
theorem Th48:
  for G1, G2 being non-Dmulti _Graph, f being directed PVertexMapping of G1, G2
  st f is Disomorphism holds DPVM2PGM(f) is Disomorphism
proof
  let G1, G2 be non-Dmulti _Graph, f be directed PVertexMapping of G1, G2;
  assume f is Disomorphism;
  then DPVM2PGM(f) is total one-to-one onto Dcontinuous
    by Th33, Th35, Th37, Th41;
  hence thesis;
end;
