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