
theorem Th60:
  for G1, G2 being _Graph, G3 being removeLoops of G1
  st G1 == G2 holds G3 is removeLoops of G2
proof
  let G1, G2 be _Graph, G3 be removeLoops of G1;
  assume A1: G1 == G2;
  then the_Vertices_of G1 = the_Vertices_of G2 &
    the_Edges_of G1 = the_Edges_of G2 & G1.loops() = G2.loops()
    by Th50, GLIB_000:def 34;
  hence thesis by A1, GLIB_000:95;
end;
