
theorem Th114:
  for G1 being _Graph, G2 being removeDParallelEdges of G1
  for v1 being Vertex of G1, v2 being Vertex of G2
  st v1 = v2 & v1 is endvertex holds v2 is endvertex
proof
  let G1 be _Graph, G2 be removeDParallelEdges of G1;
  let v1 be Vertex of G1, v2 be Vertex of G2;
  assume A1: v1 = v2 & v1 is endvertex;
  then A2: v2 is endvertex or v2 is isolated by GLIB_000:84;
  v1 is non isolated by A1;
  hence v2 is endvertex by A1, A2, Th112;
end;
