-REAL 3);

        reconsider P = ( Dir u) as Point of ( ProjectiveSpace ( TOP-REAL 3)) by ANPROJ_1: 26;

        take P;

        now

          let v be non zero Element of ( TOP-REAL 3);

          assume P = ( Dir v);

          then are_Prop (u,v) by ANPROJ_1: 22;

          then

          consider a be Real such that

           A1: a <> 0 and

           A2: v = (a * u) by ANPROJ_1: 1;

          (v `3 ) = (a * (u `3 )) by A2, EUCLID_5: 9

          .= (a * 1) by EUCLID_5: 2

          .= a;

          hence (v `3 ) <> 0 by A1;

        end;

        hence thesis;

      end;

    end

    definition

      let P be non point_at_infty Point of ( ProjectiveSpace ( TOP-REAL 3));

      :: BKMODEL4:def5

      func RP3_to_REAL2 P -> Element of ( REAL 2) means

      : Def05: ex u be non zero Element of ( TOP-REAL 3) st P = ( Dir u) & (u `3 ) = 1 & it = |[(u `1 ), (u `2 )]|;

      existence

      proof

        consider u be Element of ( TOP-REAL 3) such that

         A1: not u is zero and

         A2: P = ( Dir u) by ANPROJ_1: 26;

        

         A3: P is non point_at_infty;

        reconsider v = |[((u `1 ) / (u `3 )), ((u `2 ) / (u `3 )), 1]| as non zero Element of ( TOP-REAL 3);

        ((u `3 ) * v) = |[((u `3 ) * ((u `1 ) / (u `3 ))), ((u `3 ) * ((u `2 ) / (u `3 ))), ((u `3 ) * 1)]| by EUCLID_5: 8

        .= |[(u `1 ), ((u `3 ) * ((u `2 ) / (u `3 ))), (u `3 )]| by A1, A2, A3, XCMPLX_1: 87

        .= |[(u `1 ), (u `2 ), (u `3 )]| by A1, A2, A3, XCMPLX_1: 87

        .= u by EUCLID_5: 3;

        then are_Prop (u,v) by A1, A2, A3, ANPROJ_1: 1;

        then

         A4: P = ( Dir v) by A2, A1, ANPROJ_1: 22;

        

         A5: (v `3 ) = 1 by EUCLID_5: 2;

         |[(v `1 ), (v `2 )]| is Element of ( REAL 2) by EUCLID: 22;

        hence thesis by A4, A5;

      end;

      uniqueness

      proof

        let u,v be Element of ( REAL 2) such that

         A6: ex w be non zero Element of ( TOP-REAL 3) st P = ( Dir w) & (w `3 ) = 1 & u = |[(w `1 ), (w `2 )]| and

         A7: ex w be non zero Element of ( TOP-REAL 3) st P = ( Dir w) & (w `3 ) = 1 & v = |[(w `1 ), (w `2 )]|;

        consider w1 be non zero Element of ( TOP-REAL 3) such that

         A8: P = ( Dir w1) & (w1 `3 ) = 1 & u = |[(w1 `1 ), (w1 `2 )]| by A6;

        consider w2 be non zero Element of ( TOP-REAL 3) such that

         A9: P = ( Dir w2) & (w2 `3 ) = 1 & v = |[(w2 `1 ), (w2 `2 )]| by A7;

         are_Prop (w1,w2) by A8, A9, ANPROJ_1: 22;

        then

        consider a be Real such that a <> 0 and

         A10: w1 = (a * w2) by ANPROJ_1: 1;

        1 = (a * (w2 `3 )) by A8, A10, EUCLID_5: 9

        .= a by A9;

        

        then w1 = |[(1 * (w2 `1 )), (1 * (w2 `2 )), (1 * (w2 `3 ))]| by A10, EUCLID_5: 7

        .= w2 by EUCLID_5: 3;

        hence thesis by A8, A9;

      end;

    end

    definition

      let P be non point_at_infty Point of ( ProjectiveSpace ( TOP-REAL 3));

      :: BKMODEL4:def6

      func RP3_to_T2 P -> Point of TarskiEuclid2Space equals ( RP3_to_REAL2 P);

      coherence

      proof

         the MetrStruct of TarskiEuclid2Space = the MetrStruct of ( Euclid 2) by GTARSKI1:def 13;

        hence thesis;

      end;

    end

    theorem :: BKMODEL4:48

    

     Th41: for P,Q,R,P9,Q9,R9 be non point_at_infty Element of ( ProjectiveSpace ( TOP-REAL 3)) holds for h be Element of SubGroupK-isometry holds for N be invertible Matrix of 3, F_Real st h = ( homography N) & P in BK_model & Q in BK_model & R in absolute & P9 = (( homography N) . P) & Q9 = (( homography N) . Q) & R9 = (( homography N) . R) & between (( RP3_to_T2 P),( RP3_to_T2 Q),( RP3_to_T2 R)) holds between (( RP3_to_T2 P9),( RP3_to_T2 Q9),( RP3_to_T2 R9))

    proof

      let P,Q,R,P9,Q9,R9 be non point_at_infty Element of ( ProjectiveSpace ( TOP-REAL 3));

      let h be Element of SubGroupK-isometry ;

      let N be invertible Matrix of 3, F_Real ;

      assume that

       A1: h = ( homography N) and

       A2: P in BK_model and

       A3: Q in BK_model and

       A4: R in absolute and

       A5: P9 = (( homography N) . P) and

       A6: Q9 = (( homography N) . Q) and

       A7: R9 = (( homography N) . R) and

       A8: between (( RP3_to_T2 P),( RP3_to_T2 Q),( RP3_to_T2 R));

      consider n11,n12,n13,n21,n22,n23,n31,n32,n33 be Element of F_Real such that

       A9: N = <* <*n11, n12, n13*>, <*n21, n22, n23*>, <*n31, n32, n33*>*> by PASCAL: 3;

      consider u be non zero Element of ( TOP-REAL 3) such that

       A10: P = ( Dir u) & (u `3 ) = 1 & ( RP3_to_REAL2 P) = |[(u `1 ), (u `2 )]| by Def05;

      

       A11: |[(u `1 ), (u `2 )]| = |[(u . 1), (u `2 )]| by EUCLID_5:def 1

      .= |[(u . 1), (u . 2)]| by EUCLID_5:def 2;

      then

       A12: P = ( Dir u) & (u . 3) = 1 & ( RP3_to_REAL2 P) = |[(u . 1), (u . 2)]| by A10, EUCLID_5:def 3;

      consider v be non zero Element of ( TOP-REAL 3) such that

       A13: R = ( Dir v) & (v `3 ) = 1 & ( RP3_to_REAL2 R) = |[(v `1 ), (v `2 )]| by Def05;

      

       A14: |[(v `1 ), (v `2 )]| = |[(v . 1), (v `2 )]| by EUCLID_5:def 1

      .= |[(v . 1), (v . 2)]| by EUCLID_5:def 2;

      then

       A15: R = ( Dir v) & (v . 3) = 1 & ( RP3_to_REAL2 R) = |[(v . 1), (v . 2)]| by A13, EUCLID_5:def 3;

      consider w be non zero Element of ( TOP-REAL 3) such that

       A16: Q = ( Dir w) & (w `3 ) = 1 & ( RP3_to_REAL2 Q) = |[(w `1 ), (w `2 )]| by Def05;

      

       A17: |[(w `1 ), (w `2 )]| = |[(w . 1), (w `2 )]| by EUCLID_5:def 1

      .= |[(w . 1), (w . 2)]| by EUCLID_5:def 2;

      then

       A18: Q = ( Dir w) & (w . 3) = 1 & ( RP3_to_REAL2 Q) = |[(w . 1), (w . 2)]| by A16, EUCLID_5:def 3;

      reconsider nu1 = (((n11 * (u . 1)) + (n12 * (u . 2))) + n13), nu2 = (((n21 * (u . 1)) + (n22 * (u . 2))) + n23), nu3 = (((n31 * (u . 1)) + (n32 * (u . 2))) + n33), nv1 = (((n11 * (v . 1)) + (n12 * (v . 2))) + n13), nv2 = (((n21 * (v . 1)) + (n22 * (v . 2))) + n23), nv3 = (((n31 * (v . 1)) + (n32 * (v . 2))) + n33), nw1 = (((n11 * (w . 1)) + (n12 * (w . 2))) + n13), nw2 = (((n21 * (w . 1)) + (n22 * (w . 2))) + n23), nw3 = (((n31 * (w . 1)) + (n32 * (w . 2))) + n33) as Real;

      ( Tn2TR ( RP3_to_T2 Q)) in ( LSeg (( Tn2TR ( RP3_to_T2 P)),( Tn2TR ( RP3_to_T2 R)))) by A8, GTARSKI2: 20;

      then

      consider l be Real such that

       A19: 0 <= l & l <= 1 and

       A20: ( Tn2TR ( RP3_to_T2 Q)) = (((1 - l) * ( Tn2TR ( RP3_to_T2 P))) + (l * ( Tn2TR ( RP3_to_T2 R)))) by RLTOPSP1: 76;

       |[(w . 1), (w . 2)]| = ( |[((1 - l) * (u . 1)), ((1 - l) * (u . 2))]| + (l * |[(v . 1), (v . 2)]|)) by A20, A11, A10, A14, A17, A16, A13, EUCLID: 58

      .= ( |[((1 - l) * (u . 1)), ((1 - l) * (u . 2))]| + |[(l * (v . 1)), (l * (v . 2))]|) by EUCLID: 58

      .= |[(((1 - l) * (u . 1)) + (l * (v . 1))), (((1 - l) * (u . 2)) + (l * (v . 2)))]| by EUCLID: 56;

      then

       A21: (w . 1) = (((1 - l) * (u . 1)) + (l * (v . 1))) & (w . 2) = (((1 - l) * (u . 2)) + (l * (v . 2))) by FINSEQ_1: 77;

      set r = ((l * nv3) / (((1 - l) * nu3) + (l * nv3)));

      now

        

        thus w = |[(w `1 ), (w `2 ), (w `3 )]| by EUCLID_5: 3

        .= |[(w . 1), (w `2 ), (w `3 )]| by EUCLID_5:def 1

        .= |[(((1 - l) * (u . 1)) + (l * (v . 1))), (((1 - l) * (u . 2)) + (l * (v . 2))), (((1 - l) * 1) + (l * 1))]| by A16, A21, EUCLID_5:def 2

        .= ( |[((1 - l) * (u . 1)), ((1 - l) * (u . 2)), ((1 - l) * 1)]| + |[(l * (v . 1)), (l * (v . 2)), (l * 1)]|) by EUCLID_5: 6

        .= (((1 - l) * |[(u . 1), (u . 2), 1]|) + |[(l * (v . 1)), (l * (v . 2)), (l * 1)]|) by EUCLID_5: 8

        .= (((1 - l) * |[(u . 1), (u . 2), 1]|) + (l * |[(v . 1), (v . 2), 1]|)) by EUCLID_5: 8

        .= (((1 - l) * u) + (l * |[(v . 1), (v . 2), (v . 3)]|)) by A12, A15, Th35

        .= (((1 - l) * u) + (l * v)) by Th35;

        thus nu3 <> 0 by A1, A2, A9, A12, Th20;

        thus nv3 <> 0 by A1, A4, A9, A15, Th22;

        thus

         A22: nw3 <> 0 by A3, A1, A9, A18, Th20;

        thus nw3 = (((1 - l) * nu3) + (l * nv3)) by A21;

        thus (((1 - l) * nu3) + (l * nv3)) <> 0 by A22, A21;

      end;

      then

       A23: (((1 - r) * |[(nu1 / nu3), (nu2 / nu3), 1]|) + (r * |[(nv1 / nv3), (nv2 / nv3), 1]|)) = |[(nw1 / nw3), (nw2 / nw3), 1]| by Th34;

      

       A24: 0 <= r <= 1

      proof

        now

          thus 0 <= l <= 1 by A19;

          thus 0 < (nu3 * nv3)

          proof

            reconsider u1 = |[(u . 1), (u . 2)]|, v1 = |[(v . 1), (v . 2)]| as Element of ( TOP-REAL 2);

            

             A25: (u1 . 1) = (u1 `1 )

            .= (u . 1) by EUCLID: 52;

            

             A26: (u1 . 2) = (u1 `2 )

            .= (u . 2) by EUCLID: 52;

            

             A27: (v1 . 1) = (v1 `1 )

            .= (v . 1) by EUCLID: 52;

            

             A28: (v1 . 2) = (v1 `2 )

            .= (v . 2) by EUCLID: 52;

            reconsider m31 = n31, m32 = n32, m33 = n33 as Element of F_Real ;

            now

              reconsider PP = P as Element of BK_model by A2;

              consider u3 be non zero Element of ( TOP-REAL 3) such that

               A29: ( Dir u3) = PP & (u3 . 3) = 1 & ( BK_to_REAL2 PP) = |[(u3 . 1), (u3 . 2)]| by BKMODEL2:def 2;

              u3 = u by A12, A29, Th16;

              hence u1 in ( inside_of_circle ( 0 , 0 ,1)) by A29;

              thus v1 in ( circle ( 0 , 0 ,1)) by A4, A15, BKMODEL1: 84;

              thus for w1 be Element of ( TOP-REAL 2) st w1 in ( closed_inside_of_circle ( 0 , 0 ,1)) holds (((m31 * (w1 . 1)) + (m32 * (w1 . 2))) + m33) <> 0 by A1, A9, Th38;

            end;

            hence thesis by A25, A26, A27, A28, Th30;

          end;

        end;

        hence thesis by Th31;

      end;

      now

        thus 0 <= r <= 1 by A24;

        thus ( Tn2TR ( RP3_to_T2 Q9)) = (((1 - r) * ( Tn2TR ( RP3_to_T2 P9))) + (r * ( Tn2TR ( RP3_to_T2 R9))))

        proof

          reconsider u2 = |[(nu1 / nu3), (nu2 / nu3), 1]| as non zero Element of ( TOP-REAL 3);

          reconsider PP9 = P9 as non point_at_infty Point of ( ProjectiveSpace ( TOP-REAL 3));

          consider u3 be non zero Element of ( TOP-REAL 3) such that

           A30: PP9 = ( Dir u3) & (u3 `3 ) = 1 & ( RP3_to_REAL2 PP9) = |[(u3 `1 ), (u3 `2 )]| by Def05;

          now

            thus ( Dir u3) = ( Dir u2) by A1, A2, A9, A12, Th23, A5, A30;

            

            thus (u2 . 3) = (u2 `3 ) by EUCLID_5:def 3

            .= 1 by EUCLID_5: 2;

            hence (u2 . 3) = (u3 . 3) by A30, EUCLID_5:def 3;

          end;

          then u2 = u3 by BKMODEL1: 43;

          

          then

           A31: ( RP3_to_REAL2 P9) = |[(nu1 / nu3), (u2 `2 )]| by A30, EUCLID_5: 2

          .= |[(nu1 / nu3), (nu2 / nu3)]| by EUCLID_5: 2;

          reconsider v2 = |[(nv1 / nv3), (nv2 / nv3), 1]| as non zero Element of ( TOP-REAL 3);

          consider v3 be non zero Element of ( TOP-REAL 3) such that

           A32: ( Dir v3) = R9 & (v3 `3 ) = 1 & ( RP3_to_REAL2 R9) = |[(v3 `1 ), (v3 `2 )]| by Def05;

          now

            thus ( Dir v3) = ( Dir v2) by A15, A1, A4, A9, Th24, A7, A32;

            

            thus (v2 . 3) = (v2 `3 ) by EUCLID_5:def 3

            .= 1 by EUCLID_5: 2;

            hence (v2 . 3) = (v3 . 3) by A32, EUCLID_5:def 3;

          end;

          then v2 = v3 by BKMODEL1: 43;

          

          then

           A33: ( RP3_to_REAL2 R9) = |[(nv1 / nv3), (v2 `2 )]| by A32, EUCLID_5: 2

          .= |[(nv1 / nv3), (nv2 / nv3)]| by EUCLID_5: 2;

          reconsider w2 = |[(nw1 / nw3), (nw2 / nw3), 1]| as non zero Element of ( TOP-REAL 3);

          consider w3 be non zero Element of ( TOP-REAL 3) such that

           A34: ( Dir w3) = Q9 & (w3 `3 ) = 1 & ( RP3_to_REAL2 Q9) = |[(w3 `1 ), (w3 `2 )]| by Def05;

          now

            thus ( Dir w3) = ( Dir w2) by A3, A1, A9, A18, Th23, A6, A34;

            

            thus (w2 . 3) = (w2 `3 ) by EUCLID_5:def 3

            .= 1 by EUCLID_5: 2;

            hence (w2 . 3) = (w3 . 3) by A34, EUCLID_5:def 3;

          end;

          then w2 = w3 by BKMODEL1: 43;

          

          then

           A35: ( RP3_to_REAL2 Q9) = |[(nw1 / nw3), (w2 `2 )]| by A34, EUCLID_5: 2

          .= |[(nw1 / nw3), (nw2 / nw3)]| by EUCLID_5: 2;

          ( RP3_to_REAL2 Q9) = (((1 - r) * ( RP3_to_REAL2 P9)) + (r * ( RP3_to_REAL2 R9)))

          proof

            reconsider a = (nu1 / nu3), b = (nu2 / nu3), c = (nv1 / nv3), d = (nv2 / nv3), e = (nw1 / nw3), f = (nw2 / nw3) as Real;

            (((1 - r) * |[a, b]|) + (r * |[c, d]|)) = |[e, f]| by Th39, A23;

            hence thesis by A31, A33, A35;

          end;

          hence thesis;

        end;

      end;

      then ( Tn2TR ( RP3_to_T2 Q9)) in { (((1 - r) * ( Tn2TR ( RP3_to_T2 P9))) + (r * ( Tn2TR ( RP3_to_T2 R9)))) where r be Real : 0 <= r & r <= 1 };

      then ( Tn2TR ( RP3_to_T2 Q9)) in ( LSeg (( Tn2TR ( RP3_to_T2 P9)),( Tn2TR ( RP3_to_T2 R9)))) by RLTOPSP1:def 2;

      hence thesis by GTARSKI2: 20;

    end;

    theorem :: BKMODEL4:49

    

     Th42: for a,b,c be Real holds for u,v,w be Element of ( TOP-REAL 3) st a <> 0 & ((a + b) + c) = 0 & (((a * u) + (b * v)) + (c * w)) = ( 0. ( TOP-REAL 3)) holds u in ( Line (v,w))

    proof

      let a,b,c be Real;

      let u,v,w be Element of ( TOP-REAL 3);

      assume that

       A1: a <> 0 and

       A2: ((a + b) + c) = 0 and

       A3: (((a * u) + (b * v)) + (c * w)) = ( 0. ( TOP-REAL 3));

      

       A4: u = (((( - b) / a) * v) + ((( - c) / a) * w)) by A1, A3, ANPROJ_8: 12;

      reconsider r = (( - c) / a) as Real;

      (1 - r) = ((a / a) + (c / a)) by A1, XCMPLX_1: 60

      .= ((a + c) / a)

      .= (( - b) / a) by A2;

      then u in the set of all (((1 - r) * v) + (r * w)) where r be Real by A4;

      hence thesis by RLTOPSP1:def 14;

    end;

    theorem :: BKMODEL4:50

    

     Th43: for P,Q,R be non point_at_infty Point of ( ProjectiveSpace ( TOP-REAL 3)) holds for u,v,w be non zero Element of ( TOP-REAL 3) st P = ( Dir u) & Q = ( Dir v) & R = ( Dir w) & (u `3 ) = 1 & (v `3 ) = 1 & (w `3 ) = 1 holds (P,Q,R) are_collinear iff (u,v,w) are_collinear

    proof

      let P,Q,R be non point_at_infty Point of ( ProjectiveSpace ( TOP-REAL 3));

      let u,v,w be non zero Element of ( TOP-REAL 3);

      assume that

       A1: P = ( Dir u) & Q = ( Dir v) & R = ( Dir w) and

       A2: (u `3 ) = 1 & (v `3 ) = 1 & (w `3 ) = 1;

      reconsider i = 3 as Nat;

      hereby

        assume (P,Q,R) are_collinear ;

        then

        consider u9,v9,w9 be Element of ( TOP-REAL 3) such that

         A3: P = ( Dir u9) & Q = ( Dir v9) & R = ( Dir w9) & not u9 is zero & not v9 is zero & not w9 is zero and

         A4: ex a,b,c be Real st (((a * u9) + (b * v9)) + (c * w9)) = ( 0. ( TOP-REAL 3)) & (a <> 0 or b <> 0 or c <> 0 ) by ANPROJ_8: 11;

        

         A5: |{u9, v9, w9}| = 0 by A4, ANPROJ_8: 41;

         are_Prop (u,u9) by A1, A3, ANPROJ_1: 22;

        then

        consider a be Real such that

         A6: a <> 0 and

         A7: u9 = (a * u) by ANPROJ_1: 1;

         are_Prop (v,v9) by A1, A3, ANPROJ_1: 22;

        then

        consider b be Real such that

         A8: b <> 0 and

         A9: v9 = (b * v) by ANPROJ_1: 1;

         are_Prop (w,w9) by A1, A3, ANPROJ_1: 22;

        then

        consider c be Real such that

         A10: c <> 0 and

         A11: w9 = (c * w) by ANPROJ_1: 1;

        reconsider d = (a * (b * c)) as non zero Real by A6, A8, A10;

         0 = (a * |{u, (b * v), (c * w)}|) by ANPROJ_8: 31, A5, A7, A9, A11

        .= (a * (b * |{u, v, (c * w)}|)) by ANPROJ_8: 32

        .= (a * (b * (c * |{u, v, w}|))) by ANPROJ_8: 33

        .= (d * |{u, v, w}|);

        then |{u, v, w}| = 0 ;

        then

        consider a,b,c be Real such that

         A12: (((a * u) + (b * v)) + (c * w)) = ( 0. ( TOP-REAL 3)) and

         A13: a <> 0 or b <> 0 or c <> 0 by ANPROJ_8: 43, ANPROJ_1:def 2;

        reconsider aubv = ((a * u) + (b * v)), cw = (c * w), au = (a * u), bv = (b * v) as Element of ( TOP-REAL 3);

        

         A14: cw is Element of ( REAL 3) by EUCLID: 22;

        

         A15: aubv is Element of ( REAL 3) by EUCLID: 22;

        au is Element of ( REAL 3) & bv is Element of ( REAL 3) by EUCLID: 22;

        

        then

         A16: (aubv . 3) = ((au . 3) + (bv . 3)) by RVSUM_1: 11

        .= ((a * (u . 3)) + (bv . 3)) by RVSUM_1: 44

        .= ((a * (u . 3)) + (b * (v . 3))) by RVSUM_1: 44;

        

         A17: (cw . 3) = (c * (w . 3)) by RVSUM_1: 44;

         |[((aubv + cw) `1 ), ((aubv + cw) `2 ), ((aubv + cw) `3 )]| = |[ 0 , 0 , 0 ]| by A12, EUCLID_5: 3, EUCLID_5: 4;

        

        then

         A18: 0 = ((aubv + cw) `3 ) by FINSEQ_1: 78

        .= ((aubv + cw) . 3) by EUCLID_5:def 3

        .= ((aubv . 3) + (cw . 3)) by A14, A15, RVSUM_1: 11

        .= (((a * (u `3 )) + (b * (v . 3))) + (c * (w . 3))) by A16, A17, EUCLID_5:def 3

        .= (((a * (u `3 )) + (b * (v `3 ))) + (c * (w . 3))) by EUCLID_5:def 3

        .= (((a * (u `3 )) + (b * (v `3 ))) + (c * (w `3 ))) by EUCLID_5:def 3

        .= ((a + b) + c) by A2;

        thus (u,v,w) are_collinear

        proof

          per cases by A13;

            suppose

             A19: a <> 0 ;

            reconsider L = ( Line (v,w)) as line of ( TOP-REAL 3);

            u in L & v in L & w in L by A18, A12, Th42, A19, RLTOPSP1: 72;

            hence thesis by RLTOPSP1:def 16;

          end;

            suppose

             A20: b <> 0 ;

            

             A21: (((b * v) + (c * w)) + (a * u)) = ( 0. ( TOP-REAL 3)) by A12, RVSUM_1: 15;

            

             A22: ((b + c) + a) = 0 by A18;

            reconsider L = ( Line (w,u)) as line of ( TOP-REAL 3);

            v in L & w in L & u in L by A22, A20, A21, Th42, RLTOPSP1: 72;

            hence thesis by RLTOPSP1:def 16;

          end;

            suppose

             A23: c <> 0 ;

            

             A24: (((c * w) + (a * u)) + (b * v)) = ( 0. ( TOP-REAL 3)) by A12, RVSUM_1: 15;

            

             A25: ((c + a) + b) = 0 by A18;

            reconsider L = ( Line (u,v)) as line of ( TOP-REAL 3);

            w in L & u in L & v in L by A25, A23, A24, Th42, RLTOPSP1: 72;

            hence thesis by RLTOPSP1:def 16;

          end;

        end;

      end;

      assume (u,v,w) are_collinear ;

      per cases by TOPREAL9: 67;

        suppose u in ( LSeg (v,w));

        then

        consider r be Real such that 0 <= r & r <= 1 and

         A26: u = (((1 - r) * v) + (r * w)) by RLTOPSP1: 76;

        reconsider a = 1, b = (r - 1), c = ( - r) as Real;

        (((1 * u) + ((r - 1) * v)) + (( - r) * w)) = ( 0. ( TOP-REAL 3))

        proof

          reconsider vw = (v + w) as Element of ( REAL 3) by EUCLID: 22;

          (1 * u) = (((1 - r) * v) + (r * w)) by A26, RVSUM_1: 52;

          

          then (((1 * u) + ((r - 1) * v)) + (( - r) * w)) = (((r * w) + (((1 - r) * v) + ((r - 1) * v))) + (( - r) * w)) by RVSUM_1: 15

          .= (((r * w) + (((1 - r) + (r - 1)) * v)) + (( - r) * w)) by RVSUM_1: 50

          .= (( 0 * v) + ((r * w) + (( - r) * w))) by RVSUM_1: 15

          .= (( 0 * v) + ((r + ( - r)) * w)) by RVSUM_1: 50

          .= ( 0 * vw) by RVSUM_1: 51

          .= (i |-> 0 ) by RVSUM_1: 53

          .= ( 0. ( TOP-REAL 3)) by EUCLID_5: 4, FINSEQ_2: 62;

          hence thesis;

        end;

        hence thesis by A1, ANPROJ_8: 11;

      end;

        suppose v in ( LSeg (w,u));

        then

        consider r be Real such that 0 <= r & r <= 1 and

         A27: v = (((1 - r) * w) + (r * u)) by RLTOPSP1: 76;

        reconsider a = ( - r), b = 1, c = (r - 1) as Real;

        (((( - r) * u) + (1 * v)) + ((r - 1) * w)) = ( 0. ( TOP-REAL 3))

        proof

          reconsider uw = (u + w) as Element of ( REAL 3) by EUCLID: 22;

          (1 * v) = (((1 - r) * w) + (r * u)) by A27, RVSUM_1: 52;

          

          then (((( - r) * u) + (1 * v)) + ((r - 1) * w)) = ((((( - r) * u) + (r * u)) + ((1 - r) * w)) + ((r - 1) * w)) by RVSUM_1: 15

          .= ((((( - r) + r) * u) + ((1 - r) * w)) + ((r - 1) * w)) by RVSUM_1: 50

          .= (( 0 * u) + (((1 - r) * w) + ((r - 1) * w))) by RVSUM_1: 15

          .= (( 0 * u) + (((1 - r) + (r - 1)) * w)) by RVSUM_1: 50

          .= ( 0 * uw) by RVSUM_1: 51

          .= (i |-> 0 ) by RVSUM_1: 53

          .= ( 0. ( TOP-REAL 3)) by FINSEQ_2: 62, EUCLID_5: 4;

          hence thesis;

        end;

        hence thesis by A1, ANPROJ_8: 11;

      end;

        suppose w in ( LSeg (u,v));

        then

        consider r be Real such that 0 <= r & r <= 1 and

         A28: w = (((1 - r) * u) + (r * v)) by RLTOPSP1: 76;

        reconsider a = (r - 1), b = ( - r), c = 1 as Real;

        ((((r - 1) * u) + (( - r) * v)) + (1 * w)) = ( 0. ( TOP-REAL 3))

        proof

          reconsider vu = (v + u) as Element of ( REAL 3) by EUCLID: 22;

          (1 * w) = (((1 - r) * u) + (r * v)) by A28, RVSUM_1: 52;

          

          then ((((r - 1) * u) + (( - r) * v)) + (1 * w)) = (((r - 1) * u) + ((( - r) * v) + ((r * v) + ((1 - r) * u)))) by RVSUM_1: 15

          .= (((r - 1) * u) + (((( - r) * v) + (r * v)) + ((1 - r) * u))) by RVSUM_1: 15

          .= (((r - 1) * u) + (((( - r) + r) * v) + ((1 - r) * u))) by RVSUM_1: 50

          .= (( 0 * v) + (((r - 1) * u) + ((1 - r) * u))) by RVSUM_1: 15

          .= (( 0 * v) + (((r - 1) + (1 - r)) * u)) by RVSUM_1: 50

          .= ( 0 * vu) by RVSUM_1: 51

          .= (i |-> 0 ) by RVSUM_1: 53

          .= ( 0. ( TOP-REAL 3)) by FINSEQ_2: 62, EUCLID_5: 4;

          hence thesis;

        end;

        hence thesis by A1, ANPROJ_8: 11;

      end;

    end;

    theorem :: BKMODEL4:51

    

     Th44: for u,v,w be Element of ( TOP-REAL 3) st u in ( LSeg (v,w)) holds |[(u `1 ), (u `2 )]| in ( LSeg ( |[(v `1 ), (v `2 )]|, |[(w `1 ), (w `2 )]|))

    proof

      let u,v,w be Element of ( TOP-REAL 3);

      assume u in ( LSeg (v,w));

      then

      consider r be Real such that

       A1: 0 <= r and

       A2: r <= 1 and

       A3: u = (((1 - r) * v) + (r * w)) by RLTOPSP1: 76;

      reconsider rv = ((1 - r) * v), rw = (r * w) as Element of ( TOP-REAL 3);

      rv = |[((1 - r) * (v `1 )), ((1 - r) * (v `2 )), ((1 - r) * (v `3 ))]| & rw = |[(r * (w `1 )), (r * (w `2 )), (r * (w `3 ))]| by EUCLID_5: 7;

      

      then |[(((1 - r) * (v `1 )) + (r * (w `1 ))), (((1 - r) * (v `2 )) + (r * (w `2 ))), (((1 - r) * (v `3 )) + (r * (w `3 )))]| = u by A3, EUCLID_5: 6

      .= |[(u `1 ), (u `2 ), (u `3 )]| by EUCLID_5: 3;

      then

       A4: (u `1 ) = (((1 - r) * (v `1 )) + (r * (w `1 ))) & (u `2 ) = (((1 - r) * (v `2 )) + (r * (w `2 ))) by FINSEQ_1: 78;

      reconsider u9 = |[(u `1 ), (u `2 )]|, v9 = |[(v `1 ), (v `2 )]|, w9 = |[(w `1 ), (w `2 )]| as Element of ( TOP-REAL 2);

      

       A5: (u9 `1 ) = (u `1 ) & (u9 `2 ) = (u `2 ) & (v9 `1 ) = (v `1 ) & (v9 `2 ) = (v `2 ) & (w9 `1 ) = (w `1 ) & (w9 `2 ) = (w `2 ) by EUCLID: 52;

      reconsider rv9 = ((1 - r) * v9), rw9 = (r * w9) as Element of ( TOP-REAL 2);

      rv9 = |[((1 - r) * (v9 `1 )), ((1 - r) * (v9 `2 ))]| & rw9 = |[(r * (w9 `1 )), (r * (w9 `2 ))]| by EUCLID: 57;

      then (rv9 + rw9) = |[(u `1 ), (u `2 )]| by A4, A5, EUCLID: 56;

      then u9 in { (((1 - r) * v9) + (r * w9)) where r be Real : 0 <= r & r <= 1 } by A1, A2;

      hence thesis by RLTOPSP1:def 2;

    end;

    theorem :: BKMODEL4:52

    

     Th45: for u,v,w be Element of ( TOP-REAL 2) st u in ( LSeg (v,w)) holds |[(u `1 ), (u `2 ), 1]| in ( LSeg ( |[(v `1 ), (v `2 ), 1]|, |[(w `1 ), (w `2 ), 1]|))

    proof

      let u,v,w be Element of ( TOP-REAL 2);

      assume u in ( LSeg (v,w));

      then

      consider r be Real such that

       A1: 0 <= r and

       A2: r <= 1 and

       A3: u = (((1 - r) * v) + (r * w)) by RLTOPSP1: 76;

      reconsider u9 = |[(u `1 ), (u `2 ), 1]|, v9 = |[(v `1 ), (v `2 ), 1]|, w9 = |[(w `1 ), (w `2 ), 1]| as Element of ( TOP-REAL 3);

      reconsider rv = ((1 - r) * v), rw = (r * w) as Element of ( REAL 2) by EUCLID: 22;

      

       A4: (rv . 1) = ((1 - r) * (v . 1)) & (rv . 2) = ((1 - r) * (v . 2)) & (rw . 1) = (r * (w . 1)) & (rw . 2) = (r * (w . 2)) by RVSUM_1: 44;

      

       A5: (u `2 ) = (((1 - r) * (v . 2)) + (r * (w . 2))) by A4, A3, RVSUM_1: 11;

      reconsider rv9 = ((1 - r) * v9), rw9 = (r * w9) as Element of ( TOP-REAL 3);

      u9 = (((1 - r) * v9) + (r * w9))

      proof

        u9 = |[(((1 - r) * (v . 1)) + (r * (w . 1))), (((1 - r) * (v . 2)) + (r * (w . 2))), (((1 - r) * 1) + (r * 1))]| by A5, A3, A4, RVSUM_1: 11

        .= ( |[((1 - r) * (v . 1)), ((1 - r) * (v . 2)), ((1 - r) * 1)]| + |[(r * (w . 1)), (r * (w . 2)), (r * 1)]|) by EUCLID_5: 6

        .= (((1 - r) * |[(v . 1), (v . 2), 1]|) + |[(r * (w . 1)), (r * (w . 2)), (r * 1)]|) by EUCLID_5: 8

        .= (((1 - r) * |[(v `1 ), (v `2 ), 1]|) + (r * |[(w `1 ), (w `2 ), 1]|)) by EUCLID_5: 8;

        hence thesis;

      end;

      then u9 in { (((1 - r) * v9) + (r * w9)) where r be Real : 0 <= r & r <= 1 } by A1, A2;

      hence thesis by RLTOPSP1:def 2;

    end;

    theorem :: BKMODEL4:53

    

     Th46: for P,Q,R be non point_at_infty Point of ( ProjectiveSpace ( TOP-REAL 3)) holds (P,Q,R) are_collinear iff Collinear (( RP3_to_T2 P),( RP3_to_T2 Q),( RP3_to_T2 R))

    proof

      let P,Q,R be non point_at_infty Point of ( ProjectiveSpace ( TOP-REAL 3));

      reconsider p = ( RP3_to_T2 P), q = ( RP3_to_T2 Q), r = ( RP3_to_T2 R) as POINT of TarskiEuclid2Space ;

      consider u be non zero Element of ( TOP-REAL 3) such that

       A1: P = ( Dir u) & (u `3 ) = 1 & ( RP3_to_REAL2 P) = |[(u `1 ), (u `2 )]| by Def05;

      consider v be non zero Element of ( TOP-REAL 3) such that

       A2: Q = ( Dir v) & (v `3 ) = 1 & ( RP3_to_REAL2 Q) = |[(v `1 ), (v `2 )]| by Def05;

      consider w be non zero Element of ( TOP-REAL 3) such that

       A3: R = ( Dir w) & (w `3 ) = 1 & ( RP3_to_REAL2 R) = |[(w `1 ), (w `2 )]| by Def05;

      hereby

        assume

         A4: (P,Q,R) are_collinear ;

        (u,v,w) are_collinear by A4, A1, A2, A3, Th43;

        per cases by TOPREAL9: 67;

          suppose u in ( LSeg (v,w));

          then ( Tn2TR p) in ( LSeg (( Tn2TR q),( Tn2TR r))) by A1, A2, A3, Th44;

          hence Collinear (( RP3_to_T2 P),( RP3_to_T2 Q),( RP3_to_T2 R)) by GTARSKI2: 20;

        end;

          suppose v in ( LSeg (w,u));

          then ( Tn2TR q) in ( LSeg (( Tn2TR r),( Tn2TR p))) by A1, A2, A3, Th44;

          hence Collinear (( RP3_to_T2 P),( RP3_to_T2 Q),( RP3_to_T2 R)) by GTARSKI2: 20;

        end;

          suppose w in ( LSeg (u,v));

          then ( Tn2TR r) in ( LSeg (( Tn2TR p),( Tn2TR q))) by A1, A2, A3, Th44;

          hence Collinear (( RP3_to_T2 P),( RP3_to_T2 Q),( RP3_to_T2 R)) by GTARSKI2: 20;

        end;

      end;

      assume Collinear (( RP3_to_T2 P),( RP3_to_T2 Q),( RP3_to_T2 R));

      then

       A5: ( Tn2TR q) in ( LSeg (( Tn2TR p),( Tn2TR r))) or ( Tn2TR r) in ( LSeg (( Tn2TR q),( Tn2TR p))) or ( Tn2TR p) in ( LSeg (( Tn2TR r),( Tn2TR q))) by GTARSKI2: 20;

      reconsider u1 = ( Tn2TR p), v1 = ( Tn2TR q), w1 = ( Tn2TR r) as Element of ( TOP-REAL 2);

      reconsider u9 = |[(u1 `1 ), (u1 `2 ), 1]|, v9 = |[(v1 `1 ), (v1 `2 ), 1]|, w9 = |[(w1 `1 ), (w1 `2 ), 1]| as Element of ( TOP-REAL 3);

      now

        (u1 `1 ) = (u `1 ) & (u1 `2 ) = (u `2 ) & (v1 `1 ) = (v `1 ) & (v1 `2 ) = (v `2 ) & (w1 `1 ) = (w `1 ) & (w1 `2 ) = (w `2 ) by A1, A2, A3, EUCLID: 52;

        hence ( Dir u9) = P & ( Dir v9) = Q & ( Dir w9) = R by A1, A2, A3, EUCLID_5: 3;

        thus (u9 `3 ) = 1 & (v9 `3 ) = 1 & (w9 `3 ) = 1 by EUCLID_5: 2;

        v9 in ( LSeg (u9,w9)) or w9 in ( LSeg (v9,u9)) or u9 in ( LSeg (w9,v9)) by A5, Th45;

        hence (u9,v9,w9) are_collinear by TOPREAL9: 67;

      end;

      hence (P,Q,R) are_collinear by Th43;

    end;

    theorem :: BKMODEL4:54

    for u,v,w be Element of ( TOP-REAL 2) st (u,v,w) are_collinear holds ( |[(u `1 ), (u `2 ), 1]|, |[(v `1 ), (v `2 ), 1]|, |[(w `1 ), (w `2 ), 1]|) are_collinear

    proof

      let u,v,w be Element of ( TOP-REAL 2);

      assume

       A1: (u,v,w) are_collinear ;

      reconsider u1 = |[(u `1 ), (u `2 ), 1]|, v1 = |[(v `1 ), (v `2 ), 1]|, w1 = |[(w `1 ), (w `2 ), 1]| as non zero Point of ( TOP-REAL 3);

      u in ( LSeg (v,w)) or v in ( LSeg (w,u)) or w in ( LSeg (u,v)) by A1, TOPREAL9: 67;

      then u1 in ( LSeg (v1,w1)) or v1 in ( LSeg (w1,u1)) or w1 in ( LSeg (u1,v1)) by Th45;

      hence thesis by TOPREAL9: 67;

    end;

    theorem :: BKMODEL4:55

    

     Th47: for P,Q,P1 be non point_at_infty Element of ( ProjectiveSpace ( TOP-REAL 3)) st P in BK_model & Q in BK_model & P1 in absolute holds not between (( RP3_to_T2 Q),( RP3_to_T2 P1),( RP3_to_T2 P))

    proof

      let P,Q,P1 be non point_at_infty Element of ( ProjectiveSpace ( TOP-REAL 3));

      assume

       A1: P in BK_model & Q in BK_model & P1 in absolute ;

      set P9 = ( RP3_to_T2 P), Q9 = ( RP3_to_T2 Q), P19 = ( RP3_to_T2 P1);

      assume

       A2: between (Q9,P19,P9);

      consider u be non zero Element of ( TOP-REAL 3) such that

       A3: P = ( Dir u) & (u `3 ) = 1 & ( RP3_to_REAL2 P) = |[(u `1 ), (u `2 )]| by Def05;

      consider v be non zero Element of ( TOP-REAL 3) such that

       A4: Q = ( Dir v) & (v `3 ) = 1 & ( RP3_to_REAL2 Q) = |[(v `1 ), (v `2 )]| by Def05;

      consider w1 be non zero Element of ( TOP-REAL 3) such that

       A5: P1 = ( Dir w1) & (w1 `3 ) = 1 & ( RP3_to_REAL2 P1) = |[(w1 `1 ), (w1 `2 )]| by Def05;

      

       A6: ( Tn2TR P19) in ( LSeg (( Tn2TR Q9),( Tn2TR P9))) by A2, GTARSKI2: 20;

      reconsider u9 = ( Tn2TR P19), v9 = ( Tn2TR Q9), w9 = ( Tn2TR P9) as Element of ( TOP-REAL 2);

       |[(u9 `1 ), (u9 `2 )]| = |[(w1 `1 ), (w1 `2 )]| by A5, EUCLID: 53;

      then

       A7: (u9 `1 ) = (w1 `1 ) & (u9 `2 ) = (w1 `2 ) by FINSEQ_1: 77;

       |[(v9 `1 ), (v9 `2 )]| = |[(v `1 ), (v `2 )]| by A4, EUCLID: 53;

      then

       A8: (v9 `1 ) = (v `1 ) & (v9 `2 ) = (v `2 ) by FINSEQ_1: 77;

       |[(w9 `1 ), (w9 `2 )]| = |[(u `1 ), (u `2 )]| by A3, EUCLID: 53;

      then

       A9: (w9 `1 ) = (u `1 ) & (w9 `2 ) = (u `2 ) by FINSEQ_1: 77;

      reconsider pu = |[(u9 `1 ), (u9 `2 ), 1]|, pv = |[(v9 `1 ), (v9 `2 ), 1]|, pw = |[(w9 `1 ), (w9 `2 ), 1]| as non zero Element of ( TOP-REAL 3);

      pu in ( LSeg (pw,pv)) by A6, Th45;

      then

      consider r be Real such that

       A10: 0 <= r & r <= 1 and

       A11: pu = (((1 - r) * pw) + (r * pv)) by RLTOPSP1: 76;

      now

        thus Q = ( Dir pv) by A4, A8, EUCLID_5: 3;

        thus P = ( Dir pw) by A3, A9, EUCLID_5: 3;

        thus P1 = ( Dir pu) by A5, A7, EUCLID_5: 3;

        

        thus (pv . 3) = (pv `3 ) by EUCLID_5:def 3

        .= 1 by EUCLID_5: 2;

        

        thus (pw . 3) = (pw `3 ) by EUCLID_5:def 3

        .= 1 by EUCLID_5: 2;

        thus pu = ((r * pv) + ((1 - r) * pw)) by A11;

      end;

      then P1 is Element of BK_model by A1, A10, Th17;

      hence contradiction by A1, BKMODEL2: 1, XBOOLE_0:def 4;

    end;

    definition

      :: BKMODEL4:def7

      func Dir001 -> non point_at_infty Element of ( ProjectiveSpace ( TOP-REAL 3)) equals ( Dir |[ 0 , 0 , 1]|);

      coherence

      proof

        reconsider P = ( Dir |[ 0 , 0 , 1]|) as Element of ( ProjectiveSpace ( TOP-REAL 3)) by ANPROJ_1: 26;

        for u be non zero Element of ( TOP-REAL 3) st P = ( Dir u) holds (u `3 ) <> 0

        proof

          let u be non zero Element of ( TOP-REAL 3);

          assume P = ( Dir u);

          then are_Prop (u, |[ 0 , 0 , 1]|) by ANPROJ_1: 22;

          then

          consider a be Real such that

           A1: a <> 0 and

           A2: u = (a * |[ 0 , 0 , 1]|) by ANPROJ_1: 1;

          u = |[(a * 0 ), (a * 0 ), (a * 1)]| by A2, EUCLID_5: 8;

          hence thesis by A1, EUCLID_5: 2;

        end;

        hence thesis by Def04;

      end;

    end

    definition

      :: BKMODEL4:def8

      func Dir101 -> non point_at_infty Element of ( ProjectiveSpace ( TOP-REAL 3)) equals ( Dir |[1, 0 , 1]|);

      coherence

      proof

        reconsider P = ( Dir |[1, 0 , 1]|) as Element of ( ProjectiveSpace ( TOP-REAL 3)) by ANPROJ_1: 26;

        for u be non zero Element of ( TOP-REAL 3) st P = ( Dir u) holds (u `3 ) <> 0

        proof

          let u be non zero Element of ( TOP-REAL 3);

          assume P = ( Dir u);

          then are_Prop (u, |[1, 0 , 1]|) by ANPROJ_1: 22;

          then

          consider a be Real such that

           A1: a <> 0 and

           A2: u = (a * |[1, 0 , 1]|) by ANPROJ_1: 1;

          u = |[(a * 1), (a * 0 ), (a * 1)]| by A2, EUCLID_5: 8;

          hence thesis by A1, EUCLID_5: 2;

        end;

        hence thesis by Def04;

      end;

    end

    theorem :: BKMODEL4:56

    for P,Q be non point_at_infty Element of ( ProjectiveSpace ( TOP-REAL 3)) st P in absolute & Q in absolute holds (( RP3_to_T2 Dir001 ),( RP3_to_T2 P)) equiv (( RP3_to_T2 Dir001 ),( RP3_to_T2 Q))

    proof

      let P,Q be non point_at_infty Element of ( ProjectiveSpace ( TOP-REAL 3));

      assume that

       A1: P in absolute and

       A2: Q in absolute ;

      reconsider p = ( RP3_to_T2 P), q = ( RP3_to_T2 Q), r = ( RP3_to_T2 Dir001 ) as Element of TarskiEuclid2Space ;

      consider u be non zero Element of ( TOP-REAL 3) such that

       A3: P = ( Dir u) & (u `3 ) = 1 & ( RP3_to_REAL2 P) = |[(u `1 ), (u `2 )]| by Def05;

      consider v be non zero Element of ( TOP-REAL 3) such that

       A4: Q = ( Dir v) & (v `3 ) = 1 & ( RP3_to_REAL2 Q) = |[(v `1 ), (v `2 )]| by Def05;

      consider w be non zero Element of ( TOP-REAL 3) such that

       A5: Dir001 = ( Dir w) & (w `3 ) = 1 & ( RP3_to_REAL2 Dir001 ) = |[(w `1 ), (w `2 )]| by Def05;

       are_Prop ( |[ 0 , 0 , 1]|,w) by A5, ANPROJ_1: 22;

      then

      consider a be Real such that a <> 0 and

       A6: w = (a * |[ 0 , 0 , 1]|) by ANPROJ_1: 1;

      w = |[(a * 0 ), (a * 0 ), (a * 1)]| by A6, EUCLID_5: 8;

      then

       A8: (w `1 ) = 0 & (w `2 ) = 0 by EUCLID_5: 2;

      reconsider u1 = (u `1 ), u2 = (u `2 ), v1 = (v `1 ), v2 = (v `2 ), w1 = (w `1 ), w2 = (w `2 ) as Real;

      now

        

         A9: (( Tn2TR ( RP3_to_T2 P)) `1 ) = (u `1 ) & (( Tn2TR ( RP3_to_T2 P)) `2 ) = (u `2 ) & (( Tn2TR ( RP3_to_T2 Q)) `1 ) = (v `1 ) & (( Tn2TR ( RP3_to_T2 Q)) `2 ) = (v `2 ) & (( Tn2TR ( RP3_to_T2 Dir001 )) `1 ) = (w `1 ) & (( Tn2TR ( RP3_to_T2 Dir001 )) `2 ) = (w `2 ) by A3, A4, A5, EUCLID: 52;

        reconsider uP = |[(u `1 ), (u `2 ), 1]| as non zero Element of ( TOP-REAL 3);

        now

          thus P in absolute by A1;

          thus P = ( Dir uP) by A3, EUCLID_5: 3;

          (uP `3 ) = 1 by EUCLID_5: 2;

          hence (uP . 3) = 1 by EUCLID_5:def 3;

        end;

        then |[(uP . 1), (uP . 2)]| in ( circle ( 0 , 0 ,1)) by BKMODEL1: 84;

        then (((uP . 1) ^2 ) + ((uP . 2) ^2 )) = 1 by BKMODEL1: 13;

        then (((uP `1 ) ^2 ) + ((uP . 2) ^2 )) = 1 by EUCLID_5:def 1;

        then (((uP `1 ) ^2 ) + ((uP `2 ) ^2 )) = 1 by EUCLID_5:def 2;

        then (((u `1 ) ^2 ) + ((uP `2 ) ^2 )) = 1 by EUCLID_5: 2;

        then

         A10: (((u `1 ) ^2 ) + ((u `2 ) ^2 )) = 1 by EUCLID_5: 2;

        reconsider vQ = |[(v `1 ), (v `2 ), 1]| as non zero Element of ( TOP-REAL 3);

        now

          thus Q in absolute by A2;

          thus Q = ( Dir vQ) by A4, EUCLID_5: 3;

          (vQ `3 ) = 1 by EUCLID_5: 2;

          hence (vQ . 3) = 1 by EUCLID_5:def 3;

        end;

        then |[(vQ . 1), (vQ . 2)]| in ( circle ( 0 , 0 ,1)) by BKMODEL1: 84;

        then (((vQ . 1) ^2 ) + ((vQ . 2) ^2 )) = 1 by BKMODEL1: 13;

        then (((vQ `1 ) ^2 ) + ((vQ . 2) ^2 )) = 1 by EUCLID_5:def 1;

        then (((vQ `1 ) ^2 ) + ((vQ `2 ) ^2 )) = 1 by EUCLID_5:def 2;

        then (((v `1 ) ^2 ) + ((vQ `2 ) ^2 )) = 1 by EUCLID_5: 2;

        then

         A11: (((v `1 ) ^2 ) + ((v `2 ) ^2 )) = 1 by EUCLID_5: 2;

        now

          

          thus ( dist (( RP3_to_T2 Dir001 ),( RP3_to_T2 P))) = ( sqrt ((( 0 - (u `1 )) ^2 ) + (( 0 - (u `2 )) ^2 ))) by A9, A8, GTARSKI2: 16

          .= ( sqrt (((u `1 ) ^2 ) + (( - (u `2 )) ^2 ))) by SQUARE_1: 3

          .= 1 by A10, SQUARE_1: 3, SQUARE_1: 18;

          

          thus ( dist (( RP3_to_T2 Dir001 ),( RP3_to_T2 Q))) = ( sqrt ((((w `1 ) - (v `1 )) ^2 ) + (((w `2 ) - (v `2 )) ^2 ))) by A9, GTARSKI2: 16

          .= ( sqrt (((v `1 ) ^2 ) + (( - (v `2 )) ^2 ))) by A8, SQUARE_1: 3

          .= 1 by A11, SQUARE_1: 3, SQUARE_1: 18;

        end;

        hence ( dist (( RP3_to_T2 Dir001 ),( RP3_to_T2 P))) = ( dist (( RP3_to_T2 Dir001 ),( RP3_to_T2 Q)));

        thus ( dist (( RP3_to_T2 Dir001 ),( RP3_to_T2 P))) = |.(( Tn2TR ( RP3_to_T2 Dir001 )) - ( Tn2TR ( RP3_to_T2 P))).| by GTARSKI2: 17;

        thus ( dist (( RP3_to_T2 Dir001 ),( RP3_to_T2 Q))) = |.(( Tn2TR ( RP3_to_T2 Dir001 )) - ( Tn2TR ( RP3_to_T2 Q))).| by GTARSKI2: 17;

      end;

      hence thesis by GTARSKI2: 18;

    end;

    theorem :: BKMODEL4:57

    

     Th48: for P,Q,R be non point_at_infty Element of ( ProjectiveSpace ( TOP-REAL 3)) holds for u,v,w be non zero Element of ( TOP-REAL 3) st P in absolute & Q in absolute & P <> Q & P = ( Dir u) & Q = ( Dir v) & R = ( Dir w) & (u `3 ) = 1 & (v `3 ) = 1 & w = |[(((u `1 ) + (v `1 )) / 2), (((u `2 ) + (v `2 )) / 2), 1]| holds R in BK_model

    proof

      let P,Q,R be non point_at_infty Element of ( ProjectiveSpace ( TOP-REAL 3));

      let u,v,w be non zero Element of ( TOP-REAL 3);

      assume that

       A1: P in absolute and

       A2: Q in absolute and

       A3: P <> Q and

       A4: P = ( Dir u) & Q = ( Dir v) & R = ( Dir w) and

       A5: (u `3 ) = 1 & (v `3 ) = 1 and

       A6: w = |[(((u `1 ) + (v `1 )) / 2), (((u `2 ) + (v `2 )) / 2), 1]|;

      

       A7: (u . 3) = 1 & (v . 3) = 1 by A5, EUCLID_5:def 3;

      reconsider u9 = |[(u . 1), (u . 2)]|, v9 = |[(v . 1), (v . 2)]| as Element of ( TOP-REAL 2);

      set M = ( the_midpoint_of_the_segment (u9,v9));

      

       A8: (w `1 ) = ((((u `1 ) + (v `1 )) * 1) / 2) & (w `2 ) = ((((u `2 ) + (v `2 )) * 1) / 2) by A6, EUCLID_5: 2;

      

       A9: M = ((1 / 2) * (u9 + v9)) by EUCLID12: 29

      .= ((1 / 2) * |[((u . 1) + (v . 1)), ((u . 2) + (v . 2))]|) by EUCLID: 56

      .= |[((((u . 1) + (v . 1)) * 1) / 2), ((((u . 2) + (v . 2)) * 1) / 2)]| by EUCLID: 58

      .= |[((((u `1 ) + (v . 1)) * 1) / 2), ((((u . 2) + (v . 2)) * 1) / 2)]| by EUCLID_5:def 1

      .= |[((((u `1 ) + (v . 1)) * 1) / 2), ((((u `2 ) + (v . 2)) * 1) / 2)]| by EUCLID_5:def 2

      .= |[((((u `1 ) + (v `1 )) * 1) / 2), ((((u `2 ) + (v . 2)) * 1) / 2)]| by EUCLID_5:def 1

      .= |[(w `1 ), (w `2 )]| by A8, EUCLID_5:def 2;

      u9 in ( circle ( 0 , 0 ,1)) & v9 in ( circle ( 0 , 0 ,1)) by A7, A1, A2, A4, BKMODEL1: 84;

      then

       A10: (( LSeg (u9,v9)) \ {u9, v9}) c= ( inside_of_circle ( 0 , 0 ,1)) by TOPREAL9: 60;

      u9 <> v9

      proof

        assume u9 = v9;

        then (u . 1) = (v . 1) & (u . 2) = (v . 2) by FINSEQ_1: 77;

        then (u `1 ) = (v . 1) & (u `2 ) = (v . 2) by EUCLID_5:def 1, EUCLID_5:def 2;

        then (u `1 ) = (v `1 ) & (u `2 ) = (v `2 ) by EUCLID_5:def 1, EUCLID_5:def 2;

        

        then u = |[(v `1 ), (v `2 ), (v `3 )]| by A5, EUCLID_5: 3

        .= v by EUCLID_5: 3;

        hence contradiction by A4, A3;

      end;

      then M <> u9 & M <> v9 by EUCLID12: 32, EUCLID12: 33;

      then

       A11: not M in {u9, v9} by TARSKI:def 2;

      M in ( LSeg (u9,v9)) by EUCLID12: 28;

      then M in (( LSeg (u9,v9)) \ {u9, v9}) by A11, XBOOLE_0:def 5;

      then

      reconsider rw = |[(w `1 ), (w `2 )]| as Element of ( inside_of_circle ( 0 , 0 ,1)) by A10, A9;

      consider RW2 be Element of ( TOP-REAL 2) such that

       A12: RW2 = rw & ( REAL2_to_BK rw) = ( Dir |[(RW2 `1 ), (RW2 `2 ), 1]|) by BKMODEL2:def 3;

      

       A13: (rw `1 ) = (w `1 ) & (rw `2 ) = (w `2 ) by EUCLID: 52;

       |[(RW2 `1 ), (RW2 `2 ), 1]| = |[(w `1 ), (w `2 ), (w `3 )]| by A12, A13, A6, EUCLID_5: 2

      .= w by EUCLID_5: 3;

      hence thesis by A12, A4;

    end;

    theorem :: BKMODEL4:58

    

     Th49: for R1,R2 be Point of TarskiEuclid2Space st ( Tn2TR R1) in ( circle ( 0 , 0 ,1)) & ( Tn2TR R2) in ( circle ( 0 , 0 ,1)) & R1 <> R2 holds ex P be Element of BK-model-Plane st between (R1,( BK_to_T2 P),R2)

    proof

      let R1,R2 be Point of TarskiEuclid2Space ;

      assume

       A1: ( Tn2TR R1) in ( circle ( 0 , 0 ,1)) & ( Tn2TR R2) in ( circle ( 0 , 0 ,1)) & R1 <> R2;

      reconsider P = ( Tn2TR R1), Q = ( Tn2TR R2) as Element of ( TOP-REAL 2);

      

       A2: P = |[(P `1 ), (P `2 )]| & Q = |[(Q `1 ), (Q `2 )]| by EUCLID: 53;

      reconsider w = |[(((P `1 ) + (Q `1 )) / 2), (((P `2 ) + (Q `2 )) / 2)]| as Element of ( TOP-REAL 2);

      reconsider u9 = |[(P `1 ), (P `2 ), 1]|, v9 = |[(Q `1 ), (Q `2 ), 1]| as non zero Element of ( TOP-REAL 3);

      reconsider w9 = |[(w `1 ), (w `2 ), 1]| as non zero Element of ( TOP-REAL 3);

      reconsider P9 = ( Dir u9), Q9 = ( Dir v9), R9 = ( Dir w9) as Point of ( ProjectiveSpace ( TOP-REAL 3)) by ANPROJ_1: 26;

      (u9 `3 ) = 1 & (v9 `3 ) = 1 by EUCLID_5: 2;

      then

      reconsider P9, Q9 as non point_at_infty Point of ( ProjectiveSpace ( TOP-REAL 3)) by Th40;

      (w9 `3 ) <> 0 by EUCLID_5: 2;

      then

      reconsider R9 as non point_at_infty Point of ( ProjectiveSpace ( TOP-REAL 3)) by Th40;

      reconsider R99 = ( RP3_to_T2 R9) as Point of TarskiEuclid2Space ;

      consider w99 be non zero Element of ( TOP-REAL 3) such that

       A3: R9 = ( Dir w99) & (w99 `3 ) = 1 & ( RP3_to_REAL2 R9) = |[(w99 `1 ), (w99 `2 )]| by Def05;

      

       A4: (w9 `1 ) = (w `1 ) & (w9 `2 ) = (w `2 ) by EUCLID_5: 2;

      (w99 . 3) = 1 & (w9 `3 ) = 1 by A3, EUCLID_5: 2, EUCLID_5:def 3;

      then (w99 . 3) = (w9 . 3) & (w9 . 3) <> 0 by EUCLID_5:def 3;

      then

       A5: w99 = w9 by A3, BKMODEL1: 43;

      

       A6: ( Tn2TR R99) = w by A3, A5, A4, EUCLID: 53;

      w = |[(((P `1 ) / 2) + ((Q `1 ) / 2)), (((P `2 ) / 2) + ((Q `2 ) / 2))]|

      .= ( |[((P `1 ) / 2), ((P `2 ) / 2)]| + |[((Q `1 ) / 2), ((Q `2 ) / 2)]|) by EUCLID: 56

      .= (((1 / 2) * |[(P `1 ), (P `2 )]|) + |[((Q `1 ) / 2), ((Q `2 ) / 2)]|) by EUCLID: 58

      .= (((1 - (1 / 2)) * P) + ((1 / 2) * Q)) by A2, EUCLID: 58;

      then w in { (((1 - r) * P) + (r * Q)) where r be Real : 0 <= r & r <= 1 };

      then

       A7: w in ( LSeg (( Tn2TR R1),( Tn2TR R2))) by RLTOPSP1:def 2;

      now

        now

          thus P9 = ( Dir u9);

          (u9 `3 ) = 1 by EUCLID_5: 2;

          hence (u9 . 3) = 1 by EUCLID_5:def 3;

          thus |[(P `1 ), (P `2 )]| in ( circle ( 0 , 0 ,1)) by A1, EUCLID: 53;

          (u9 `1 ) = (P `1 ) & (u9 `2 ) = (P `2 ) by EUCLID_5: 2;

          then (P `1 ) = (u9 . 1) & (P `2 ) = (u9 . 2) by EUCLID_5:def 1, EUCLID_5:def 2;

          hence |[(u9 . 1), (u9 . 2)]| in ( circle ( 0 , 0 ,1)) by A1, EUCLID: 53;

        end;

        then P9 is Element of absolute by BKMODEL1: 86;

        hence P9 in absolute ;

        now

          thus Q9 = ( Dir v9);

          (v9 `3 ) = 1 by EUCLID_5: 2;

          hence (v9 . 3) = 1 by EUCLID_5:def 3;

          (v9 `1 ) = (Q `1 ) & (v9 `2 ) = (Q `2 ) by EUCLID_5: 2;

          then (Q `1 ) = (v9 . 1) & (Q `2 ) = (v9 . 2) by EUCLID_5:def 1, EUCLID_5:def 2;

          hence |[(v9 . 1), (v9 . 2)]| in ( circle ( 0 , 0 ,1)) by A1, EUCLID: 53;

        end;

        then Q9 is Element of absolute by BKMODEL1: 86;

        hence Q9 in absolute ;

        thus P9 <> Q9

        proof

          assume

           A8: P9 = Q9;

          now

            thus ( Dir u9) = ( Dir v9) by A8;

            

            thus (u9 . 3) = (u9 `3 ) by EUCLID_5:def 3

            .= 1 by EUCLID_5: 2;

            

            thus (v9 . 3) = (v9 `3 ) by EUCLID_5:def 3

            .= 1 by EUCLID_5: 2;

          end;

          then u9 = v9 by BKMODEL1: 43;

          then (P `1 ) = (Q `1 ) & (P `2 ) = (Q `2 ) by FINSEQ_1: 78;

          then |[(P `1 ), (P `2 )]| = Q by EUCLID: 53;

          hence contradiction by A1, EUCLID: 53;

        end;

        thus (u9 `3 ) = 1 & (v9 `3 ) = 1 by EUCLID_5: 2;

        thus w9 = |[(((u9 `1 ) + (v9 `1 )) / 2), (((u9 `2 ) + (v9 `2 )) / 2), 1]|

        proof

          (u9 `1 ) = (P `1 ) & (v9 `1 ) = (Q `1 ) & (u9 `2 ) = (P `2 ) & (v9 `2 ) = (Q `2 ) & (w `1 ) = (((P `1 ) + (Q `1 )) / 2) & (w `2 ) = (((P `2 ) + (Q `2 )) / 2) by EUCLID: 52, EUCLID_5: 2;

          hence thesis;

        end;

      end;

      then

      reconsider AR9 = R9 as Element of BK-model-Plane by Th48;

      consider r be Element of BK_model such that

       A9: AR9 = r and

       A10: ( BK_to_T2 AR9) = ( BK_to_REAL2 r) by Def01;

      take AR9;

      now

        thus R99 = ( RP3_to_T2 R9);

        consider x be non zero Element of ( TOP-REAL 3) such that

         A11: ( Dir x) = r & (x . 3) = 1 & ( BK_to_REAL2 r) = |[(x . 1), (x . 2)]| by BKMODEL2:def 2;

        now

          thus ( Dir x) = ( Dir w9) by A11, A9;

          thus (x . 3) <> 0 by A11;

          (w9 . 3) = (w9 `3 ) by EUCLID_5:def 3

          .= 1 by EUCLID_5: 2;

          hence (x . 3) = (w9 . 3) by A11;

        end;

        then x = w9 by Th16;

        

        then ( BK_to_REAL2 r) = |[(w9 `1 ), (w9 . 2)]| by A11, EUCLID_5:def 1

        .= |[(w `1 ), (w `2 )]| by A4, EUCLID_5:def 2

        .= w by EUCLID: 53;

        hence ( RP3_to_T2 R9) = ( BK_to_T2 AR9) by A3, A5, A4, EUCLID: 53, A10;

      end;

      hence between (R1,( BK_to_T2 AR9),R2) by A7, A6, GTARSKI2: 20;

    end;

    theorem :: BKMODEL4:59

    

     Th50: for P,Q be non point_at_infty Element of ( ProjectiveSpace ( TOP-REAL 3)) st ( RP3_to_T2 P) = ( RP3_to_T2 Q) holds P = Q

    proof

      let P,Q be non point_at_infty Element of ( ProjectiveSpace ( TOP-REAL 3));

      assume

       A1: ( RP3_to_T2 P) = ( RP3_to_T2 Q);

      consider u be non zero Element of ( TOP-REAL 3) such that

       A2: P = ( Dir u) and

       A3: (u `3 ) = 1 and

       A4: ( RP3_to_REAL2 P) = |[(u `1 ), (u `2 )]| by Def05;

      consider v be non zero Element of ( TOP-REAL 3) such that

       A5: Q = ( Dir v) and

       A6: (v `3 ) = 1 and

       A7: ( RP3_to_REAL2 Q) = |[(v `1 ), (v `2 )]| by Def05;

      (v `1 ) = (u `1 ) & (v `2 ) = (u `2 ) & (v `3 ) = (u `3 ) by A1, A4, A7, A3, A6, FINSEQ_1: 77;

      then |[(u `1 ), (u `2 ), (u `3 )]| = v by EUCLID_5: 3;

      hence thesis by A2, A5, EUCLID_5: 3;

    end;

    theorem :: BKMODEL4:60

    

     Th51: for R1,R2 be non point_at_infty Element of ( ProjectiveSpace ( TOP-REAL 3)) st R1 in absolute & R2 in absolute & R1 <> R2 holds ex P be Element of BK-model-Plane st between (( RP3_to_T2 R1),( BK_to_T2 P),( RP3_to_T2 R2))

    proof

      let R1,R2 be non point_at_infty Element of ( ProjectiveSpace ( TOP-REAL 3));

      assume that

       A1: R1 in absolute & R2 in absolute and

       A2: R1 <> R2;

      consider u1 be non zero Element of ( TOP-REAL 3) such that

       A3: R1 = ( Dir u1) and

       A4: (u1 `3 ) = 1 and

       A5: ( RP3_to_REAL2 R1) = |[(u1 `1 ), (u1 `2 )]| by Def05;

      (u1 . 3) = 1 by A4, EUCLID_5:def 3;

      then |[(u1 . 1), (u1 . 2)]| in ( circle ( 0 , 0 ,1)) by A1, A3, BKMODEL1: 84;

      then

       A6: |[(u1 `1 ), (u1 . 2)]| in ( circle ( 0 , 0 ,1)) by EUCLID_5:def 1;

      consider u2 be non zero Element of ( TOP-REAL 3) such that

       A7: R2 = ( Dir u2) and

       A8: (u2 `3 ) = 1 and

       A9: ( RP3_to_REAL2 R2) = |[(u2 `1 ), (u2 `2 )]| by Def05;

      (u2 . 3) = 1 by A8, EUCLID_5:def 3;

      then |[(u2 . 1), (u2 . 2)]| in ( circle ( 0 , 0 ,1)) by A1, A7, BKMODEL1: 84;

      then

       A10: |[(u2 `1 ), (u2 . 2)]| in ( circle ( 0 , 0 ,1)) by EUCLID_5:def 1;

      reconsider P1 = ( RP3_to_T2 R1), P2 = ( RP3_to_T2 R2) as Point of TarskiEuclid2Space ;

      ( Tn2TR P1) in ( circle ( 0 , 0 ,1)) & ( Tn2TR P2) in ( circle ( 0 , 0 ,1)) & P1 <> P2 by A2, Th50, A6, A5, A9, A10, EUCLID_5:def 2;

      hence thesis by Th49;

    end;

    theorem :: BKMODEL4:61

    

     Th52: for P,Q,R be Point of TarskiEuclid2Space st between (P,Q,R) & ( Tn2TR P) in ( inside_of_circle ( 0 , 0 ,1)) & ( Tn2TR R) in ( inside_of_circle ( 0 , 0 ,1)) holds ( Tn2TR Q) in ( inside_of_circle ( 0 , 0 ,1))

    proof

      let P,Q,R be Point of TarskiEuclid2Space ;

      assume that

       A1: between (P,Q,R) and

       A2: ( Tn2TR P) in ( inside_of_circle ( 0 , 0 ,1)) & ( Tn2TR R) in ( inside_of_circle ( 0 , 0 ,1));

      ( LSeg (( Tn2TR P),( Tn2TR R))) c= ( inside_of_circle ( 0 , 0 ,1)) by A2, RLTOPSP1: 22;

      hence thesis by A1, GTARSKI2: 20;

    end;

    theorem :: BKMODEL4:62

    

     Th53: for P be non point_at_infty Element of ( ProjectiveSpace ( TOP-REAL 3)) st P in absolute holds ( RP3_to_REAL2 P) in ( circle ( 0 , 0 ,1))

    proof

      let P be non point_at_infty Element of ( ProjectiveSpace ( TOP-REAL 3));

      assume

       A1: P in absolute ;

      consider u be non zero Element of ( TOP-REAL 3) such that

       A2: P = ( Dir u) & (u `3 ) = 1 & ( RP3_to_REAL2 P) = |[(u `1 ), (u `2 )]| by Def05;

      (u . 3) = 1 by A2, EUCLID_5:def 3;

      then |[(u . 1), (u . 2)]| in ( circle ( 0 , 0 ,1)) by A1, A2, BKMODEL1: 84;

      then |[(u `1 ), (u . 2)]| in ( circle ( 0 , 0 ,1)) by EUCLID_5:def 1;

      hence thesis by A2, EUCLID_5:def 2;

    end;

    theorem :: BKMODEL4:63

    for P be non point_at_infty Element of ( ProjectiveSpace ( TOP-REAL 3)) st P in BK_model holds ( RP3_to_REAL2 P) in ( inside_of_circle ( 0 , 0 ,1))

    proof

      let P be non point_at_infty Element of ( ProjectiveSpace ( TOP-REAL 3));

      assume P in BK_model ;

      then

      reconsider P1 = P as Element of BK_model ;

      consider u be non zero Element of ( TOP-REAL 3) such that

       A1: ( Dir u) = P1 & (u . 3) = 1 and

       A2: ( BK_to_REAL2 P1) = |[(u . 1), (u . 2)]| by BKMODEL2:def 2;

       |[(u `1 ), (u . 2)]| is Element of ( inside_of_circle ( 0 , 0 ,1)) by A2, EUCLID_5:def 1;

      then

       A3: |[(u `1 ), (u `2 )]| is Element of ( inside_of_circle ( 0 , 0 ,1)) by EUCLID_5:def 2;

      consider v be non zero Element of ( TOP-REAL 3) such that

       A4: P = ( Dir v) & (v `3 ) = 1 & ( RP3_to_REAL2 P) = |[(v `1 ), (v `2 )]| by Def05;

      ( Dir v) = ( Dir u) & (u . 3) <> 0 & (u . 3) = (v . 3) by A1, A4, EUCLID_5:def 3;

      then u = v by Th16;

      hence thesis by A4, A3;

    end;

    theorem :: BKMODEL4:64

    

     Th54: for P be non point_at_infty Point of ( ProjectiveSpace ( TOP-REAL 3)) holds for Q be Element of BK_model st P = Q holds ( RP3_to_REAL2 P) = ( BK_to_REAL2 Q)

    proof

      let P be non point_at_infty Point of ( ProjectiveSpace ( TOP-REAL 3));

      let Q be Element of BK_model ;

      assume

       A1: P = Q;

      consider u be non zero Element of ( TOP-REAL 3) such that

       A2: P = ( Dir u) & (u `3 ) = 1 & ( RP3_to_REAL2 P) = |[(u `1 ), (u `2 )]| by Def05;

      consider v be non zero Element of ( TOP-REAL 3) such that

       A3: ( Dir v) = Q & (v . 3) = 1 & ( BK_to_REAL2 Q) = |[(v . 1), (v . 2)]| by BKMODEL2:def 2;

      ( Dir v) = ( Dir u) & (u . 3) <> 0 & (u . 3) = (v . 3) by A1, A2, A3, EUCLID_5:def 3;

      then u = v by Th16;

      

      then ( BK_to_REAL2 Q) = |[(u `1 ), (u . 2)]| by A3, EUCLID_5:def 1

      .= |[(u `1 ), (u `2 )]| by EUCLID_5:def 2;

      hence thesis by A2;

    end;

    theorem :: BKMODEL4:65

    

     Th55: for P,Q,R1,R2 be non point_at_infty Element of ( ProjectiveSpace ( TOP-REAL 3)) st P <> Q & P in BK_model & R1 in absolute & R2 in absolute & between (( RP3_to_T2 P),( RP3_to_T2 Q),( RP3_to_T2 R1)) & between (( RP3_to_T2 P),( RP3_to_T2 Q),( RP3_to_T2 R2)) holds R1 = R2

    proof

      let P,Q,R1,R2 be non point_at_infty Element of ( ProjectiveSpace ( TOP-REAL 3));

      assume that

       A1: P <> Q and

       A2: P in BK_model and

       A3: R1 in absolute and

       A4: R2 in absolute and

       A5: between (( RP3_to_T2 P),( RP3_to_T2 Q),( RP3_to_T2 R1)) and

       A6: between (( RP3_to_T2 P),( RP3_to_T2 Q),( RP3_to_T2 R2));

      assume R1 <> R2;

      then

      consider S be Element of BK-model-Plane such that

       A7: between (( RP3_to_T2 R1),( BK_to_T2 S),( RP3_to_T2 R2)) by A3, A4, Th51;

      set p = ( RP3_to_T2 P), q = ( RP3_to_T2 Q), r1 = ( RP3_to_T2 R1), r2 = ( RP3_to_T2 R2), s = ( BK_to_T2 S);

      ( between (p,r1,r2) or between (p,r2,r1)) & between (r1,s,r2) & between (r2,s,r1) by A7, GTARSKI1: 16, A1, A5, A6, Th50, GTARSKI3: 56;

      per cases by GTARSKI1: 19;

        suppose

         A8: between (p,r1,s);

        

         A9: ( RP3_to_REAL2 R1) in ( circle ( 0 , 0 ,1)) by A3, Th53;

        now

          thus between (p,r1,s) by A8;

          reconsider P9 = P as Element of BK_model by A2;

          ( BK_to_REAL2 P9) = ( RP3_to_REAL2 P) by Th54;

          hence ( Tn2TR p) in ( inside_of_circle ( 0 , 0 ,1));

          thus ( Tn2TR s) in ( inside_of_circle ( 0 , 0 ,1)) by Th02;

        end;

        then ( Tn2TR r1) in ( inside_of_circle ( 0 , 0 ,1)) by Th52;

        then ( RP3_to_REAL2 R1) in (( inside_of_circle ( 0 , 0 ,1)) /\ ( circle ( 0 , 0 ,1))) by A9, XBOOLE_0:def 4;

        hence contradiction by XBOOLE_0:def 7, TOPREAL9: 54;

      end;

        suppose

         A10: between (p,r2,s);

        

         A11: ( RP3_to_REAL2 R2) in ( circle ( 0 , 0 ,1)) by A4, Th53;

        now

          thus between (p,r2,s) by A10;

          reconsider P9 = P as Element of BK_model by A2;

          reconsider P99 = P9 as POINT of BK-model-Plane ;

          ( BK_to_REAL2 P9) = ( RP3_to_REAL2 P) by Th54;

          hence ( Tn2TR p) in ( inside_of_circle ( 0 , 0 ,1));

          thus ( Tn2TR s) in ( inside_of_circle ( 0 , 0 ,1)) by Th02;

        end;

        then ( Tn2TR r2) in ( inside_of_circle ( 0 , 0 ,1)) by Th52;

        then ( RP3_to_REAL2 R2) in (( inside_of_circle ( 0 , 0 ,1)) /\ ( circle ( 0 , 0 ,1))) by A11, XBOOLE_0:def 4;

        hence contradiction by XBOOLE_0:def 7, TOPREAL9: 54;

      end;

    end;

    theorem :: BKMODEL4:66

    

     Th56: for P,Q,P1,P2 be non point_at_infty Element of ( ProjectiveSpace ( TOP-REAL 3)) st P <> Q & P in BK_model & Q in BK_model & P1 in absolute & P2 in absolute & P1 <> P2 & (P,Q,P1) are_collinear & (P,Q,P2) are_collinear holds between (( RP3_to_T2 Q),( RP3_to_T2 P),( RP3_to_T2 P1)) or between (( RP3_to_T2 Q),( RP3_to_T2 P),( RP3_to_T2 P2))

    proof

      let P,Q,P1,P2 be non point_at_infty Element of ( ProjectiveSpace ( TOP-REAL 3));

      assume that

       A1: P <> Q and

       A2: P in BK_model and

       A3: Q in BK_model and

       A4: P1 in absolute and

       A5: P2 in absolute and

       A6: P1 <> P2 and

       A7: (P,Q,P1) are_collinear and

       A8: (P,Q,P2) are_collinear ;

      set P9 = ( RP3_to_T2 P), Q9 = ( RP3_to_T2 Q), P19 = ( RP3_to_T2 P1), P29 = ( RP3_to_T2 P2);

       Collinear (P9,Q9,P19) & Collinear (P9,Q9,P29) & not between (Q9,P19,P9) & not between (Q9,P29,P9) by A2, A3, A4, A5, A7, A8, Th47, Th46;

      hence thesis by A1, A2, A4, A5, A6, Th55, GTARSKI1: 16;

    end;

    theorem :: BKMODEL4:67

    

     Th57: for P,Q be Element of BK_model st P <> Q holds ex R be Element of absolute st (for p,q,r be non point_at_infty Element of ( ProjectiveSpace ( TOP-REAL 3)) st p = P & q = Q & r = R holds between (( RP3_to_T2 q),( RP3_to_T2 p),( RP3_to_T2 r)))

    proof

      let P,Q be Element of BK_model ;

      assume

       A1: P <> Q;

      then

      consider P1,P2 be Element of absolute such that

       A2: P1 <> P2 and

       A3: (P,Q,P1) are_collinear & (P,Q,P2) are_collinear by BKMODEL2: 20;

      reconsider p = P, q = Q, p1 = P1, p2 = P2 as Element of ( ProjectiveSpace ( TOP-REAL 3));

      now

        consider u be Element of ( TOP-REAL 3) such that

         A4: not u is zero and

         A5: p = ( Dir u) by ANPROJ_1: 26;

        (u . 3) <> 0 by A4, A5, BKMODEL2: 2;

        then (u `3 ) <> 0 by EUCLID_5:def 3;

        hence p is non point_at_infty by A4, A5, Th40;

        consider v be Element of ( TOP-REAL 3) such that

         A6: not v is zero and

         A7: q = ( Dir v) by ANPROJ_1: 26;

        (v . 3) <> 0 by A6, A7, BKMODEL2: 2;

        then (v `3 ) <> 0 by EUCLID_5:def 3;

        hence q is non point_at_infty by A6, A7, Th40;

        consider w be non zero Element of ( TOP-REAL 3) such that

         A8: (w . 3) = 1 and

         A9: p1 = ( Dir w) by BKMODEL3: 30;

        (w `3 ) <> 0 by A8, EUCLID_5:def 3;

        hence p1 is non point_at_infty by A9, Th40;

        consider x be non zero Element of ( TOP-REAL 3) such that

         A10: (x . 3) = 1 and

         A11: p2 = ( Dir x) by BKMODEL3: 30;

        (x `3 ) <> 0 by A10, EUCLID_5:def 3;

        hence p2 is non point_at_infty by A11, Th40;

      end;

      then

      reconsider p, q, p1, p2 as non point_at_infty Element of ( ProjectiveSpace ( TOP-REAL 3));

      per cases by A1, A2, A3, Th56;

        suppose

         A12: between (( RP3_to_T2 q),( RP3_to_T2 p),( RP3_to_T2 p1));

        take P1;

        thus thesis by A12;

      end;

        suppose

         A13: between (( RP3_to_T2 q),( RP3_to_T2 p),( RP3_to_T2 p2));

        take P2;

        thus thesis by A13;

      end;

    end;

    theorem :: BKMODEL4:68

    

     Th58: for P,Q be Element of BK_model st P <> Q holds ex R be Element of absolute st (for p,q,r be non point_at_infty Element of ( ProjectiveSpace ( TOP-REAL 3)) st p = P & q = Q & r = R holds between (( RP3_to_T2 p),( RP3_to_T2 q),( RP3_to_T2 r)))

    proof

      let P,Q be Element of BK_model ;

      assume P <> Q;

      then

      consider R be Element of absolute such that

       A1: (for p,q,r be non point_at_infty Element of ( ProjectiveSpace ( TOP-REAL 3)) st p = Q & q = P & r = R holds between (( RP3_to_T2 q),( RP3_to_T2 p),( RP3_to_T2 r))) by Th57;

      take R;

      thus thesis by A1;

    end;

    theorem :: BKMODEL4:69

    

     Th59: ( Dir |[1, 0 , 1]|) is Element of absolute

    proof

      reconsider u = |[1, 0 , 1]| as non zero Element of ( TOP-REAL 3);

      reconsider P = ( Dir u) as Element of ( ProjectiveSpace ( TOP-REAL 3)) by ANPROJ_1: 26;

      now

        

        thus (u . 3) = (u `3 ) by EUCLID_5:def 3

        .= 1 by EUCLID_5: 2;

        now

          

          thus (u . 1) = (u `1 ) by EUCLID_5:def 1

          .= 1 by EUCLID_5: 2;

          

          thus (u . 2) = (u `2 ) by EUCLID_5:def 2

          .= 0 by EUCLID_5: 2;

        end;

        then ((u . 1) * (u . 1)) = 1 & ((u . 2) * (u . 2)) = 0 ;

        then ((u . 1) ^2 ) = 1 & ((u . 2) ^2 ) = 0 by SQUARE_1:def 1;

        then (((u . 1) ^2 ) + ((u . 2) ^2 )) = 1;

        hence |[(u . 1), (u . 2)]| in ( circle ( 0 , 0 ,1)) by BKMODEL1: 13;

      end;

      then P is Element of absolute by BKMODEL1: 86;

      hence thesis;

    end;

    theorem :: BKMODEL4:70

    

     Th60: for a,b be POINT of BK-model-Plane holds (a,a) equiv (b,b)

    proof

      let a,b be POINT of BK-model-Plane ;

      reconsider A = a, B = b as Element of BK_model ;

      reconsider P = ( Dir |[1, 0 , 1]|) as Element of absolute by Th59;

      consider N be invertible Matrix of 3, F_Real such that

       A1: (( homography N) .: absolute ) = absolute and

       A2: (( homography N) . a) = b and (( homography N) . P) = P by BKMODEL2: 56;

      ( homography N) in the set of all ( homography N) where N be invertible Matrix of 3, F_Real ;

      then

      reconsider h = ( homography N) as Element of EnsHomography3 by ANPROJ_9:def 1;

      h is_K-isometry by A1, BKMODEL2:def 6;

      then h in EnsK-isometry by BKMODEL2:def 7;

      then

      reconsider h = ( homography N) as Element of SubGroupK-isometry by BKMODEL2:def 8;

      ex h be Element of SubGroupK-isometry st ex N be invertible Matrix of 3, F_Real st h = ( homography N) & (( homography N) . a) = b & (( homography N) . a) = b

      proof

        take h;

        take N;

        thus thesis by A2;

      end;

      hence thesis by BKMODEL3:def 8;

    end;

    theorem :: BKMODEL4:71

    

     Th61: for P be Element of BK_model holds P is non point_at_infty Element of ( ProjectiveSpace ( TOP-REAL 3))

    proof

      let P be Element of BK_model ;

      reconsider p = P as Element of ( ProjectiveSpace ( TOP-REAL 3));

      consider u be Element of ( TOP-REAL 3) such that

       P1: not u is zero and

       P2: p = ( Dir u) by ANPROJ_1: 26;

      (u . 3) <> 0 by P1, P2, BKMODEL2: 2;

      then (u `3 ) <> 0 by EUCLID_5:def 3;

      hence thesis by P1, P2, Th40;

    end;

    theorem :: BKMODEL4:72

    

     Th62: for P be Element of absolute holds P is non point_at_infty Element of ( ProjectiveSpace ( TOP-REAL 3))

    proof

      let P be Element of absolute ;

      consider u be non zero Element of ( TOP-REAL 3) such that

       A1: (u . 3) = 1 and

       A2: P = ( Dir u) by BKMODEL3: 30;

      (u `3 ) = 1 by A1, EUCLID_5:def 3;

      hence thesis by A2, Th40;

    end;

    theorem :: BKMODEL4:73

    

     Th63: for P be Element of BK_model holds for P9 be non point_at_infty Element of ( ProjectiveSpace ( TOP-REAL 3)) st P = P9 holds ( RP3_to_REAL2 P9) = ( BK_to_REAL2 P)

    proof

      let P be Element of BK_model ;

      let P9 be non point_at_infty Element of ( ProjectiveSpace ( TOP-REAL 3));

      assume

       A1: P = P9;

      consider u be non zero Element of ( TOP-REAL 3) such that

       A2: P9 = ( Dir u) & (u `3 ) = 1 & ( RP3_to_REAL2 P9) = |[(u `1 ), (u `2 )]| by Def05;

      consider v be non zero Element of ( TOP-REAL 3) such that

       A3: ( Dir v) = P & (v . 3) = 1 & ( BK_to_REAL2 P) = |[(v . 1), (v . 2)]| by BKMODEL2:def 2;

      ( Dir u) = ( Dir v) & (u . 3) = (v . 3) & (u . 3) <> 0 by A1, A2, A3, EUCLID_5:def 3;

      then u = v by Th16;

      then (u `1 ) = (v . 1) & (u `2 ) = (v . 2) by EUCLID_5:def 1, EUCLID_5:def 2;

      hence thesis by A2, A3;

    end;

    theorem :: BKMODEL4:74

    

     Th64: for a,q,b,c be POINT of BK-model-Plane holds ex x be POINT of BK-model-Plane st between (q,a,x) & (a,x) equiv (b,c)

    proof

      let A,Q,B,C be POINT of BK-model-Plane ;

      consider a be Element of BK_model such that

       A1: A = a and ( BK_to_T2 A) = ( BK_to_REAL2 a) by Def01;

      consider q be Element of BK_model such that

       A2: Q = q and ( BK_to_T2 Q) = ( BK_to_REAL2 q) by Def01;

      consider b be Element of BK_model such that

       A3: B = b and ( BK_to_T2 B) = ( BK_to_REAL2 b) by Def01;

      consider c be Element of BK_model such that

       A4: C = c and ( BK_to_T2 C) = ( BK_to_REAL2 c) by Def01;

      per cases ;

        suppose b <> c;

        

         A5: for q1,a1,b1,c1 be POINT of BK-model-Plane st q1 <> a1 holds ex x be POINT of BK-model-Plane st between (q1,a1,x) & (a1,x) equiv (b1,c1)

        proof

          let q1,a1,b1,c1 be POINT of BK-model-Plane ;

          assume

           A6: q1 <> a1;

          reconsider Q1 = q1, A1 = a1, B1 = b1, C1 = c1 as Element of BK_model ;

          reconsider pQ1 = Q1, pA1 = A1, pB1 = B1, pC1 = C1 as non point_at_infty Element of ( ProjectiveSpace ( TOP-REAL 3)) by Th61;

          consider qaR be Element of absolute such that

           A7: (for p,q,r be non point_at_infty Element of ( ProjectiveSpace ( TOP-REAL 3)) st p = q1 & q = a1 & r = qaR holds between (( RP3_to_T2 p),( RP3_to_T2 q),( RP3_to_T2 r))) by A6, Th58;

          reconsider pqaR = qaR as non point_at_infty Element of ( ProjectiveSpace ( TOP-REAL 3)) by Th62;

          per cases ;

            suppose

             A8: B1 = C1;

            reconsider x = a1 as Element of BK_model ;

            reconsider x as POINT of BK-model-Plane ;

            take x;

            ( Tn2TR ( BK_to_T2 a1)) in ( LSeg (( Tn2TR ( BK_to_T2 q1)),( Tn2TR ( BK_to_T2 x)))) by RLTOPSP1: 68;

            then between (( BK_to_T2 q1),( BK_to_T2 a1),( BK_to_T2 x)) by GTARSKI2: 20;

            hence between (q1,a1,x) by Th05;

            thus (a1,x) equiv (b1,c1) by A8, Th60;

          end;

            suppose

             A9: B1 <> C1;

            consider bcP be Element of absolute such that

             A10: (for p,q,r be non point_at_infty Element of ( ProjectiveSpace ( TOP-REAL 3)) st p = b1 & q = c1 & r = bcP holds between (( RP3_to_T2 p),( RP3_to_T2 q),( RP3_to_T2 r))) by A9, Th58;

            reconsider pbcP = bcP as non point_at_infty Element of ( ProjectiveSpace ( TOP-REAL 3)) by Th62;

            consider N be invertible Matrix of 3, F_Real such that

             A11: (( homography N) .: absolute ) = absolute and

             A12: (( homography N) . B1) = A1 and

             A13: (( homography N) . bcP) = qaR by BKMODEL2: 56;

            ( homography N) in the set of all ( homography N) where N be invertible Matrix of 3, F_Real ;

            then

            reconsider h = ( homography N) as Element of EnsHomography3 by ANPROJ_9:def 1;

            h is_K-isometry by A11, BKMODEL2:def 6;

            then h in EnsK-isometry by BKMODEL2:def 7;

            then

            reconsider h = ( homography N) as Element of SubGroupK-isometry by BKMODEL2:def 8;

            h = ( homography N);

            then

            reconsider x = (( homography N) . C1) as Element of BK_model by BKMODEL3: 36;

            reconsider x as POINT of BK-model-Plane ;

            reconsider px = x as non point_at_infty Element of ( ProjectiveSpace ( TOP-REAL 3)) by Th61;

            take x;

            now

              thus between (q1,a1,x)

              proof

                

                 A14: between (( RP3_to_T2 pQ1),( RP3_to_T2 pA1),( RP3_to_T2 pqaR)) by A7;

                 between (( RP3_to_T2 pB1),( RP3_to_T2 pC1),( RP3_to_T2 pbcP)) & h = ( homography N) & pB1 in BK_model & pC1 in BK_model & pbcP in absolute by A10;

                then

                 A15: between (( RP3_to_T2 pA1),( RP3_to_T2 px),( RP3_to_T2 pqaR)) by A12, A13, Th41;

                set tq = ( RP3_to_T2 pQ1), ta = ( RP3_to_T2 pA1), tx = ( RP3_to_T2 px), tr = ( RP3_to_T2 pqaR);

                

                 A16: between (tq,ta,tx) by A15, A14, GTARSKI3: 17;

                now

                  consider pp1 be Element of BK_model such that

                   A17: q1 = pp1 and

                   A18: ( BK_to_T2 q1) = ( BK_to_REAL2 pp1) by Def01;

                  consider pp2 be Element of BK_model such that

                   A19: a1 = pp2 and

                   A20: ( BK_to_T2 a1) = ( BK_to_REAL2 pp2) by Def01;

                  consider pp3 be Element of BK_model such that

                   A21: x = pp3 and

                   A22: ( BK_to_T2 x) = ( BK_to_REAL2 pp3) by Def01;

                  thus tq = ( BK_to_T2 q1) by A17, A18, Th63;

                  thus ta = ( BK_to_T2 a1) by A19, A20, Th63;

                  thus tx = ( BK_to_T2 x) by Th63, A21, A22;

                end;

                hence thesis by A16, Th05;

              end;

              ex h be Element of SubGroupK-isometry st ex N be invertible Matrix of 3, F_Real st h = ( homography N) & (( homography N) . a1) = b1 & (( homography N) . x) = c1

              proof

                

                 A23: h = ( homography N);

                reconsider M = (N ~ ) as invertible Matrix of 3, F_Real ;

                reconsider g = ( homography M) as Element of SubGroupK-isometry by A23, BKMODEL2: 47;

                take g;

                ex N be invertible Matrix of 3, F_Real st g = ( homography N) & (( homography N) . a1) = b1 & (( homography N) . x) = c1

                proof

                  take M;

                  thus thesis by A12, ANPROJ_9: 15;

                end;

                hence thesis;

              end;

              hence (a1,x) equiv (b1,c1) by BKMODEL3:def 8;

            end;

            hence thesis;

          end;

        end;

        q = a implies ex x be POINT of BK-model-Plane st between (Q,A,x) & (A,x) equiv (B,C)

        proof

          assume

           A24: q = a;

          consider Q3 be Element of BK_model such that

           A25: a <> Q3 by BKMODEL3: 11;

          reconsider q3 = Q3 as Element of BK-model-Plane ;

          consider x be POINT of BK-model-Plane such that between (q3,A,x) and

           A26: (A,x) equiv (B,C) by A25, A1, A5;

          take x;

           between (( BK_to_T2 A),( BK_to_T2 A),( BK_to_T2 x)) by GTARSKI1: 17;

          hence thesis by A26, A1, A24, A2, Th05;

        end;

        hence thesis by A1, A2, A5;

      end;

        suppose

         A27: b = c;

        set X = A;

        take X;

         between (( BK_to_T2 Q),( BK_to_T2 A),( BK_to_T2 X)) by GTARSKI1: 14;

        hence between (Q,A,X) by Th05;

        thus (A,A) equiv (B,C) by A27, A3, A4, Th60;

      end;

    end;

    theorem :: BKMODEL4:75

    

     Th65: for P,Q be POINT of BK-model-Plane st ( BK_to_T2 P) = ( BK_to_T2 Q) holds P = Q

    proof

      let P,Q be POINT of BK-model-Plane ;

      assume

       A1: ( BK_to_T2 P) = ( BK_to_T2 Q);

      (ex q be Element of BK_model st Q = q & ( BK_to_T2 Q) = ( BK_to_REAL2 q)) & (ex p be Element of BK_model st P = p & ( BK_to_T2 P) = ( BK_to_REAL2 p)) by Def01;

      hence thesis by A1, BKMODEL2: 4;

    end;

    theorem :: BKMODEL4:76

    for a,b,r be Real holds for P,Q,R be Element of ( TOP-REAL 2) st P in ( inside_of_circle (a,b,r)) & R in ( inside_of_circle (a,b,r)) holds ( LSeg (P,R)) c= ( inside_of_circle (a,b,r)) by Th15;

    begin

    theorem :: BKMODEL4:77

     BK-model-Plane is satisfying_SegmentConstruction by Th64;

    begin

    theorem :: BKMODEL4:78

     BK-model-Plane is satisfying_BetweennessIdentity

    proof

      let P,Q be POINT of BK-model-Plane ;

      assume

       A1: between (P,Q,P);

      reconsider P2 = ( BK_to_T2 P), Q2 = ( BK_to_T2 Q) as POINT of TarskiEuclid2Space ;

       between (P2,Q2,P2) by A1, Th05;

      hence thesis by GTARSKI1:def 10, Th65;

    end;

    begin

    theorem :: BKMODEL4:79

     BK-model-Plane is satisfying_Pasch

    proof

      let A,B,P,Q,Z be POINT of BK-model-Plane ;

      assume that

       A1: between (A,P,Z) and

       A2: between (B,Q,Z);

      reconsider a = A, b = B, p = P, q = Q, z = Z as Element of BK_model ;

      reconsider A2 = ( BK_to_T2 A), B2 = ( BK_to_T2 B), P2 = ( BK_to_T2 P), Q2 = ( BK_to_T2 Q), Z2 = ( BK_to_T2 Z) as POINT of TarskiEuclid2Space ;

       between (A2,P2,Z2) & between (B2,Q2,Z2) by A1, A2, Th05;

      then

      consider X2 be POINT of TarskiEuclid2Space such that

       A3: between (P2,X2,B2) and

       A4: between (Q2,X2,A2) by GTARSKI1:def 11;

      reconsider X = ( T2_to_BK X2) as POINT of BK-model-Plane ;

      

       A5: ( Tn2TR X2) in ( LSeg (( Tn2TR P2),( Tn2TR B2))) by A3, GTARSKI2: 20;

      set P9 = ( Tn2TR P2), B9 = ( Tn2TR B2);

      P9 in ( inside_of_circle ( 0 , 0 ,1)) & B9 in ( inside_of_circle ( 0 , 0 ,1)) by Th02;

      then ( Tn2TR X2) is Element of ( inside_of_circle ( 0 , 0 ,1)) by A5, Th15;

      then X2 = ( BK_to_T2 X) by Th03;

      then between (P,X,B) & between (Q,X,A) by A3, A4, Th05;

      hence thesis;

    end;