[Merged by Bors] - feat(RingTheory):Add lemma about factorPow

[Thmoas-Guan]

Add two lemma about factorPow.

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[github-actions]

PR summary 1ec6dfbfd3

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

+ Ideal.map_mk_comap_factor
+ Ideal.map_mk_comap_factorPow
+ factorPowSucc.isUnit_of_isUnit_image

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).

[Ruben-VandeVelde]

Thanks; some superficial comments below

[riccardobrasca]

Taking into account the above comments LGTM, thanks!

bors d+

[mathlib-bors]

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

[Thmoas-Guan]

@riccardobrasca There are some bit more changes, can you have a look? Thanks
Also, do we need the version for factorPow instead of factorPowSucc for isUnit_of_IsUnit_image? I remember @jjdishere once mentioned a method to deal with it?

[riccardobrasca]

LGTM. We can always add another lemma later.

bors d+

[mathlib-bors]

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

[Thmoas-Guan]

bors r+

[mathlib-bors]

Pull request successfully merged into master.

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