theorem
  f is collineation & g is collineation implies f" is collineation & f*g
  is collineation & id the carrier of AFS is collineation
proof
  assume f is_automorphism_of the CONGR of AFS & g is_automorphism_of the
  CONGR of AFS;
  hence f" is_automorphism_of the CONGR of AFS & f*g is_automorphism_of the
  CONGR of AFS by Th17,Th18;
  thus id the carrier of AFS is_automorphism_of the CONGR of AFS;
end;
