proposition: Lemma leU2 x y z t : x <= z -> y <= t -> x `|` y <= z `|` t.
proof: Proof. exact: (@leI2 _ L^d). Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(path fintype tuple bigop finset div prime finfun) mathcomp(finset)