[Merged by Bors] - feat(CategoryTheory/Category/Preorder): isIso_homOfLE

[joelriou]

We add the lemma isIso_homOfLE which shows that homOfLE is an isomorphism when x = y.

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[github-actions]

PR summary 2b4c6152f1

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

+ isIso_homOfLE

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).

[vihdzp]

This can be weakened to AntisymmRel (· ≤ ·) x y, right?

[joelriou]

This would require an extra import. Anyway, the more useful basic lemma would still be the one using an equality as an assumption.

[vihdzp]

If AntisymmRel is a heavy import by any measure, then we should refactor the file!

[robin-carlier]

I also think not much is gained by generalizing to AntisymmRel, and that the most important case that will show up in practice in almost all cases is the one with equality,
so

Thanks!

maintainer merge

[github-actions]

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

[jcommelin]

Thanks 🎉

bors merge

[mathlib-bors]

Build failed (retrying...):

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[mathlib-bors]

Canceled.

[joelriou]

Retrying....

bors merge

[mathlib-bors]

Pull request successfully merged into master.

Build succeeded:

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