
theorem Th143:
  for G1 being _Graph, G2 being G1-isomorphic _Graph, E1, E2 being set
  for G3 being reverseEdgeDirections of G1, E1
  for G4 being reverseEdgeDirections of G2, E2
  holds G4 is G3-isomorphic
proof
  let G1 be _Graph, G2 be G1-isomorphic _Graph, E1, E2 be set;
  let G3 be reverseEdgeDirections of G1, E1;
  let G4 be reverseEdgeDirections of G2, E2;
  consider F0 being PGraphMapping of G1, G2 such that
    A1: F0 is isomorphism by Def23;
  consider F being PGraphMapping of G3, G4 such that
    F = F0 and
    F0 is weak_SG-embedding implies F is weak_SG-embedding and
    F0 is strong_SG-embedding implies F is strong_SG-embedding and
    A2: F0 is isomorphism implies F is isomorphism by Th142;
  thus thesis by A1, A2;
end;
