reserve G, G1, G2 for _Graph, H for Subgraph of G;

theorem
  for G3 being removeLoops of G1, G4 being removeLoops of G2
  st G4 is G3-isomorphic holds G1.allForests(),G2.allForests() are_isomorphic
proof
  let G3 be removeLoops of G1, G4 be removeLoops of G2;
  G1.allForests() = G3.allForests() & G2.allForests()=G4.allForests() by Th87;
  hence thesis by Th94;
end;
