proposition: Lemma joinIKC x y : (y `|` x) `&` y = y.
proof: Proof. by rewrite joinC joinIK. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(path fintype tuple bigop finset div prime finfun) mathcomp(finset)