proposition: Lemma fsubsetIidr A B : (B `<=` A `&` B) = (B `<=` A).
proof: Proof. by rewrite fsetIC fsubsetIidl. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrnat eqtype ssrfun seq) mathcomp(choice path finset finfun fintype bigop)