proposition: Lemma comparable_contra_le_lt 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)