feat(RingTheory/Valuation/ValuationSubring): algebraic instances

[mariainesdff]

Given a valuation subring A, if A.valuation is trivial on k, A is a k-algebra.

Co-authored-by: @xgenereux

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[github-actions]

PR summary 227303e4cc

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 (regex)

+ algebraMap_mem_of_isTrivialOn
+ algebraOfIsTrivialOn
+ isScalarTowerOfIsTrivialOn
+ isTrivialOn_valuationSubring_valuation

You can run this locally as follows

## from your `mathlib4` directory:
git clone https://github.com/leanprover-community/mathlib-ci.git ../mathlib-ci

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

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

The doc-module for scripts/pr_summary/declarations_diff.sh in the mathlib-ci repository contains some details about this script.

Declarations diff (Lean)

✅ Lean-aware diff — post-build, computed from the Lean environment (commit 227303e).

• +4 new declarations
• −0 removed declarations

+Valuation.isTrivialOn_valuationSubring_valuation
+ValuationSubring.algebraMap_mem_of_isTrivialOn
+ValuationSubring.algebraOfIsTrivialOn
+ValuationSubring.isScalarTowerOfIsTrivialOn

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No changes to strong technical debt.
No changes to weak technical debt.

Current commit 227303e4cc
Reference commit 9a1338a6a1

This script lives in the mathlib-ci repository. To run it locally, from your mathlib4 directory:

git clone https://github.com/leanprover-community/mathlib-ci.git ../mathlib-ci
../mathlib-ci/scripts/reporting/technical-debt-metrics.py 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).