proposition: Lemma ltEseqlexi s1 s2 : s1 < s2 = if s2 isn't x2 :: s2' then false else if s1 isn't x1 :: s1' then true else (x1 <= x2) && ((x1 >= x2) ==> (s1' < s2' :> seq T)).
proof: Proof. by case: s1. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(path fintype tuple bigop finset div prime finfun) mathcomp(finset)