proposition: Lemma filterintersection_imply : isfilter_imply filterintersection.
proof: Proof. intros A B H Ha F Hf. apply (Himp F Hf A). - apply H. - simple refine (Ha _ _). exact Hf. Qed.
imports: UniMath.Foundations.Preamble UniMath.MoreFoundations.Tactics UniMath.Topology.Prelim UniMath.MoreFoundations.PartA