proposition: Fact join_leR {x y} : y <= (join x y).
proof: Proof. by have:= le_refl (join x y); rewrite joinP => /andP []. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(path fintype tuple bigop finset div prime finfun) mathcomp(finset)