feat(RingTheory/Flat): finite flat algebra is trivial if rank is equal to 1

[chrisflav]

From Pi1.

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[github-actions]

PR summary 3bd2603b81

Import changes for modified files

No significant changes to the import graph

Import changes for all files

Files	Import difference
Mathlib.RingTheory.Flat.Rank (new file)	2130

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Declarations diff

+ Module.Flat.tfae_algebraMap_surjective
+ Module.Free.bijective_algebraMap_of_finrank_eq_one
+ Module.algebraMap_bijective_iff_rankAtStalk
+ Module.algebraMap_bijective_of_rankAtStalk
+ Module.algebraMap_surjective_of_rankAtStalk_le_one
+ Module.rankAtStalk_le_one_iff_surjective
+ Module.rankAtStalk_pos_iff_algebraMap_injective
+ PrimeSpectrum.comap_surjective_iff_injective_of_finite
+ PrimeSpectrum.rankAtStalk_pos_iff_comap_surjective
+ PrimeSpectrum.rankAtStalk_pos_iff_mem_range_comap
+ _root_.Algebra.IsIntegral.comap_surjective
+ instance {T : Type*} [CommSemiring T] [Algebra R T] :
+ mul'_bijective_of_surjective

You can run this locally as follows

## summary with just the declaration names:
./scripts/pr_summary/declarations_diff.sh <optional_commit>

## more verbose report:
./scripts/pr_summary/declarations_diff.sh long <optional_commit>

The doc-module for scripts/pr_summary/declarations_diff.sh contains some details about this script.

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Increase in tech debt: (relative, absolute) = (1.00, 0.00)

Current number	Change	Type
6900	1	backward.isDefEq.respectTransparency

Current commit 6a03db0720
Reference commit 3bd2603b81

You can run this locally as

./scripts/reporting/technical-debt-metrics.sh pr_summary

• The relative value is the weighted sum of the differences with weight given by the inverse of the current value of the statistic.
• The absolute value is the relative value divided by the total sum of the inverses of the current values (i.e. the weighted average of the differences).

[chrisflav]

Thanks for the review @robin-carlier!

[robin-carlier]

Thanks!

maintainer merge

[github-actions]

🚀 Pull request has been placed on the maintainer queue by robin-carlier.