The Mizar article:

Translations in Affine Planes

by
Henryk Oryszczyszyn, and
Krzysztof Prazmowski

Received June 12, 1990

Copyright (c) 1990 Association of Mizar Users

MML identifier: TRANSLAC
[ MML identifier index ]


environ

 vocabulary DIRAF, VECTSP_1, ANALOAF, PASCH, FUNCT_2, TRANSGEO, FUNCT_1, AFF_2,
      INCSP_1, AFF_1, RELAT_1;
 notation PARTFUN1, FUNCT_2, STRUCT_0, ANALOAF, DIRAF, AFF_1, AFF_2, TRANSGEO;
 constructors AFF_1, AFF_2, TRANSGEO, MEMBERED, PARTFUN1, RELAT_2, XBOOLE_0;
 clusters STRUCT_0, RELSET_1, FUNCT_2, MEMBERED, ZFMISC_1, PARTFUN1, FUNCT_1,
      XBOOLE_0;
 requirements SUBSET, BOOLE;
 theorems FUNCT_2, TRANSGEO, AFF_1, AFF_2, FUNCT_1, DIRAF, RELAT_1;
 schemes TRANSGEO;

begin

 reserve AS for AffinSpace,
         a,b,c,d,p,q,r,s,x for Element of AS;

definition let AS;
 attr AS is Fanoian means
 :Def1: for a,b,c,d st a,b // c,d & a,c // b,d & a,d // b,c
                                   holds LIN a,b,c;
  synonym AS satisfies_Fano;
end;

Lm1: (LIN a,b,c & a<>b & a<>c & b<>c & not LIN a,b,p) implies
  (ex x st LIN p,a,x & p<>x & a<>x)
 proof assume A1: LIN a,b,c & a<>b & a<>c & b<>c & not LIN a,b,p;
  then a,b // a,c by AFF_1:def 1; then b,a // a,c by AFF_1:13;
  then consider x such that A2: p,a // a,x & p,b // c,x by A1,DIRAF:47;
    a,p // a,x by A2,AFF_1:13; then LIN a,p,x by AFF_1:def 1;
  then A3: LIN p,a,x by AFF_1:15;
  A4: now assume p = x; then p,b // p,c by A2,AFF_1:13;
   then LIN p,b,c by AFF_1:def 1; then LIN b,c,p & LIN b,c,a & LIN b,c,b
                                       by A1,AFF_1:15,16;
   hence contradiction by A1,AFF_1:17; end;
     now assume a = x;
   then p,b // a,c & a,b // a,c by A1,A2,AFF_1:13,def 1;
   then a,b // p,b by A1,AFF_1:14; then b,a // b,p by AFF_1:13;
   then LIN b,a,p by AFF_1:def 1; hence contradiction by A1,AFF_1:15; end;
  hence thesis by A3,A4;
 end;

Lm2: (LIN a,b,c & a<>b & a<>c & b<>c & not LIN a,b,p & LIN a,b,q) implies
                                      (ex x st LIN p,q,x & p<>x & q<>x)
 proof assume A1: LIN a,b,c & a<>b & a<>c & b<>c & not LIN a,b,p & LIN a,b,q;

   A2: now assume A3: q = b & q<>a & q<>c;
    then LIN q,a,c & not LIN q,a,p by A1,AFF_1:15;
    hence thesis by A1,A3,Lm1; end;
   A4: now assume A5: q = c & q<>a & q<>b;
      now assume LIN q,a,p;
     then LIN c,a,p & LIN c,a,b & LIN c,a,a by A1,A5,AFF_1:15,16;
     hence contradiction by A1,AFF_1:17; end;
    then LIN q,a,b & not LIN q,a,p by A1,AFF_1:15;
    hence thesis by A1,A5,Lm1; end;
      now assume A6: q<>a & q<>b & q<>c;
      now assume LIN q,a,p; then LIN a,q,p & LIN a,q,b by A1,AFF_1:15;
     then a,q // a,p & a,q // a,b by AFF_1:def 1; then a,b // a,p by A6,AFF_1:
14;
     hence contradiction by A1,AFF_1:def 1; end;
    then LIN q,a,b & not LIN q,a,p by A1,AFF_1:15;
    hence thesis by A1,A6,Lm1; end;
   hence thesis by A1,A2,A4,Lm1;
 end;

Lm3: (LIN a,b,c & a<>b & a<>c & b<>c & not LIN a,b,p & p<>q & p,q // a,b)
                              implies (ex x st LIN p,q,x & p<>x & q<>x)
 proof assume A1:
        LIN a,b,c & a<>b & a<>c & b<>c & not LIN a,b,p & p<>q & p,q // a,b;
  A2: a<>q proof assume a = q; then a,p // a,b by A1,AFF_1:13;
   then LIN a,p,b by AFF_1:def 1; hence contradiction by A1,AFF_1:15; end;
  A3: b<>q proof assume b = q; then b,p // b,a by A1,AFF_1:13;
   then LIN b,p,a by AFF_1:def 1; hence contradiction by A1,AFF_1:15; end;
  A4: not LIN a,b,q proof assume A5: LIN a,b,q; then a,b // a,q by AFF_1:def 1
;
   then p,q // a,q by A1,AFF_1:14; then q,p // q,a by AFF_1:13;
   then LIN q,p,a by AFF_1:def 1;
   then LIN q,a,p & LIN q,a,b & LIN q,a,a by A5,AFF_1:15,16;
   hence contradiction by A1,A2,AFF_1:17; end;
  A6: not LIN a,c,p proof assume LIN a,c,p;
   then LIN a,c,p & LIN a,c,b & LIN a,c,a by A1,AFF_1:15,16;
   hence contradiction by A1,AFF_1:17; end;
  consider r such that A7: b,c // q,r & b,q // c,r by DIRAF:47;
    LIN b,a,c by A1,AFF_1:15; then b,a // b,c by AFF_1:def 1;
  then b,a // q,r by A1,A7,AFF_1:14; then a,b // q,r by AFF_1:13;
  then p,q // q,r by A1,AFF_1:14; then q,p // q,r by AFF_1:13;
  then LIN q,p,r by AFF_1:def 1; then A8: LIN p,q,r by AFF_1:15;
  A9: q<>r proof assume q = r; then q,b // q,c by A7,AFF_1:13;
   then LIN q,b,c by AFF_1:def 1;
   then LIN b,c,q & LIN b,c,a & LIN b,c,b by A1,AFF_1:15,16;
   hence contradiction by A1,A4,AFF_1:17; end;
     now assume A10: p = r;
   consider s such that A11: b,a // q,s & b,q // a,s by DIRAF:47;
   A12: now assume p = s;
   then a,p // c,p by A3,A7,A10,A11,AFF_1:14; then p,a // p,c by AFF_1:13;
   then LIN p,a,c by AFF_1:def 1; hence contradiction by A6,AFF_1:15; end;
   A13: q<>s proof assume q = s; then q,b // q,a by A11,AFF_1:13;
    then LIN q,b,a by AFF_1:def 1; hence contradiction by A4,AFF_1:15; end;
     a,b // q,s by A11,AFF_1:13; then p,q // q,s by A1,AFF_1:14;
   then q,p // q,s by AFF_1:13; then LIN q,p,s by AFF_1:def 1;
   then LIN p,q,s by AFF_1:15; hence thesis by A12,A13; end;
  hence thesis by A8,A9;
 end;

canceled;

theorem Th2:
 (ex a,b,c st LIN a,b,c & a<>b & a<>c & b<>c) implies
   (for p,q st p<>q holds (ex r st LIN p,q,r & p<>r & q<>r))
 proof given a,b,c such that A1: LIN a,b,c & a<>b & a<>c & b<>c;
  let p,q such that A2: p<>q;
  A3: now assume A4: LIN a,b,p & LIN a,b,q;
   then A5: LIN p,q,c by A1,AFF_1:17;
     LIN a,b,a & LIN a,b,b by AFF_1:16;
   then A6: LIN p,q,a & LIN p,q,b by A1,A4,AFF_1:17;
      now assume A7: p = c or q = c;
       now assume p <> a or q <> b;
     A8: now assume A9: p = c & p<>a;
      then q = b implies thesis by A1,A6;
      hence thesis by A1,A6,A9; end;
        now assume A10: q = c & q<>b;
      then p = b implies thesis by A1,A6;
      hence thesis by A6,A10; end;
     hence thesis by A1,A7,A8; end;
    hence thesis by A1; end;
   hence thesis by A5;
      end;
  A11: now assume not LIN a,b,q & LIN a,b,p; then consider x such that
   A12: LIN q,p,x & q<>x & p<>x by A1,Lm2;
     LIN p,q,x by A12,AFF_1:15; hence thesis by A12; end;
     now assume A13: not LIN a,b,p & not LIN a,b,q;
      now assume A14: not p,q // a,b;
    consider p' being Element of AS such that
    A15: a,b // p,p' & p<>p' by DIRAF:47; p,p' // a,b by A15,AFF_1:13;
    then A16: ex p'' being Element of AS st
 LIN p,p',p'' & p<>p'' & p'<>p'' by A1,A13,A15,Lm3;
      not LIN p,p',q proof assume LIN p,p',q; then p,p' // p,q by AFF_1:def 1
;
     hence contradiction by A14,A15,AFF_1:14; end;
    then consider r such that A17: LIN q,p,r & q<>r & p<>r by A15,A16,Lm1;
      LIN p,q,r by A17,AFF_1:15;
    hence thesis by A17; end;
   hence thesis by A1,A2,A13,Lm3; end;
  hence thesis by A1,A3,A11,Lm2;
 end;

 reserve AFP for AffinPlane,
         a,a',b,b',c,c',d,p,p',q,q',r,x,x',y,y',z
                        for Element of AFP,
         A,C,P for Subset of AFP,
         f,g,h,f1,f2 for Permutation of the carrier of AFP;

canceled;

theorem Th4: (AFP satisfies_Fano &
 a,b // c,d & a,c // b,d & not LIN a,b,c) implies ex p st LIN b,c,p & LIN a,d,p
 proof assume that
  A1: for a,b,c,d st a,b // c,d & a,c // b,d & a,d // b,c holds LIN a,b,c and
  A2: a,b // c,d & a,c // b,d & not LIN a,b,c;
    not a,d // b,c by A1,A2; then ex p st LIN a,d,p & LIN b,c,p by AFF_1:74;
  hence thesis;
 end;

Lm4: not LIN a,b,x & a,b // x,y & x<>y implies
        not LIN x,y,a & not LIN b,a,y & not LIN y,x,b
  proof assume that A1: not LIN a,b,x and
                    A2: a,b // x,y and A3: x<>y;
   thus not LIN x,y,a
     proof assume LIN x,y,a;
       then LIN x,y,a & x,y // a,b by A2,AFF_1:13;
       then LIN x,y,a & LIN x,y,b & LIN x,y,x by A3,AFF_1:16,18;
      hence contradiction by A1,A3,AFF_1:17;
     end;
   thus not LIN b,a,y
     proof assume LIN b,a,y;
       then LIN b,a,y & b,a // y,x & b<>a by A1,A2,AFF_1:13,16;
       then LIN b,a,x by AFF_1:18;
      hence contradiction by A1,AFF_1:15;
     end;
   thus not LIN y,x,b
     proof assume LIN y,x,b;
       then LIN y,x,b & y,x // b,a by A2,AFF_1:13;
       then LIN y,x,b & LIN y,x,a & LIN y,x,x by A3,AFF_1:16,18;
      hence contradiction by A1,A3,AFF_1:17;
     end;
 end;

  Lm5: not LIN a,b,x & a,b // x,y & a,x // b,y implies
          not LIN x,y,a & not LIN b,a,y & not LIN y,x,b
    proof assume that A1: not LIN a,b,x and
                      A2: a,b // x,y & a,x // b,y;
        x<>y
       proof assume x=y;
         then x,a // x,b by A2,AFF_1:13; then LIN x,a,b by AFF_1:def 1;
        hence contradiction by A1,AFF_1:15;
       end;
     hence thesis by A1,A2,Lm4;
    end;

theorem
Th5: f is_Tr & not LIN a,f.a,x & a,f.a // x,y & a,x // f.a,y
                                                implies y=f.x
  proof assume A1: f is_Tr; then A2: f is_Dil by TRANSGEO:def 11;
    assume A3: not LIN a,f.a,x & a,f.a // x,y & a,x // f.a,y;
      a,x // f.a,f.x & a,f.a // x,f.x by A1,A2,TRANSGEO:85,100;
   hence thesis by A3,TRANSGEO:97;
  end;

theorem
 Th6: AFP satisfies_des iff
  (for a,a',b,c,b',c' st not LIN a,a',b & not LIN a,a',c & a,a' // b,b' &
    a,a' // c,c' & a,b // a',b' & a,c // a',c' holds b,c // b',c')
   proof
    thus AFP satisfies_des implies
    (for a,a',b,c,b',c' st not LIN a,a',b & not LIN a,a',c & a,a' // b,b' &
             a,a' // c,c' & a,b // a',b' & a,c // a',c' holds b,c // b',c')
     proof assume A1: AFP satisfies_des;

      let a,a',b,c,b',c';
       assume A2:  not LIN a,a',b & not LIN a,a',c & a,a' // b,b' &
                  a,a' // c,c' & a,b // a',b' & a,c // a',c';
       set A=Line(a,a'), P=Line(b,b'), C=Line(c,c');
       A3: a<>a' & a<>b & a'<>b & a<>c & a'<>c by A2,AFF_1:16;
       A4: b<>b' proof assume b=b'; then b,a // b,a' by A2,AFF_1:13;
        then LIN
 b,a,a' by AFF_1:def 1; hence contradiction by A2,AFF_1:15; end;
       A5: c <>c' proof assume c = c'; then c,a // c,a' by A2,AFF_1:13;
        then LIN
 c,a,a' by AFF_1:def 1; hence contradiction by A2,AFF_1:15; end;
       A6: a in A & a' in A & b in P & b' in P & c in C & c' in C by AFF_1:26;
       A7: A is_line & P is_line & C is_line by A3,A4,A5,AFF_1:def 3;
       A8: A // P & A // C by A2,A3,A4,A5,AFF_1:51;
       A9: A<>P by A2,A6,A7,AFF_1:33;
          A<>C by A2,A6,A7,AFF_1:33;
       hence thesis by A1,A2,A6,A7,A8,A9,AFF_2:def 11; end;
    assume
     A10: for a,a',b,c,b',c' st not LIN a,a',b & not LIN
 a,a',c & a,a' // b,b' &
             a,a' // c,c' & a,b // a',b' & a,c // a',c' holds b,c // b',c';
       now let A,P,C,a,b,c,a',b',c';
      assume A11: A // P & A // C & a in A & a' in A &
      b in P & b' in P & c in C & c' in C & A is_line & P is_line &
      C is_line & A<>P & A<>C & a,b // a',b' & a,c // a',c';
      then A12: a,a' // b,b' & a,a' // c,c' by AFF_1:53;
      A13: now assume A14: a=a';
       then LIN a,b,b' by A11,AFF_1:def 1; then LIN b,b',a by AFF_1:15;
then A15:       b=b' or a in P by A11,AFF_1:39;
         LIN a,c,c' by A11,A14,AFF_1:def 1;
       then LIN c,c',a by AFF_1:15; then c = c' or a in C by A11,AFF_1:39;
       hence b,c // b',c' by A11,A15,AFF_1:11,59; end;
         now assume A16: a<>a';
       A17: not LIN a,a',b proof assume LIN a,a',b;
        then b in A by A11,A16,AFF_1:39; hence contradiction by A11,AFF_1:59;
end;
          not LIN a,a',c proof assume LIN a,a',c;
        then c in A by A11,A16,AFF_1:39; hence contradiction by A11,AFF_1:59;
end;
       hence b,c // b',c' by A10,A11,A12,A17; end;
      hence b,c // b',c' by A13; end;
     hence thesis by AFF_2:def 11;
   end;

theorem
Th7: ex f st f is_Tr & f.a=a
  proof
  take id the carrier of AFP;
   thus thesis by FUNCT_1:35,TRANSGEO:99;
  end;

Lm6: a<>b implies ex y st
      ((not LIN a,b,x & a,b // x,y & a,x // b,y) or
      (LIN a,b,x & ex p,q st not LIN a,b,p & a,b // p,q &
                    a,p // b,q & p,q // x,y & p,x // q,y))
  proof assume A1: a<>b;
    A2: now assume A3: not LIN a,b,x; ex y st
 a,b // x,y & a,x // b,y by DIRAF:47;
         hence thesis by A3; end;
      now assume A4: LIN a,b,x; consider p such that
                              A5: not LIN a,b,p by A1,AFF_1:22;
       consider q such that
                       A6: a,b // p,q & a,p // b,q by DIRAF:47;
          ex y st p,q // x,y & p,x // q,y by DIRAF:47;
      hence thesis by A4,A5,A6;
     end;
    hence thesis by A2;
   end;

Lm7: a<>b implies ex x st
       (not LIN a,b,x & a,b // x,y & a,x // b,y) or
       (LIN a,b,x & (ex p,q st not LIN a,b,p & a,b // p,q &
                       a,p // b,q & p,q // x,y & p,x // q,y))
  proof assume A1: a<>b;
    A2: now assume not LIN a,b,y; then A3: not LIN b,a,y by AFF_1:15;
          consider x such that
                        A4: b,a // y,x & b,y // a,x by DIRAF:47;
          A5: not LIN a,b,x by A3,A4,Lm5;
            a,b // x,y & a,x // b,y by A4,AFF_1:13;
         hence thesis by A5;
        end;
      now assume A6: LIN a,b,y;
      consider p such that A7: not LIN a,b,p by A1,AFF_1:22;
      consider q such that A8: a,b // p,q & a,p // b,q by DIRAF:47;
      consider x such that A9: q,p // y,x & q,y // p,x by DIRAF:47;
      A10: p,q // x,y & p,x // q,y by A9,AFF_1:13;
        LIN a,b,x
        proof
          A11: a,b // x,y or p=q by A8,A10,AFF_1:14;
            now assume p=q;
          then p,a // p,b by A8,AFF_1:13;
          then LIN p,a,b by AFF_1:def 1;
         hence contradiction by A7,AFF_1:15;
        end;
        then a,b // y,x by A11,AFF_1:13;
       hence LIN a,b,x by A1,A6,AFF_1:18;
      end;
     hence thesis by A7,A8,A10;
    end;
   hence thesis by A2;
  end;

Lm8: AFP satisfies_des &
     a<>b & LIN a,b,x & a,b // p,q & a,b // p',q' & a,p // b,q &
      a,p' // b,q' & p,q // x,y & p',q' // x,y' & p,x // q,y &
      p',x // q',y' & not LIN a,b,p & not LIN a,b,p' & not LIN
 p,q,p' implies y=y'
  proof assume that A1: AFP satisfies_des and
    A2: a<>b and A3: LIN a,b,x and A4: a,b // p,q
    and A5: a,b // p',q' and A6: a,p // b,q and A7: a,p' // b,q'
    and A8: p,q // x,y and A9: p',q' // x,y' and A10: p,x // q,y
    and A11: p',x // q',y' and A12: not LIN a,b,p
    and A13: not LIN a,b,p' and A14: not LIN p,q,p';
    A15: p,p' // q,q' by A1,A4,A5,A6,A7,A12,A13,Th6;
    A16: p,q // p',q' by A2,A4,A5,AFF_1:14;
    A17: p<>q
      proof assume p=q;
        then p,a // p,b by A6,AFF_1:13; then LIN p,a,b by AFF_1:def 1;
       hence contradiction by A12,AFF_1:15;
      end;
    A18: p'<>q'
      proof assume p'=q';
        then p',a // p',b by A7,AFF_1:13; then LIN p',a,b by AFF_1:def 1;
       hence contradiction by A13,AFF_1:15;
      end;
      not LIN p,q,x
      proof assume A19: LIN p,q,x;
        then A20: p,q // p,x by AFF_1:def 1;
        A21: x<>a by A4,A6,A12,A19,Lm5;
          p,x // a,b & a,b // a,x by A3,A4,A17,A20,AFF_1:14,def 1;
        then p,x // a,x by A2,AFF_1:14;
        then x,p // x,a by AFF_1:13;
        then LIN x,p,a & LIN x,p,x & LIN
 a,x,b by A3,AFF_1:15,16,def 1;
        then LIN x,p,a & LIN x,p,b & LIN x,p,p by A21,AFF_1:16,20;
       hence contradiction by A3,A12,AFF_1:17;
      end;
    then A22: p',x // q',y by A1,A8,A10,A14,A15,A16,Th6;
    A23: not LIN p',q',x
      proof assume A24: LIN p',q',x;
        then A25: p',q' // p',x by AFF_1:def 1;
        A26: x<>a by A5,A7,A13,A24,Lm5;
          p',x // a,b & a,b // a,x by A3,A5,A18,A25,AFF_1:14,def 1;
        then p',x // a,x by A2,AFF_1:14;
        then x,p' // x,a by AFF_1:13;
        then LIN x,p',a & LIN x,p',x & LIN
 a,x,b by A3,AFF_1:15,16,def 1;
        then LIN x,p',a & LIN x,p',b & LIN x,p',p' by A26,AFF_1:16,20;
       hence contradiction by A3,A13,AFF_1:17;
      end;
      p',q' // x,y by A8,A16,A17,AFF_1:14;
   hence thesis by A9,A11,A22,A23,TRANSGEO:97;
  end;

theorem
Th8: (for p,q,r st p<>q & LIN p,q,r holds r = p or r = q) & a,b // p,q &
     a,p // b,q & not LIN a,b,p implies a,q // b,p
 proof assume that A1: for p,q,r st p<>q & LIN p,q,r holds r = p or r = q
           and A2: a,b // p,q & a,p // b,q & not LIN a,b,p;
   A3: a<>b & a<>p & b<>p by A2,AFF_1:16;
   A4: p<>q proof assume p=q; then p,a // p,b by A2,AFF_1:13;
    then LIN p,a,b by AFF_1:def 1; hence contradiction by A2,AFF_1:15; end;
   A5: not LIN a,p,q proof assume LIN a,p,q;
    then LIN p,q,a & p,q // a,b by A2,AFF_1:13,15;
    then LIN p,q,b & LIN p,q,a & LIN p,q,p by A4,AFF_1:16,18;
    hence contradiction by A2,A4,AFF_1:17; end;
   consider z such that A6: q,p // a,z & q,a // p,z by DIRAF:47;
     p,q // a,z by A6,AFF_1:13; then a,b // a,z by A2,A4,AFF_1:14;
   then LIN a,b,z by AFF_1:def 1; then A7: a=z or b=z by A1,A3;
      now assume a=z; then a,p // a,q by A6,AFF_1:13;
    hence contradiction by A5,AFF_1:def 1; end;hence thesis by A6,A7,AFF_1:13
;
 end;

Lm9: AFP satisfies_des &
      a<>b & LIN a,b,x & a,b // p,q & a,b // p',q' & a,p // b,q &
       a,p' // b,q' & p,q // x,y & p',q' // x,y' & p,x // q,y &
       p',x // q',y' & not LIN a,b,p & not LIN a,b,p' implies y=y'
  proof assume A1: AFP satisfies_des & a<>b & LIN a,b,x & a,b // p,q &
     a,b // p',q' & a,p // b,q & a,p' // b,q' & p,q // x,y &
     p',q' // x,y' & p,x // q,y & p',x // q',y' &
     not LIN a,b,p & not LIN a,b,p';
    then A2: a<>p & a<>p' by AFF_1:16;
    A3: p<>q proof assume p=q;
       then p,a // p,b by A1,AFF_1:13; then LIN p,a,b by AFF_1:def 1;
       hence contradiction by A1,AFF_1:15; end;
    A4: p'<>q' proof assume p'=q';
     then p',a // p',b by A1,AFF_1:13; then LIN p',a,b by AFF_1:def 1;
     hence contradiction by A1,AFF_1:15; end;
    A5: not LIN p,q,x proof assume LIN p,q,x; then p,q // p,x by AFF_1:def 1;
     then a,b // p,x by A1,A3,AFF_1:14; then a,b // x,p by AFF_1:13;
     hence contradiction by A1,AFF_1:18; end;
A6: not LIN p',q',x proof assume LIN
 p',q',x; then p',q' // p',x by AFF_1:def 1;
     then a,b // p',x by A1,A4,AFF_1:14; then a,b // x,p' by AFF_1:13;
     hence contradiction by A1,AFF_1:18; end;
    A7: x<>y & x<>y' proof
       now assume x=y; then x,p // x,q by A1,AFF_1:13;
      then LIN x,p,q by AFF_1:def 1; hence contradiction by A5,AFF_1:15; end;
     hence x<>y;
       now assume x=y'; then x,p' // x,q' by A1,AFF_1:13;
      then LIN x,p',q' by AFF_1:def 1; hence contradiction by A6,AFF_1:15;
end;
     hence x<>y'; end;
    A8: LIN a,b,y proof a,b // x,y by A1,A3,AFF_1:14;
     hence thesis by A1,AFF_1:18; end;
    A9: not LIN q,p,b proof assume A10: LIN q,p,b; q,p // b,a by A1,AFF_1:13;
     then LIN q,p,a & LIN q,p,p by A3,A10,AFF_1:16,18;
     hence contradiction by A1,A3,A10,AFF_1:17; end;
      now assume A11: LIN p,q,p';
     A12: LIN p,q,q' proof p,q // p',q' by A1,AFF_1:14;
      hence LIN p,q,q' by A3,A11,AFF_1:18; end;
     A13: now assume A14:for x st LIN a,p,x holds x=a or x=p;
      then A15: for p,q,r st p<>q & LIN p,q,r holds r = p or r = q by A2,Th2;
      A16: now assume A17: p=p';
        then q=q' by A2,A3,A4,A12,A14,Th2;
       hence y=y' by A1,A5,A17,TRANSGEO:97; end;
        now assume A18: q=p';

       A19: now assume A20: a=x;
          then A21: b=y by A1,A7,A8,A14,Th2;
            a,q // b,p by A1,A15,Th8;
          then A22: q,p // a,b & q,a // p,b by A1,AFF_1:13;
          A23: q,p // a,y' & q,a // p,y' by A1,A3,A4,A12,A14,A18,A20,Th2;
            not LIN q,p,a by A5,A20,AFF_1:15;
          hence y=y' by A21,A22,A23,TRANSGEO:97; end;
          now assume A24: b=x;
          then A25: a=y by A1,A2,A7,A8,A14,Th2;
            q,p // b,a & q,p // b,y' & q,b // p,a & q,b // p,y'
                              by A1,A2,A3,A4,A12,A14,A18,A24,Th2,AFF_1:13;
          hence y=y' by A9,A25,TRANSGEO:97; end;
      hence y=y' by A1,A2,A14,A19,Th2; end;
      hence y=y' by A2,A3,A11,A14,A16,Th2; end;

        now given p'' being Element of AFP such that
      A26: LIN a,p,p'' & p''<>a & p''<>p;
      consider q'' being Element of AFP such that
      A27: a,b // p'',q'' and A28: a,p'' // b,q'' by DIRAF:47;
      consider y'' being Element of AFP such that
      A29: p'',q'' // x,y'' and A30: p'',x // q'',y'' by DIRAF:47;
      A31: not LIN p,q,p''
        proof assume LIN p,q,p'';
          then LIN p,p'',p & LIN p,p'',q & LIN
 p,p'',a by A26,AFF_1:15,16;
          then LIN p,q,a by A26,AFF_1:17;
         hence contradiction by A1,Lm5;
        end;
      A32: not LIN p',q',p''
        proof assume A33: LIN p',q',p'';
            p,q // p',q' by A1,AFF_1:14;
          then LIN p,q,q' by A3,A11,AFF_1:18;
         hence contradiction by A4,A11,A31,A33,AFF_1:20;
        end;
         not LIN a,b,p''
        proof assume LIN a,b,p'';
          then LIN a,p'',a & LIN a,p'',b & LIN
 a,p'',p by A26,AFF_1:15,16;
         hence contradiction by A1,A26,AFF_1:17;
        end;
      then y=y'' & y'=y'' by A1,A27,A28,A29,A30,A31,A32,Lm8;
     hence y=y'; end;
    hence y=y' by A13; end;
   hence thesis by A1,Lm8;
  end;

Lm10: a<>b & LIN a,b,x & a,b // p,q & a,p // b,q & p,q // x,y &
                not LIN a,b,p implies p<>q & LIN a,b,y
  proof assume that A1: a<>b and A2: LIN a,b,x and A3: a,b // p,q
    and A4: a,p // b,q and A5: p,q // x,y and
    A6: not LIN a,b,p;
   thus p<>q
     proof assume p=q;
       then p,a // p,b by A4,AFF_1:13;
       then LIN p,a,b by AFF_1:def 1;
      hence contradiction by A6,AFF_1:15;
     end;
    then a,b // x,y by A3,A5,AFF_1:14;
   hence LIN a,b,y by A1,A2,AFF_1:18;
  end;

Lm11: AFP satisfies_des &
     a<>b & LIN a,b,x & a,b // p,q & a,b // p',q' &
     a,p // b,q & a,p' // b,q' & p,q // x,y & p,x // q,y &
     p',q' // x',y & p',x' // q',y & not LIN a,b,p & not LIN a,b,p'
                                                  implies x=x'
  proof assume that A1: AFP satisfies_des and
    A2: a<>b and A3: LIN a,b,x
    and A4: a,b // p,q and A5: a,b // p',q' and A6: a,p // b,q
    and A7: a,p' // b,q' and A8: p,q // x,y and A9: p,x // q,y
    and A10: p',q' // x',y and A11: p',x' // q',y and
    A12: not LIN a,b,p and A13: not LIN a,b,p';
      LIN a,b,y by A2,A3,A4,A6,A8,A12,Lm10;
    then A14: LIN b,a,y by AFF_1:15;
    A15: b,a // q,p by A4,AFF_1:13;
    A16: b,a // q',p' by A5,AFF_1:13;
    A17: b,q // a,p by A6,AFF_1:13;
    A18: b,q' // a,p' by A7,AFF_1:13;
    A19: q,p // y,x by A8,AFF_1:13;
    A20: q,y // p,x by A9,AFF_1:13;
    A21: q',p' // y,x' by A10,AFF_1:13;
    A22: q',y // p',x' by A11,AFF_1:13;
    A23: not LIN b,a,q by A4,A6,A12,Lm5;
       not LIN b,a,q' by A5,A7,A13,Lm5;
   hence x=x' by A1,A2,A14,A15,A16,A17,A18,A19,A20,A21,A22,A23,Lm9;
  end;

Lm12: AFP satisfies_des & a<>b implies ex f st f is_Tr & f.a=b
  proof
   defpred X[Element of AFP,Element of AFP] means
          (not LIN a,b,$1 & a,b // $1,$2 & a,$1 // b,$2) or
          (LIN a,b,$1 & (ex p,q st not LIN a,b,p & a,b // p,q &
          a,p // b,q & p,q // $1,$2 & p,$1 // q,$2));
   assume A1: AFP satisfies_des & a<>b;
    then A2: ex y st X[x,y] by Lm6;
    A3: ex x st X[x,y] by A1,Lm7;
    A4: X[x,y] & X[x,y'] implies y=y' by A1,Lm9,TRANSGEO:97;
    A5: X[x,y] & X[x',y] implies x=x'
     proof assume A6:((not LIN a,b,x & a,b // x,y & a,x // b,y) or
        (LIN a,b,x & ex p,q st not LIN a,b,p & a,b // p,q &
                     a,p // b,q & p,q // x,y & p,x // q,y)) &
         ((not LIN a,b,x' & a,b // x',y & a,x' // b,y) or
         (LIN a,b,x' & ex p,q st not LIN a,b,p & a,b // p,q &
                    a,p // b,q & p,q // x',y & p,x' // q,y));
       A7: now assume A8: not LIN a,b,y;
             then A9: not LIN b,a,y by A1,A6,Lm5,Lm10;
             A10: b,a // y,x & b,y // a,x by A1,A6,A8,Lm10,AFF_1:13;
               b,a // y,x' & b,y // a,x' by A1,A6,A8,Lm10,AFF_1:13;
           hence x=x' by A9,A10,TRANSGEO:97;
          end;
         now assume A11: LIN a,b,y;
         A12: not (not LIN a,b,x & a,b // x,y & a,x // b,y)
           proof assume A13: not LIN a,b,x & a,b // x,y & a,x // b,y;
             then a,b // y,x by AFF_1:13;
            hence contradiction by A1,A11,A13,AFF_1:18;
           end;
            not (not LIN a,b,x' & a,b // x',y & a,x' // b,y)
           proof assume A14: not LIN a,b,x' & a,b // x',y & a,x' // b,y;
             then a,b // y,x' by AFF_1:13;
            hence contradiction by A1,A11,A14,AFF_1:18;
           end;
        hence x=x' by A1,A6,A12,Lm11;
       end;
      hence x=x' by A7;
     end;
       ex f st for x,y holds f.x=y iff X[x,y]
                                        from EXPermutation(A2,A3,A5,A4);
     then consider f such that A15: for x,y holds f.x=y iff
      (not LIN a,b,x & a,b // x,y & a,x // b,y) or
      (LIN a,b,x & (ex p,q st not LIN a,b,p & a,b // p,q &
                   a,p // b,q & p,q // x,y & p,x // q,y));
     A16: a,b // x,f.x
       proof set y=f.x;
           now assume A17: LIN a,b,x; then consider p,q such that
           A18: not LIN a,b,p & a,b // p,q & a,p // b,q &
                             p,q // x,y & p,x // q,y by A15;
             p<>q by A1,A17,A18,Lm10;
          hence a,b // x,f.x by A18,AFF_1:14;
         end;
        hence a,b // x,f.x by A15;
       end;
     A19: x,f.x // y,f.y
       proof a,b // x,f.x & a,b // y,f.y by A16;
        hence x,f.x // y,f.y by A1,AFF_1:14;
       end;

        for x,y holds x,y // f.x,f.y
       proof let x,y;
         A20: now assume A21: not LIN a,b,x & not LIN a,b,y;
               then a,x // b,f.x & a,y // b,f.y &
               a,b // x,f.x & a,b // y,f.y by A15;
              hence thesis by A1,A21,Th6;
             end;
         A22: now assume A23: LIN a,b,x & LIN a,b,y;
               then A24: a,b // x,y by AFF_1:19;
                 a,b // x,f.x & a,b // y,f.y by A16;
               then LIN a,b,f.x & LIN a,b,f.y by A1,A23,AFF_1:18;
               then a,b // f.x,f.y by AFF_1:19;
              hence thesis by A1,A24,AFF_1:14;
             end;
         A25: now assume A26: LIN a,b,x & not LIN a,b,y;
               then A27: a,b // y,f.y & a,y // b,f.y by A15;
                  ex x' st y,f.y // x,x' & y,x // f.y,x' by DIRAF:47;
               then y,x // f.y,f.x by A15,A26,A27;
              hence thesis by AFF_1:13;
             end;
            now assume A28: not LIN a,b,x & LIN a,b,y;
               then A29: a,b // x,f.x & a,x // b,f.x by A15;
                  ex y' st x,f.x // y,y' & x,y // f.x,y' by DIRAF:47;
              hence thesis by A15,A28,A29;
             end;
        hence thesis by A20,A22,A25;
       end;
       then f is_Dil by TRANSGEO:85;
     then A30: f is_Tr by A19,TRANSGEO:100;
       f.a=b
       proof consider p such that A31: not LIN a,b,p by A1,AFF_1:22;
         consider q such that
         A32: a,b // p,q & a,p // b,q by DIRAF:47;
         A33: p,q // a,b & p,a // q,b by A32,AFF_1:13;
           p,q // a,b & LIN a,b,a by A32,AFF_1:13,16;
        hence f.a=b by A15,A31,A32,A33;
       end;
   hence thesis by A30;
  end;

theorem
Th9: AFP satisfies_des implies ex f st f is_Tr & f.a=b
  proof assume A1: AFP satisfies_des;
       a=b implies thesis by Th7;
   hence thesis by A1,Lm12;
  end;

theorem
   (for a,b ex f st f is_Tr & f.a=b) implies AFP satisfies_des
  proof assume A1: for a,b ex f st f is_Tr & f.a=b;
     now let a,a',b,c,b',c';
       assume A2: not LIN a,a',b & not LIN a,a',c &
       a,a' // b,b' & a,a' // c,c' & a,b // a',b' & a,c // a',c';
       consider f such that A3: f is_Tr and A4: f.a=a' by A1;
       A5: b'=f.b by A2,A3,A4,Th5; A6: c'=f.c by A2,A3,A4,Th5;
         f is_Dil by A3,TRANSGEO:def 11;
       hence b,c // b',c' by A5,A6,TRANSGEO:85; end;
      hence thesis by Th6;
  end;

theorem
Th11: f is_Tr & g is_Tr & not LIN a,f.a,g.a implies f*g=g*f
  proof assume A1: f is_Tr & g is_Tr; assume A2: not LIN a,f.a,g.a;
    A3: f is_Dil & g is_Dil by A1,TRANSGEO:def 11;
    then A4: a,f.a // g.a,g.(f.a) by TRANSGEO:85;
      a,g.a // f.a,g.(f.a) by A1,A3,TRANSGEO:100;
    then f.(g.a)=g.(f.a) by A1,A2,A4,Th5;
    then (f*g).a=g.(f.a) by FUNCT_2:70;
    then A5: (f*g).a=(g*f).a by FUNCT_2:70;
      f*g is_Tr & g*f is_Tr by A1,TRANSGEO:105;
   hence thesis by A5,TRANSGEO:103;
  end;

theorem
Th12: AFP satisfies_des & f is_Tr & g is_Tr implies f*g=g*f
  proof assume that A1: AFP satisfies_des and
    A2: f is_Tr and A3: g is_Tr; A4: g is_Dil by A3,TRANSGEO:def 11;
      now assume that A5: f<>id the carrier of AFP and
    A6: g<>id the carrier of AFP; consider a;
      A7: a<>f.a by A2,A5,TRANSGEO:def 11; A8: a<>g.a by A3,A6,TRANSGEO:def 11;
        now assume A9: LIN a,f.a,g.a; consider b such that
        A10: not LIN a,f.a,b by A7,AFF_1:22; consider h such that
        A11: h is_Tr and A12: h.a=b by A1,Th9;
           not LIN a,f.a,h.(g.a)
          proof assume LIN a,f.a,h.(g.a);
            then A13: LIN a,f.a,h.(g.a) & LIN a,f.a,a by AFF_1:16;

            A14: not LIN a,g.a,b
              proof assume LIN a,g.a,b;
                then LIN a,g.a,b & LIN a,g.a,f.a & LIN a,g.a,a
                                               by A9,AFF_1:15,16;
               hence contradiction by A8,A10,AFF_1:17;
              end;
            then (g*h).a=(h*g).a by A3,A11,A12,Th11;
            then (g*h).a=h.(g.a) by FUNCT_2:70;
            then A15: g.b=h.(g.a) by A12,FUNCT_2:70;
              a,g.a // b,g.b & a,b // g.a,g.b by A3,A4,TRANSGEO:85,100;
            then not LIN g.a,a,h.(g.a) by A14,A15,Lm5;
           hence contradiction by A7,A9,A13,AFF_1:17;
          end;
        then A16:
 h*g is_Tr & not LIN a,f.a,(h*g).a by A3,A11,FUNCT_2:70,TRANSGEO:105;

          h*(f*g)=(h*f)*g by RELAT_1:55 .=(f*h)*g by A2,A10,A11,A12,Th11
        .=f*(h*g) by RELAT_1:55 .=(h*g)*f by A2,A16,Th11
        .=h*(g*f) by RELAT_1:55;
       hence thesis by TRANSGEO:13;
      end;
     hence thesis by A2,A3,Th11;
    end;
   hence thesis by TRANSGEO:11;
  end;

theorem
Th13: f is_Tr & g is_Tr & p,f.p // p,g.p implies p,f.p // p,(f*g).p
  proof assume that A1: f is_Tr and A2: g is_Tr and
                                    A3: p,f.p // p,g.p;
    A4: f is_Dil by A1,TRANSGEO:def 11;
    A5: now assume g=id the carrier of AFP; then f*g=f by FUNCT_2:23;
         hence thesis by AFF_1:11;
        end;
      now assume g<>id the carrier of AFP; then A6: g.p<>p by A2,TRANSGEO:def
11
;
        p,g.p // f.p,f.(g.p) by A4,TRANSGEO:85;
      then p,f.p // f.p,f.(g.p) by A3,A6,AFF_1:14;
      then f.p,p // f.p,f.(g.p) by AFF_1:13;
      then LIN f.p,p,f.(g.p) by AFF_1:def 1;
      then LIN p,f.p,f.(g.p) by AFF_1:15;
      then p,f.p // p,f.(g.p) by AFF_1:def 1;
     hence thesis by FUNCT_2:70;
    end;
   hence thesis by A5;
  end;

theorem
   AFP satisfies_Fano & AFP satisfies_des & f is_Tr
                                 implies ex g st g is_Tr & g*g=f
  proof assume that A1: AFP satisfies_Fano & AFP satisfies_des
                and A2: f is_Tr;
    A3: now assume A4: f=id the carrier of AFP; set g=id the carrier of AFP;
          A5: g is_Tr by TRANSGEO:99;
            g*g=id the carrier of AFP by FUNCT_2:23;
        hence thesis by A4,A5;
        end;
      now assume A6: f<>id the carrier of AFP; consider a;
      set b=f.a; a<>b by A2,A6,TRANSGEO:def 11;
      then consider c such that A7: not LIN a,b,c by AFF_1:22;
      A8: not LIN c,a,b & not LIN c,b,a by A7,AFF_1:15;
      consider d such that
            A9: c,b // a,d & c,a // b,d by DIRAF:47;
      consider p such that
            A10: LIN b,a,p and A11: LIN c,d,p by A1,A8,A9,Th4;
      consider h such that A12: h is_Tr and A13: h.c = a by A1,Th9;
      A14: h.b=d by A8,A9,A12,A13,Th5;
      consider f1 being Permutation of the carrier of AFP such that
                    A15: f1 is_Tr and A16: f1.p=a by A1,Th9;
      consider f2 being Permutation of the carrier of AFP such that
                    A17: f2 is_Tr and A18: f2.p=b by A1,Th9;
      consider f3 being Permutation of the carrier of AFP such that
                    A19: f3 is_Tr and A20: f3.p=c by A1,Th9;
      consider f4 being Permutation of the carrier of AFP such that
                    A21: f4 is_Tr and A22: f4.p=d by A1,Th9;
      A23: (f2)" is_Tr by A17,TRANSGEO:104;
      A24: f1*f2=f4*f3
        proof f1.((f3)".c)=f1.p by A20,TRANSGEO:4;
          then A25: (f1*(f3)").c = a by A16,FUNCT_2:70;
            (f3)" is_Tr by A19,TRANSGEO:104;
          then f1*(f3)" is_Tr by A15,TRANSGEO:105;
          then A26: f1*(f3)"=h by A12,A13,A25,TRANSGEO:103;
            f4.((f2)".b)=f4.p by A18,TRANSGEO:4;
          then A27: (f4*f2").b=d by A22,FUNCT_2:70;
            f4*f2" is_Tr by A21,A23,TRANSGEO:105;
          then f1*f3"=f4*f2" by A12,A14,A26,A27,TRANSGEO:103;
          then f1*(f3"*f3)=(f4*f2")*f3 by RELAT_1:55;
          then f1*(id the carrier of AFP)=(f4*f2")*f3 by FUNCT_2:88;
          then f1=(f4*f2")*f3 by FUNCT_2:23
                .=f4*(f2"*f3) by RELAT_1:55
                .=f4*(f3*f2") by A1,A19,A23,Th12
                .=(f4*f3)*f2" by RELAT_1:55;
          then f1*f2=(f4*f3)*(f2"*f2) by RELAT_1:55
                      .=(f4*f3)*(id the carrier of AFP) by FUNCT_2:88
                      .=f4*f3 by FUNCT_2:23;
         hence f1*f2=f4*f3;
        end;
A28:      LIN p,c,d by A11,AFF_1:15;
      then A29: p,c // p,d by AFF_1:def 1;
        p,f3.p // p,f4.p by A20,A22,A28,AFF_1:def 1;
      then p,c // p,(f3*f4).p by A19,A20,A21,Th13;
      then A30: p,c // p,(f1*f2).p by A1,A19,A21,A24,Th12;
   LIN p,a,b by A10,AFF_1:15;
      then p,f1.p // p,f2.p by A16,A18,AFF_1:def 1;
      then A31: p,a // p,(f1*f2).p by A15,A16,A17,Th13;
        now assume p,c // p,a; then LIN p,c,a by AFF_1:def 1;
        then LIN p,a,c & LIN p,a,a & LIN p,a,b by A10,AFF_1:15,16;
        then p=a by A7,AFF_1:17;
        then a,c // c,b or a=d by A9,A29,AFF_1:14;
        then c,a // c,b or a=d by AFF_1:13;
        then LIN c,a,b or a=d by AFF_1:def 1;
        then a,c // a,b by A7,A9,AFF_1:13,15;
        then LIN a,c,b by AFF_1:def 1;
       hence contradiction by A7,AFF_1:15;
      end;
      then p=(f1*f2).p & f1*f2 is_Tr by A15,A17,A30,A31,AFF_1:14,TRANSGEO:105
;
      then f1"*(f1*f2)=f1"*(id the carrier of AFP) by TRANSGEO:def 11;
      then (f1"*f1)*f2=f1"*(id the carrier of AFP) by RELAT_1:55;
      then (id the carrier of AFP)*f2=f1"*(id the carrier of AFP)
       by FUNCT_2:88;
      then f2=f1"*(id the carrier of AFP) by FUNCT_2:23;
      then (f2*f2).a=(f2*f1").a by FUNCT_2:23 .=f2.(f1".a) by FUNCT_2:70
      .=b by A16,A18,TRANSGEO:4;
      then (f2*f2).a=f.a & f2*f2 is_Tr by A17,TRANSGEO:105;
      then f2*f2=f by A2,TRANSGEO:103;
     hence thesis by A17;
    end;
   hence thesis by A3;
  end;

theorem
Th15: AFP satisfies_Fano &
  f is_Tr & f*f=id the carrier of AFP implies f=id the carrier of AFP
  proof assume that A1: AFP satisfies_Fano and
   A2: f is_Tr and A3: f*f=id the carrier of AFP;
   consider a;
   assume f<>id the carrier of AFP;
    then a<>f.a by A2,TRANSGEO:def 11; then consider b such that
   A4: not LIN a,f.a,b by AFF_1:22;
   A5: f is_Dil by A2,TRANSGEO:def 11;
   then f.b,a // f.(f.b),f.a by TRANSGEO:85;
   then f.b,a // (f*f).b,f.a by FUNCT_2:70;
   then f.b,a // b,f.a by A3,FUNCT_1:35;
   then a,b // f.a,f.b & a,f.a // b,f.b & a,f.b // f.a,b
                          by A2,A5,AFF_1:13,TRANSGEO:85,100;
   hence contradiction by A1,A4,Def1;
  end;

theorem
   AFP satisfies_des & AFP satisfies_Fano &
  g is_Tr & f1 is_Tr & f2 is_Tr & g=f1*f1 & g=f2*f2 implies f1=f2
  proof assume that A1: AFP satisfies_des & AFP satisfies_Fano and
       g is_Tr and A2: f1 is_Tr and
    A3: f2 is_Tr and A4: g=f1*f1 and A5: g=f2*f2;
    set h=f2"*f1;
    A6: f2" is_Tr by A3,TRANSGEO:104;
    then A7: h is_Tr by A2,TRANSGEO:105;
      h*h=f2"*(f1*(f2"*f1)) by RELAT_1:55
    .=f2"*((f1*f2")*f1) by RELAT_1:55
    .=f2"*((f2"*f1)*f1) by A1,A2,A6,Th12
    .=f2"*(f2"*(f1*f1)) by RELAT_1:55
    .=(f2"*f2")*(f1*f1) by RELAT_1:55
    .=g"*g by A4,A5,FUNCT_1:66 .=id the carrier of AFP by FUNCT_2:88;
    then f2"*f1=id the carrier of AFP by A1,A7,Th15;
    then f2"*f1=f2"*f2 by FUNCT_2:88;
   hence f1=f2 by TRANSGEO:13;
  end;

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