proposition: Lemma isNeighborhood_isFilter {X : hSet} N : isNeighborhood N -> ∏ x : X, isFilter (N x).
proof: Proof. intros Hn x. split. - apply isNeighborhood_isPreFilter, Hn. - intros A Fa. apply hinhpr. exists x. apply ((pr1 (pr2 (pr2 (pr2 Hn)))) _ _ Fa). Qed.
imports: UniMath.Foundations.All UniMath.MoreFoundations.All UniMath.Topology.Filters UniMath.Algebra.Groups UniMath.Algebra.DivisionRig UniMath.Algebra.ConstructiveStructures