reserve AS for AffinSpace;
reserve a,a9,b,b9,c,d,o,p,q,r,s,x,y,z,t,u,w for Element of AS;

theorem Th11:
  ex x,y,z st not LIN x,y,z
proof
  consider x,y,z such that
A1: not x,y // x,z by DIRAF:40;
  not LIN x,y,z by A1;
  hence thesis;
end;
