
theorem Th15:
  for L, M being non empty RelStr st L, M are_isomorphic & L is
  reflexive holds M is reflexive
proof
  let L, M be non empty RelStr such that
A1: L, M are_isomorphic and
A2: L is reflexive;
  let x be Element of M;
  M, L are_isomorphic by A1,WAYBEL_1:6;
  then consider f being Function of M, L such that
A3: f is isomorphic;
  reconsider fx = f.x as Element of L;
  fx <= fx by A2;
  hence thesis by A3,WAYBEL_0:66;
end;
