proposition: Lemma eq_leRL x y z t : (x <= y -> z <= t) -> (y < x -> t < z) -> (z <= t) = (x <= y).
proof: Proof. by move=> *; symmetry; apply: eq_leLR. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(path fintype tuple bigop finset div prime finfun) mathcomp(finset)