
theorem Th34:
  for P being pcs-Str, p, q being Element of P
  for p9, q9 being Element of pcs-reverse(P) st p = p9 & q = q9 holds
  p (--) q implies not p9 (--) q9
proof
  let P be pcs-Str, p, q be Element of P;
  set R = pcs-reverse(P);
  let p9, q9 be Element of R such that
A1: p = p9 and
A2: q = q9;
A3: the ToleranceRel of R = (the ToleranceRel of P)` by Def40;
  assume [p,q] in the ToleranceRel of P;
  hence not [p9,q9] in the ToleranceRel of R by A1,A2,A3,XBOOLE_0:def 5;
end;
