[Merged by Bors] - feat(RingTheory/WittVector): ring of Witt vectors is p-adically complete

[jjdishere]

In this PR, we show that if k is a perfect ring of char p, then the ring of Witt vectors is p-adically complete and p-torsion free.

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[github-actions]

PR summary baa25ed6dd

Import changes for modified files

No significant changes to the import graph

Import changes for all files

Files	Import difference
Mathlib.RingTheory.WittVector.Complete (new file)	1511

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Declarations diff

+ coe_refl_id
+ eq_zero_of_p_mul_eq_zero
+ isAdicCompleteIdealSpanP
+ iterate_verschiebung_coeff_eq_zero
+ iterate_verschiebung_iterate_frobenius
+ le_coeff_eq_iff_le_sub_coeff_eq_zero
+ mem_span_p_iff_coeff_zero_eq_zero
+ mem_span_p_pow_iff_le_coeff_eq_zero
+ mul_pow_charP_coeff_succ
+ mul_pow_charP_coeff_zero
+ verschiebung_injective

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 merge

[mathlib-bors]

Pull request successfully merged into master.

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