proposition: Lemma lt_def x y: (x < y) = (y != x) && (x <= y).
proof: Proof. exact: lt_def. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(path fintype tuple bigop finset div prime finfun) mathcomp(finset)