
theorem
  for G1, G2 being _Graph
  holds [{},{}] is empty one-to-one Dcontinuous PGraphMapping of G1, G2
proof
  let G1, G2 be _Graph;
  reconsider F = [{},{}] as PGraphMapping of G1, G2 by Lm3;
  A1: F is empty;
  thus thesis by A1;
end;
