proposition: Lemma fpowersetI A B : fpowerset (A `&` B) = fpowerset A `&` fpowerset B.
proof: Proof. by apply/fsetP=> X; rewrite inE !fpowersetE fsubsetI. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrnat eqtype ssrfun seq) mathcomp(choice path finset finfun fintype bigop)