Section unitOrd.
Let ordtt (x y : unit ) := false.
(* in a sorted list, the last element is maximal *)
(* and the maximal element is last *)

Lemma seq_last_mono (A : ordType) (s1 s2 : seq A) x :
path oleq x s1 -> path oleq x s2 ->
{subset s1 <= s2} ->
oleq (last x s1) (last x s2).