reserve x,y for set;
reserve X for non empty set;
reserve a,b,c,d for Element of X;
reserve S for OAffinSpace;
reserve a,b,c,d,p,q,r,x,y,z,t,u,w for Element of S;

theorem Th36:
  ex x,y,z st not x,y,z are_collinear
proof
  consider x,y,z such that
A1: not x,y '||' x,z by Th24;
  not x,y,z are_collinear by A1;
  hence thesis;
end;
