reserve SAS for Semi_Affine_Space;
reserve a,a9,a1,a2,a3,a4,b,b9,c,c9,d,d9,d1,d2,o,p,p1,p2,q,r,r1,r2,s,x, y,t,z
  for Element of SAS;

theorem Th102:
  ex x,y,z st x<>y & y<>z & z<>x
proof
  consider x,y,z such that
A1: not x,y // x,z by Def1;
  take x,y,z;
  thus thesis by A1,Def1,Th1,Th3;
end;
