proposition: Lemma le1x x : (\top <= x) = (x == \top).
proof: Proof. by rewrite le_eqVlt (le_gtF (lex1 _)) eq_sym; case: eqP. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(path fintype tuple bigop finset div prime finfun) mathcomp(finset)