proposition: Lemma contra_not_le P z t : (t < z -> P) -> (~ P -> z <= t).
proof: Proof. exact: comparable_contra_not_le. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(path fintype tuple bigop finset div prime finfun) mathcomp(finset)