Zulip Chat Archive

Stream: mathlib4

Topic: BoundedSpace <-> CompactSpace


Alex Meiburg (Sep 01 2025 at 16:15):

Should any / all of the four following theorems be instances in Mathlib?

import Mathlib

section r0space

variable {X : Type*} [TopologicalSpace X] [R0Space X]

instance R0Space.boundedSpace_of_compactSpace [CompactSpace X] : @BoundedSpace X (Bornology.relativelyCompact X) := by
  let := Bornology.relativelyCompact X
  constructor
  rw [Bornology.relativelyCompact.isBounded_iff, IsClosed.closure_eq (isClosed_univ)]
  exact CompactSpace.isCompact_univ

instance R0Space.compactSpace_of_boundedSpace [@BoundedSpace X (Bornology.relativelyCompact X)] : CompactSpace X := by
  let := Bornology.relativelyCompact X
  constructor
  rw [ IsClosed.closure_eq (isClosed_univ),  Bornology.relativelyCompact.isBounded_iff]
  exact BoundedSpace.bounded_univ

end r0space

section pseudometricspace

variable {X : Type*} [PseudoMetricSpace X]

instance PseudoMetricSpace.boundedSpace_of_compactSpace [CompactSpace X] : BoundedSpace X :=
  CompactSpace.isCompact_univ.isBounded

instance PseudoMetricSpace.compactSpace_of_boundedSpace [ProperSpace X] [BoundedSpace X] : CompactSpace X :=
  IsClosed.closure_eq (@isClosed_univ X _)  BoundedSpace.bounded_univ.isCompact_closure

end pseudometricspace

Alex Meiburg (Sep 01 2025 at 16:15):

Currently there's nothing under

#loogle BoundedSpace, CompactSpace


Last updated: Dec 20 2025 at 21:32 UTC