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[Merged by Bors] - feat(number_theory): define number fields, function fields and their rings of integers #8701

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@Vierkantor Vierkantor commented Aug 16, 2021

@Vierkantor Vierkantor added awaiting-review The author would like community review of the PR blocked-by-other-PR This PR depends on another PR which is still in the queue. A bot manages this label via PR comment. labels Aug 16, 2021
Vierkantor added a commit that referenced this pull request Aug 24, 2021
Let `L` be a finite separable extension of `K = Frac(A)`, where `A` is a Dedekind domain. Then `integral_closure A L` is also a Dedekind domain.

In combination with the definitions of #8701, we can conclude that rings of integers are Dedekind domains.
Vierkantor added a commit that referenced this pull request Aug 24, 2021
Let `L` be a finite separable extension of `K = Frac(A)`, where `A` is a Dedekind domain. Then `integral_closure A L` is also a Dedekind domain.

In combination with the definitions of #8701, we can conclude that rings of integers are Dedekind domains.
Vierkantor added a commit that referenced this pull request Aug 24, 2021
Let `L` be a finite separable extension of `K = Frac(A)`, where `A` is a Dedekind domain. Then `integral_closure A L` is also a Dedekind domain.

In combination with the definitions of #8701, we can conclude that rings of integers are Dedekind domains.
@github-actions github-actions bot removed the blocked-by-other-PR This PR depends on another PR which is still in the queue. A bot manages this label via PR comment. label Aug 25, 2021
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🎉 Great news! Looks like all the dependencies have been resolved:

💡 To add or remove a dependency please update this issue/PR description.

Brought to you by Dependent Issues (:robot: ). Happy coding!

@github-actions github-actions bot added the merge-conflict Please `git merge origin/master` then a bot will remove this label. label Aug 25, 2021
@github-actions github-actions bot removed the merge-conflict Please `git merge origin/master` then a bot will remove this label. label Aug 26, 2021
Vierkantor added a commit that referenced this pull request Aug 26, 2021
The typeclass `is_integral_closure A R B` states `A` is the integral closure of `R` in `B`, i.e. that an element of `B` is integral over `R` iff it is an element of (the image of) `A`.
We also show that any integral extension of `R` contained in `B` is contained in `A`, and the integral closure is unique up to isomorphism.

This was suggested in the review of #8701, in order to define a characteristic predicate for rings of integers.
bors bot pushed a commit that referenced this pull request Aug 27, 2021
The typeclass `is_integral_closure A R B` states `A` is the integral closure of `R` in `B`, i.e. that an element of `B` is integral over `R` iff it is an element of (the image of) `A`.
We also show that any integral extension of `R` contained in `B` is contained in `A`, and the integral closure is unique up to isomorphism.

This was suggested in the review of #8701, in order to define a characteristic predicate for rings of integers.



Co-authored-by: Anne Baanen <Vierkantor@users.noreply.github.com>
Vierkantor added a commit that referenced this pull request Aug 27, 2021
Let `L` be a finite separable extension of `K = Frac(A)`, where `A` is a Dedekind domain. Then `integral_closure A L` is also a Dedekind domain.

In combination with the definitions of #8701, we can conclude that rings of integers are Dedekind domains.
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@jcommelin jcommelin 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 Aug 28, 2021
@Vierkantor Vierkantor 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 Sep 1, 2021
Vierkantor added a commit that referenced this pull request Sep 1, 2021
Let `L` be a finite separable extension of `K = Frac(A)`, where `A` is a Dedekind domain. Then `integral_closure A L` is also a Dedekind domain.

In combination with the definitions of #8701, we can conclude that rings of integers are Dedekind domains.
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Thanks 🎉

bors d+

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bors bot commented Sep 1, 2021

✌️ Vierkantor 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 Sep 1, 2021
Comment on lines 56 to 58
-- The `is_number_field K` hypothesis is not used but is required for
-- this definition to make sense.
@[nolint unused_arguments]
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Shouldn't we leave it out anyway? It would be sufficient to assume it for lemmas, right?

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I'm just a bit wary of someone having open function_field number_field somewhere, trying to get the ring of integers of a function field, and receiving the integral closure of instead. Complaining about a missing instance would prevent that issue. But I guess they will notice the issue as soon as they try to prove anything with it.

bors bot pushed a commit that referenced this pull request Sep 2, 2021
…DD (#8847)

Let `L` be a finite separable extension of `K = Frac(A)`, where `A` is a Dedekind domain. Then any `is_integral_closure C A L` is also a Dedekind domain, in particular for `C := integral_closure A L`.

In combination with the definitions of #8701, we can conclude that rings of integers are Dedekind domains.
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bors merge

@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 Sep 2, 2021
bors bot pushed a commit that referenced this pull request Sep 2, 2021
…rings of integers (#8701)

Co-Authored-By: Ashvni <ashvni.n@gmail.com>



Co-authored-by: Anne Baanen <Vierkantor@users.noreply.github.com>
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bors bot commented Sep 2, 2021

Pull request successfully merged into master.

Build succeeded:

@bors bors bot changed the title feat(number_theory): define number fields, function fields and their rings of integers [Merged by Bors] - feat(number_theory): define number fields, function fields and their rings of integers Sep 2, 2021
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@bors bors bot deleted the is_number_field branch September 2, 2021 16:40
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