proposition: Lemma filterdom_notempty : isfilter_notempty filterdom.
proof: Proof. intros. intros A Fa. generalize (Hdom _ Fa). apply hinhfun. intros x. exists (pr1 x). apply (pr2 (pr2 x)), (pr1 (pr2 x)). Qed.
imports: UniMath.Foundations.Preamble UniMath.MoreFoundations.Tactics UniMath.Topology.Prelim UniMath.MoreFoundations.PartA