reserve E,V for set, G,G1,G2 for _Graph, c,c1,c2 for Cardinal, n for Nat;
reserve f for VColoring of G;
reserve g for EColoring of G;

theorem
  for H being Subgraph of G holds H.eChromaticNum() c= G.eChromaticNum()
proof
  let H be Subgraph of G;
  G is G.eChromaticNum()-ecolorable by Lm14;
  hence thesis by Lm15;
end;
