proposition: Lemma comparable_contra_ltn_lt m n x y : x >=< y -> (y <= x -> (n <= m)%N) -> ((m < n)%N -> x < y).
proof: Proof. by case: comparableP; case: ltngtP. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(path fintype tuple bigop finset div prime finfun) mathcomp(finset)