Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

[Merged by Bors] - feat(analysis/normed_space/finite_dimension): extending partially defined Lipschitz functions #11530

Closed
wants to merge 3 commits into from

Conversation

sgouezel
Copy link
Collaborator

Any Lipschitz function on a subset of a metric space, into a finite-dimensional real vector space, can be extended to a globally defined Lipschitz function (up to worsening slightly the Lipschitz constant).


Open in Gitpod

@sgouezel sgouezel added the awaiting-review The author would like community review of the PR label Jan 17, 2022
Copy link
Member

@hrmacbeth hrmacbeth left a comment

Choose a reason for hiding this comment

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

bors d+

lemma lipschitz_on_with.extend_pi [pseudo_metric_space α] [fintype ι]
{f : α → (ι → ℝ)} {s : set α} {K : ℝ≥0}
(hf : lipschitz_on_with K f s) :
∃ g : α → (ι → ℝ), lipschitz_with K g ∧ eq_on f g s :=
Copy link
Member

Choose a reason for hiding this comment

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

I believe this is also true for infinite ι with the l-infinity norm, with essentially the same proof, see section 2 here. Can you please mention this in the docstring? It might even be a "Good First Project"!

@bors
Copy link

bors bot commented Jan 20, 2022

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

@leanprover-community-bot-assistant leanprover-community-bot-assistant added delegated The PR author may merge after reviewing final suggestions. and removed awaiting-review The author would like community review of the PR labels Jan 20, 2022
@sgouezel
Copy link
Collaborator Author

bors r+

@github-actions github-actions bot added the ready-to-merge All that is left is for bors to build and merge this PR. (Remember you need to say `bors r+`.) label Jan 20, 2022
bors bot pushed a commit that referenced this pull request Jan 20, 2022
…ined Lipschitz functions (#11530)

Any Lipschitz function on a subset of a metric space, into a finite-dimensional real vector space, can be extended to a globally defined Lipschitz function (up to worsening slightly the Lipschitz constant).
@bors
Copy link

bors bot commented Jan 20, 2022

Pull request successfully merged into master.

Build succeeded:

@bors bors bot changed the title feat(analysis/normed_space/finite_dimension): extending partially defined Lipschitz functions [Merged by Bors] - feat(analysis/normed_space/finite_dimension): extending partially defined Lipschitz functions Jan 20, 2022
@bors bors bot closed this Jan 20, 2022
@bors bors bot deleted the lipschitz_extension branch January 20, 2022 08:31
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Labels
delegated The PR author may merge after reviewing final suggestions. ready-to-merge All that is left is for bors to build and merge this PR. (Remember you need to say `bors r+`.)
Projects
None yet
Development

Successfully merging this pull request may close these issues.

None yet

3 participants