[Merged by Bors] - feat(RingTheory/UniqueFactorizationDomain/Basic): associated elements have the same number of factors

[tb65536]

This PR proves that associated elements have the same number of factors (this follows from the preceeding lemma factors_unique).

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[github-actions]

PR summary e56beffe25

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

+ _root_.Associated.card_factors_eq

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).

[jcommelin]

Thanks 🎉

bors d+

[mathlib-bors]

✌️ tb65536 can now approve this pull request. To approve and merge a pull request, simply reply with bors r+. More detailed instructions are available here.

[jcommelin]

Thanks 🎉

bors merge

[mathlib-bors]

Pull request successfully merged into master.

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