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