
theorem Th10:
  for S, T being non empty RelStr, f being Function of S, T st f
  is isomorphic holds f/" is isomorphic
proof
  let S, T be non empty RelStr, f be Function of S, T;
  assume
A1: f is isomorphic;
  then (ex g being Function of T, S st g = f qua Function" & g is monotone )&
  rng f = the carrier of T by WAYBEL_0:66,def 38;
  hence thesis by A1,TOPS_2:def 4,WAYBEL_0:68;
end;
