proposition: Lemma eq_le x y: (x == y) = (x <= y <= x).
proof: Proof. by apply/eqP/idP => [->|/le_anti]; rewrite ?lexx. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(path fintype tuple bigop finset div prime finfun) mathcomp(finset)