
theorem
  for G1, G2 being _Graph, F being one-to-one PGraphMapping of G1, G2,
    H being Subgraph of G2 holds (H |` F)" = F" | H
proof
  let G1, G2 be _Graph, F be one-to-one PGraphMapping of G1, G2;
  let H be Subgraph of G2;
  (F"|H)" = H |` ((F")") by Th82;
  then ((F"|H)")" = (H |` F)" by Th70;
  hence thesis by Th70;
end;
