proposition: Lemma topologysubtype_htrue : ∏ x : ∑ x : T, dom x, isfilter_htrue (topologysubtype x).
proof: Proof. intros x. apply hinhpr. exists (λ _, htrue). repeat split. now apply isOpen_htrue. Qed.
imports: UniMath.Foundations.All UniMath.MoreFoundations.All UniMath.Topology.Filters UniMath.Algebra.Groups UniMath.Algebra.DivisionRig UniMath.Algebra.ConstructiveStructures