for f being non trivial special unfolded standard FinSequence of (TOP-REAL 2) st ( ( f /. 1 <> W-min (L~ f) & f /. (len f) <> W-min (L~ f) ) or ( f /. 1 <> W-max (L~ f) & f /. (len f) <> W-max (L~ f) ) ) holds
W-min (L~ f) <> W-max (L~ f)