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[Merged by Bors] - feat(CategoryTheory): the equivalence of categories induced by a bijection#20881

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induced-category-equivalence-of-equiv
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[Merged by Bors] - feat(CategoryTheory): the equivalence of categories induced by a bijection#20881
joelriou wants to merge 1 commit intomasterfrom
induced-category-equivalence-of-equiv

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@joelriou joelriou commented Jan 20, 2025

When f : T → D is a map and D is a category, then InducedCategory D f is a category with objects T with a fully faithful functor to D. In this PR, we show that in the case of a bijection T ≃ D, the induced category is equivalent to D.

The code would be nicer (see #19945) if the type of morphisms in the induced category was defined as a 1-field structure. This would be a very welcomed refactor.


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PR summary 1c8cca8aa6

Import changes for modified files

No significant changes to the import graph

Import changes for all files
Files Import difference

Declarations diff

+ Equivalence.induced

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.


Increase in tech debt: (relative, absolute) = (2.00, 0.00)
Current number Change Type
1415 2 erw

Current commit 1c8cca8aa6
Reference commit f033341c29

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).

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Thanks!
bors r+

@ghost ghost added the ready-to-merge This PR has been sent to bors. label Jan 21, 2025
mathlib-bors bot pushed a commit that referenced this pull request Jan 21, 2025
…ction (#20881)

When `f : T → D` is a map and `D` is a category, then `InducedCategory D f` is a category with objects `T` with a fully faithful functor to `D`. In this PR, we show that in the case of a bijection `T ≃ D`, the induced category is equivalent to `D`.

The code would be nicer (see #19945) if the type of morphisms in the induced category was defined as a 1-field structure. This would be a very welcomed refactor.
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mathlib-bors bot commented Jan 21, 2025

Pull request successfully merged into master.

Build succeeded:

@mathlib-bors mathlib-bors bot changed the title feat(CategoryTheory): the equivalence of categories induced by a bijection [Merged by Bors] - feat(CategoryTheory): the equivalence of categories induced by a bijection Jan 21, 2025
@mathlib-bors mathlib-bors bot closed this Jan 21, 2025
@mathlib-bors mathlib-bors bot deleted the induced-category-equivalence-of-equiv branch January 21, 2025 07:39
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