
theorem
  for G1, G2 being _trivial loopless _Graph
  holds G2 is G1-Disomorphic G1-isomorphic
proof
  let G1, G2 be _trivial loopless _Graph;
  set F = the non empty PGraphMapping of G1, G2;
  F is directed isomorphism;
  hence G2 is G1-Disomorphic;
  hence G2 is G1-isomorphic;
end;
