fact: Definition neighborhood (x : T) : (T → hProp) → hProp := λ P : T → hProp, ∃ O : Open, O x × (∏ y : T, O y → P y).
imports: UniMath.Foundations.All UniMath.MoreFoundations.All UniMath.Topology.Filters UniMath.Algebra.Groups UniMath.Algebra.DivisionRig UniMath.Algebra.ConstructiveStructures