proposition: Lemma comparable_contra_leq_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)