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feat(topology/uniform_space/uniform_convergence_topology): bases for uniform structures of š”–-convergence

Open ADedecker opened this issue 3 years ago • 1 comments

By definition, the sets S(V) := {(f, g) | āˆ€ x, (f x, g x) ∈ V} for Vāˆˆš“¤ β form a basis for the uniformity of uniform convergence on α → β. We extend this result in the two following ways :

  • we show that it suffices to consider only the sets V in a basis of š“¤ β instead of all the entourages
  • we deduce a similar result for the uniformity of š”–-convergence for a directed š”– : in that case, a basis is given by the sets S'(A,V) := {(f, g) | āˆ€ x ∈ A, (f x, g x) ∈ V} for A āˆˆš”– and V in a basis of š“¤ β

  • [x] depends on: #14775
  • [ ] depends on: #14534

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ADedecker avatar Jun 16 '22 19:06 ADedecker

This PR/issue depends on:

  • ~~leanprover-community/mathlib#14775~~
  • ~~leanprover-community/mathlib#14534~~ By Dependent Issues (šŸ¤–). Happy coding!

bors d+

fpvandoorn avatar Sep 29 '22 11:09 fpvandoorn

:v: ADedecker can now approve this pull request. To approve and merge a pull request, simply reply with bors r+. More detailed instructions are available here.

bors[bot] avatar Sep 29 '22 11:09 bors[bot]

Yes I've thought about making a type alias before (it's written in the TODO section of the module docstring with a question mark), but I'm not sure there will be enough uses of this to justify making a type alias. But if you think we should do it I'm happy to take care of that in a future PR.

ADedecker avatar Sep 29 '22 13:09 ADedecker

I don't know how often these concepts are used. Feel free to leave it like this if you think it's rarely used.

fpvandoorn avatar Sep 29 '22 13:09 fpvandoorn

I'll ask on Zulip this evening. I would say it's not super annoying, but maybe I just got used to it.

ADedecker avatar Sep 29 '22 14:09 ADedecker

bors r+

ADedecker avatar Sep 29 '22 17:09 ADedecker

Pull request successfully merged into master.

Build succeeded:

bors[bot] avatar Sep 29 '22 21:09 bors[bot]