
theorem Th2:
  for P1,P2 being RelStr st the RelStr of P1 = the RelStr of P2 for
  X being set for a1 being Element of P1 for a2 being Element of P2 st a1 = a2
  holds (X is_<=_than a1 implies X is_<=_than a2) & (X is_>=_than a1 implies X
  is_>=_than a2)
by Th1;
