proposition: Lemma ltxi_cons x1 s1 x2 s2 : x1 :: s1 < x2 :: s2 :> seq T = (x1 <= x2) && ((x1 >= x2) ==> (s1 < s2)).
proof: Proof. by []. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(path fintype tuple bigop finset div prime finfun) mathcomp(finset)