proposition: Fact lt_def x y : lt x y = (y != x) && le x y.
proof: Proof. by rewrite le_def; case: eqVneq => //= ->; rewrite lt_irr. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(path fintype tuple bigop finset div prime finfun) mathcomp(finset)