proposition: Lemma comparable_contra_lt_le x y z t : z >=< t -> (t < z -> y <= x) -> (x < y -> z <= t).
proof: Proof. by do 2![case: comparableP => //= ?]. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(path fintype tuple bigop finset div prime finfun) mathcomp(finset)