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