Skip to content
This repository was archived by the owner on Jul 24, 2024. It is now read-only.

[Merged by Bors] - feat(analysis/locally_convex): first countable topologies from countable families of seminorms#16595

Closed
mcdoll wants to merge 4 commits intomasterfrom
mcdoll/first_countable_seminorms
Closed

[Merged by Bors] - feat(analysis/locally_convex): first countable topologies from countable families of seminorms#16595
mcdoll wants to merge 4 commits intomasterfrom
mcdoll/first_countable_seminorms

Conversation

@mcdoll
Copy link
Copy Markdown
Member

@mcdoll mcdoll commented Sep 22, 2022

This PR proves that if the topology is induced by a countable family of seminorms, then it is first countable.


Open in Gitpod

@mcdoll mcdoll added awaiting-review The author would like community review of the PR t-topology Topological spaces, uniform spaces, metric spaces, filters t-analysis Analysis (normed *, calculus) labels Sep 22, 2022
Comment on lines +534 to +536
lemma with_seminorms.has_countable_basis (hp : with_seminorms p) :
(𝓝 (0 : E)).has_countable_basis (λ _, true)
(λ i : finset ι × ℕ, ball (i.fst.sup p) 0 (i.snd + 1)⁻¹) :=
Copy link
Copy Markdown
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Do you care about the specific basis or do you only use that for showing that this filter is countably generated. If the latter, you could simply use with_seminorms_iff_nhds_eq_infi and then apply filter.comap.is_countably_generated and filter.infi.is_countably_generated

Copy link
Copy Markdown
Member Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I am not entirely certain that the first lemma is not used anywhere, but it does not feel to useful.

@ADedecker ADedecker added awaiting-author A reviewer has asked the author a question or requested changes and removed awaiting-review The author would like community review of the PR labels Oct 1, 2022
@mcdoll mcdoll added awaiting-review The author would like community review of the PR and removed awaiting-author A reviewer has asked the author a question or requested changes labels Oct 1, 2022
@ADedecker ADedecker self-assigned this Oct 1, 2022
@ADedecker ADedecker added awaiting-author A reviewer has asked the author a question or requested changes and removed awaiting-review The author would like community review of the PR labels Oct 2, 2022
Co-authored-by: Anatole Dedecker <anatolededecker@gmail.com>
@mcdoll mcdoll added awaiting-review The author would like community review of the PR and removed awaiting-author A reviewer has asked the author a question or requested changes labels Oct 2, 2022
Copy link
Copy Markdown
Member

@ADedecker ADedecker left a comment

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Thanks!

maintainer merge

@github-actions
Copy link
Copy Markdown

github-actions bot commented Oct 2, 2022

🚀 Pull request has been placed on the maintainer queue by ADedecker.

@kmill
Copy link
Copy Markdown
Collaborator

kmill commented Oct 2, 2022

Thanks!

bors r+

@github-actions github-actions bot added ready-to-merge All that is left is for bors to build and merge this PR. (Remember you need to say `bors r+`.) and removed awaiting-review The author would like community review of the PR labels Oct 2, 2022
bors bot pushed a commit that referenced this pull request Oct 2, 2022
…ble families of seminorms (#16595)

This PR proves that if the topology is induced by a countable family of seminorms, then it is first countable.
@bors
Copy link
Copy Markdown

bors bot commented Oct 2, 2022

Pull request successfully merged into master.

Build succeeded:

@bors bors bot changed the title feat(analysis/locally_convex): first countable topologies from countable families of seminorms [Merged by Bors] - feat(analysis/locally_convex): first countable topologies from countable families of seminorms Oct 2, 2022
@bors bors bot closed this Oct 2, 2022
@bors bors bot deleted the mcdoll/first_countable_seminorms branch October 2, 2022 13:30
Sign up for free to subscribe to this conversation on GitHub. Already have an account? Sign in.

Labels

ready-to-merge All that is left is for bors to build and merge this PR. (Remember you need to say `bors r+`.) t-analysis Analysis (normed *, calculus) t-topology Topological spaces, uniform spaces, metric spaces, filters

Projects

None yet

Development

Successfully merging this pull request may close these issues.

3 participants