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[Merged by Bors] - feat : generalize PrimeSpectrum from Ring to Semiring #8763
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Changed proof to avoid a deterministic timeout
Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
Out of curiosity: Would you mind commenting a bit on the motivation for this PR? |
There are some papers about how the whole construction of Schemes work for general commutative semirings. In that papers, most of the details are omitted. I am trying to see if the proofs are more or less the same. As the changes in this case are minimum (just some results true for CommRing are not true for CommSemiring), I thought it would be nice to have it in mathlib4. The change in the AlgebraicGeometry.Properties is due to what it seems some inference (?) did not work. |
@XavierXarles Nice, that seems like an interesting project! Can you please update the PR title according to the guidelines? And I think it would be nice if you can debug a bit further why some proofs become longer. Is there a mathematical reason, or is it because some API for semirings is under developed? |
I am not sure to what proofs you refer as being longer. Do you mean the proof in AlgebraicGeometry.Properties of the instance? |
Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
(x : PrimeSpectrum S) (hx : IsClosed ({x} : Set (PrimeSpectrum S))) : | ||
IsClosed ({comap f x} : Set (PrimeSpectrum R)) := | ||
haveI : x.asIdeal.IsMaximal := (isClosed_singleton_iff_isMaximal x).1 hx | ||
(isClosed_singleton_iff_isMaximal _).2 (Ideal.comap_isMaximal_of_surjective f hf) |
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Once you generalize Ideal.comap_isMaximal_of_surjective
you can probably generalize all results in this section that assumes surjectivity (not sure about IsIntegral). For surjectivity it should still be true for Semirings that there is an OrderIso between ideals in R containing the kernel and all ideals in S.
Co-authored-by: Junyan Xu <junyanxu.math@gmail.com>
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Thanks 🎉
bors merge
Some results of PrimeSpectrum generalized from CommRing to CommSemiring. Co-authored-by: Xavier Xarles <56635243+XavierXarles@users.noreply.github.com>
Pull request successfully merged into master. Build succeeded: |
Some results of PrimeSpectrum generalized from CommRing to CommSemiring.