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