[Merged by Bors] - feat(Algebra/Module/CharacterModule): a morphism of abelian groups is bijective if and only if its dual is bijective

[smorel394]

Prove that a morphism of abelian groups f is surjective if and only if its dual is injective, deduce that f is bijective if and only if its dual is bijective.

Note: here we use duality with coefficients in ℚ ⧸ ℤ.

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[github-actions]

PR summary c717a8a41f

Import changes for modified files

No significant changes to the import graph

Import changes for all files

Files	Import difference

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Declarations diff

+ dual_bijective_iff_bijective
+ dual_comp
+ dual_injective_iff_surjective
+ dual_injective_of_surjective
+ dual_zero
+ surjective_of_dual_injective

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.

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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).

[alreadydone]

Thanks!
maintainer delegate

[github-actions]

🚀 Pull request has been placed on the maintainer queue by alreadydone.

[riccardobrasca]

Thanks!

bors merge

[mathlib-bors]

Pull request successfully merged into master.

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