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(algebraic_geometry): Lift isomorphism of sheafed spaces to locally ringed spaces #8887

Closed
wants to merge 27 commits into from

Conversation

justus-springer
Copy link
Collaborator

@justus-springer justus-springer commented Aug 27, 2021

Adds the fact that an isomorphism of sheafed spaces can be lifted to an isomorphism of locally ringed spaces. The main ingredient is the fact that stalk maps of isomorphisms are again isomorphisms.

In particular, this implies that the forgetful functor LocallyRingedSpace ⥤ SheafedSpace CommRing reflects isomorphisms.


This PR will be used to lift the isomorphism restrict_top_iso from the level of presheafed spaces to the level of locally ringed spaces. This is needed to complete the redefinition of Schemes (see #8888).

Open in Gitpod

Copy link
Member

@jcommelin jcommelin left a comment

Choose a reason for hiding this comment

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

Thanks 🎉

bors d+

src/algebraic_geometry/stalks.lean Outdated Show resolved Hide resolved
src/algebraic_geometry/stalks.lean Outdated Show resolved Hide resolved
Comment on lines +106 to +108
Unfortunately, this equality is not well-formed, as their types are not _definitionally_ the same.
To get a proper congruence lemma, we therefore have to introduce these `eq_to_hom` arrows on
either side of the equality.
Copy link
Member

Choose a reason for hiding this comment

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

This is quite unfortunate. But I don't see a better solution atm.

Copy link
Collaborator Author

Choose a reason for hiding this comment

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

Yes, it took me some time to get used to all the eq_to_homs involved... But now I think it's not so bad after all.

@bors
Copy link

bors bot commented Aug 28, 2021

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

@github-actions github-actions bot 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 Aug 28, 2021
@justus-springer
Copy link
Collaborator Author

bors r+

bors bot pushed a commit that referenced this pull request Aug 29, 2021
…ly ringed spaces (#8887)

Adds the fact that an isomorphism of sheafed spaces can be lifted to an isomorphism of locally ringed spaces. The main ingredient is the fact that stalk maps of isomorphisms are again isomorphisms.

In particular, this implies that the forgetful functor `LocallyRingedSpace ⥤ SheafedSpace CommRing` reflects isomorphisms.



Co-authored-by: justus-springer <50165510+justus-springer@users.noreply.github.com>
@bors
Copy link

bors bot commented Aug 29, 2021

Pull request successfully merged into master.

Build succeeded:

@bors bors bot changed the title feat(algebraic_geometry): Lift isomorphism of sheafed spaces to locally ringed spaces [Merged by Bors] - feat(algebraic_geometry): Lift isomorphism of sheafed spaces to locally ringed spaces Aug 29, 2021
@bors bors bot closed this Aug 29, 2021
@bors bors bot deleted the locally_ringed_space_reflects_iso branch August 29, 2021 14:41
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.
Projects
None yet
Development

Successfully merging this pull request may close these issues.

None yet

2 participants