
theorem Th74:
  for G1, G2 being _Graph, F be one-to-one PGraphMapping of G1, G2
  st F is total Dcontinuous holds F" is Dcontinuous
proof
  let G1, G2 be _Graph, F be one-to-one PGraphMapping of G1, G2;
  assume A1: F is total Dcontinuous;
  then F" is onto by FUNCT_1:33;
  hence F" is Dcontinuous by A1;
end;
