theorem
  for v,e,w being object, G1 being addAdjVertex of G2,v,e,w
  holds G1.eChromaticNum() c= G2.eChromaticNum() +` 1
proof
  let v,e,w be object, G1 be addAdjVertex of G2,v,e,w;
  G2 is G2.eChromaticNum()-ecolorable by Lm14;
  hence thesis by Th107, Lm15;
end;
