Zulip Chat Archive

Stream: Is there code for X?

Topic: pushforward of product topology is product topology


Kevin Buzzard (Aug 24 2024 at 23:28):

Do we have anything like

import Mathlib.Topology.Constructions

example {ι κ : Type*} (e : ι  κ) (X : Type*) [TopologicalSpace X] :
    TopologicalSpace.coinduced (fun f  f  e : (κ  X)  (ι  X)) Pi.topologicalSpace =
    Pi.topologicalSpace := by
  sorry

Mathematically I'm asking that the product topologies on XmX^m and XnX^n coincide given a bijection m=nm=n. The map (κ → X) → (ι → X) can be beefed up to can equiv with Equiv.piCongrLeft' if necessary. I tried doing this with some lattice manipulations but didn't get anywhere, and breaking it up into <= and >= didn't look like much fun either.

Yury G. Kudryashov (Aug 24 2024 at 23:58):

We have docs#Homeomorph.piCongrLeft

Kevin Buzzard (Aug 25 2024 at 07:42):

Perfect, thanks!


Last updated: May 02 2025 at 03:31 UTC