
theorem Th107:
  for G1 being _Graph, G2 being removeDParallelEdges of G1
  holds G1 is chordal iff G2 is chordal
proof
  let G1 be _Graph, G2 be removeDParallelEdges of G1;
  set G3 = the removeParallelEdges of G2;
  G3 is removeParallelEdges of G1 by Th95;
  then G1 is chordal iff G3 is chordal by Th106;
  hence thesis by Th106;
end;
