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[Merged by Bors] - feat(field_theory/algebraic_closure): algebraic closure #3733

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@kckennylau kckennylau commented Aug 10, 2020

instance : is_alg_closed (algebraic_closure k) :=

TODO: Show that any algebraic extension embeds into any algebraically closed extension (via Zorn's lemma).


@kckennylau kckennylau added the awaiting-review The author would like community review of the PR label Aug 10, 2020
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ocfnash commented Aug 11, 2020

Delighted to see this. I was literally just looking for the definition of algebraically closed fields three days ago, when writing this. Looking forward to updating one this merges.

@Vierkantor Vierkantor self-requested a review August 11, 2020 10:15
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Looking forward to merging this PR. The structure looks good, I left some comments on the documentation. I didn't have time to look closely at style.

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@@ -321,6 +321,8 @@ begin
... ≤ v (a + s) : aux (a + s) (-s) (by rwa ←ideal.neg_mem_iff at h)
end

local attribute [-instance] classical.DLO
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Could you add a comment (linking to Zulip?) explaining why this instance is problematic here?

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done

@robertylewis robertylewis 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 11, 2020
Co-authored-by: Vierkantor <Vierkantor@users.noreply.github.com>
@kckennylau kckennylau added the awaiting-review The author would like community review of the PR label Aug 11, 2020
- `is_alg_closure k K` is the typeclass saying `K` is an algebraic closure of `k`.

- `algebraic_closure k` is an algebraic closure of `k` (in the same universe).

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Could you add a description of the construction you are using, and a bibliography reference if you followed a book or paper? There are many ways to prove this theorem and it would help to know which one you use.

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Done

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Style / indentation comments.

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@Vierkantor Vierkantor removed the awaiting-review The author would like community review of the PR label Aug 12, 2020
Co-authored-by: Vierkantor <Vierkantor@users.noreply.github.com>
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Thanks!

bors r+

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bors bot commented Aug 12, 2020

👎 Rejected by label

@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 Aug 12, 2020
@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 Aug 12, 2020
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bors r+

bors bot pushed a commit that referenced this pull request Aug 12, 2020
```lean
instance : is_alg_closed (algebraic_closure k) :=
```

TODO: Show that any algebraic extension embeds into any algebraically closed extension (via Zorn's lemma).



Co-authored-by: Patrick Massot <patrickmassot@free.fr>
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bors bot commented Aug 12, 2020

Pull request successfully merged into master.

Build succeeded:

@bors bors bot changed the title feat(field_theory/algebraic_closure): algebraic closure [Merged by Bors] - feat(field_theory/algebraic_closure): algebraic closure Aug 12, 2020
@bors bors bot closed this Aug 12, 2020
@bors bors bot deleted the kenny-alg-closure branch August 12, 2020 16:33
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5 participants