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[Merged by Bors] - feat(Algebra/Colimit): the directed system of finitely generated submodules#20264

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[Merged by Bors] - feat(Algebra/Colimit): the directed system of finitely generated submodules#20264
alreadydone wants to merge 2 commits intomasterfrom
fgSystem

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We show that every module is the direct limit of its finitely generated submodules.

As a consequence of this and the fact that tensor products preserves colimits, we show that if M and P are arbitrary modules and N is a finitely generated submodule of a module P, then two elements of N ⊗ M have the same image in P ⊗ M if and only if they already have the same image in N' ⊗ M for some finitely generated submodule N' ≥ N. This is the theorem Submodule.FG.exists_rTensor_fg_inclusion_eq.


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@alreadydone alreadydone added the t-algebra Algebra (groups, rings, fields, etc) label Dec 27, 2024
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github-actions bot commented Dec 27, 2024

PR summary 4d36c01dcd

Import changes for modified files

No significant changes to the import graph

Import changes for all files
Files Import difference
Mathlib.Algebra.Colimit.Finiteness (new file) 974
Mathlib.Algebra.Colimit.TensorProduct (new file) 979

Declarations diff

+ Submodule.FG.exists_rTensor_fg_inclusion_eq
+ directLimitLeft_rTensor_of
+ equiv
+ equiv_comp_of
+ exists_eq_of_of_eq
+ fgSystem
+ instance : DirectedSystem (G · ⊗[R] M) (f ▷ M)
+ instance : DirectedSystem (M ⊗[R] G ·) (M ◁ f)
+ instance : DirectedSystem _ (fgSystem R M · · · ·)
+ instance : IsDirected {N : Submodule R M // N.FG} (· ≤ ·)

You can run this locally as follows
## summary with just the declaration names:
./scripts/declarations_diff.sh <optional_commit>

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

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


No changes to technical debt.

You can run this locally as

./scripts/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).

@jcommelin jcommelin added the awaiting-author A reviewer has asked the author a question or requested changes. label Jan 2, 2025
@alreadydone alreadydone removed the awaiting-author A reviewer has asked the author a question or requested changes. label Jan 2, 2025
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Thanks 🎉

bors merge

@ghost ghost added the ready-to-merge This PR has been sent to bors. label Jan 2, 2025
mathlib-bors bot pushed a commit that referenced this pull request Jan 2, 2025
…odules (#20264)

We show that every module is the direct limit of its finitely generated submodules.

As a consequence of this and the fact that tensor products preserves colimits, we show that if `M` and `P` are arbitrary modules and `N` is a finitely generated submodule of a module `P`, then two elements of `N ⊗ M` have the same image in `P ⊗ M` if and only if they already have the same image in `N' ⊗ M` for some finitely generated submodule `N' ≥ N`. This is the theorem `Submodule.FG.exists_rTensor_fg_inclusion_eq`.
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mathlib-bors bot commented Jan 2, 2025

Pull request successfully merged into master.

Build succeeded!

And happy new year! 🎉

@mathlib-bors mathlib-bors bot changed the title feat(Algebra/Colimit): the directed system of finitely generated submodules [Merged by Bors] - feat(Algebra/Colimit): the directed system of finitely generated submodules Jan 2, 2025
@mathlib-bors mathlib-bors bot closed this Jan 2, 2025
@mathlib-bors mathlib-bors bot deleted the fgSystem branch January 2, 2025 20:19
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2 participants