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;
reserve t for TColoring of G;

theorem
  for G being loopless _Graph, H being Subgraph of G
  holds H.tChromaticNum() c= G.tChromaticNum()
proof
  let G be loopless _Graph, H be Subgraph of G;
  G is G.tChromaticNum()-tcolorable by Th186;
  hence thesis by Th189;
end;
