proposition: Lemma isOpen_and : ∏ A B : T → hProp, isOpen A → isOpen B → isOpen (λ x : T, A x ∧ B x).
proof: Proof. apply isSetOfOpen_finite_intersection_and. intros P Hp. apply isOpen_finite_intersection. apply Hp. Qed.
imports: UniMath.Foundations.All UniMath.MoreFoundations.All UniMath.Topology.Filters UniMath.Algebra.Groups UniMath.Algebra.DivisionRig UniMath.Algebra.ConstructiveStructures