theorem Th179:
  for G2 being reverseEdgeDirections of G1, E
  holds G1 is finite-tcolorable iff G2 is finite-tcolorable
proof
  let G2 be reverseEdgeDirections of G1, E;
  hereby
    assume G1 is finite-tcolorable;
    then consider n such that
      A1: G1 is n-tcolorable;
    G2 is n-tcolorable by A1, Th168;
    hence G2 is finite-tcolorable;
  end;
  assume G2 is finite-tcolorable;
  then consider n such that
    A2: G2 is n-tcolorable;
  thus G1 is finite-tcolorable by A2, Def12, Th168;
end;
