[Merged by Bors] - feat(Algebra/AlgHom): Unique if target is Subsingleton

[chrisflav]

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[github-actions]

PR summary e6edd78610

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

+ AlgEquiv.default_apply
+ AlgHom.default_apply
+ instance [Subsingleton S] [Subsingleton T] : Unique (S ≃ₐ[R] T)
+ uniqueOfRight

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).

[chrisflav]

Any further comments @eric-wieser?

[erdOne]

This PR has been stale for months now. The comment was not resolved but I think Christian's reply is reasonable, and I don't think this should go in Subalgebra.Lattice.

maintainer merge

[leanprover-community-bot-assistant]

This pull request has conflicts, please merge master and resolve them.

[erdOne]

maintainer delegate

[github-actions]

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

[erdOne]

(why did my previous invocation not work?)

[riccardobrasca]

Thanks!

bors d+

[mathlib-bors]

✌️ chrisflav can now approve this pull request. To approve and merge a pull request, simply reply with bors r+. More detailed instructions are available here.

[chrisflav]

bors r+

[mathlib-bors]

Pull request successfully merged into master.

Build succeeded:

• CI Success