feat(Algebra/Polynomial): lemmas about polynomial degree

[artie2000]

• Add various small lemmas about polynomial degree

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[github-actions]

PR summary 6b3e5a3312

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

+ degree_eq_iff_natDegree_eq_of_atLeastTwo
+ degree_eq_one_iff_natDegree_eq_one
+ degree_sub_lt_right
+ natDegree_add_one
+ natDegree_le_of_dvd
+ natDegree_normalize
+ natDegree_one_add

You can run this locally as follows

## summary with just the declaration names:
./scripts/pr_summary/declarations_diff.sh <optional_commit>

## more verbose report:
./scripts/pr_summary/declarations_diff.sh long <optional_commit>

The doc-module for scripts/pr_summary/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/reporting/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]

I think this should be the other way around? I find degree to be better behaved than natDegree. Maybe worth getting a second opinion.

[vihdzp]

This should either take an n ≠ 0 argument, or if you really want to use typeclasses for whatever reason, this should take NeZero n.

[vihdzp]

Perhaps the other theorem should be renamed degree_sub_lt_left.