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feat(MeasureTheory.VectorMeasure): add several lemmas which characterize variation#26160

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oliver-butterley:variation-lemmas-1
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feat(MeasureTheory.VectorMeasure): add several lemmas which characterize variation#26160
oliver-butterley wants to merge 143 commits intoleanprover-community:masterfrom
oliver-butterley:variation-lemmas-1

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@oliver-butterley oliver-butterley commented Jun 19, 2025

Add the following lemmas concerning variation of a VectorMeasure:

  • norm_measure_le_variation: ‖μ E‖ₑ ≤ variation μ E.
  • variation_neg: (-μ).variation = μ.variation.
  • variation_zero: (0 : VectorMeasure X V).variation = 0.
  • absolutelyContinuous

Co-authored-by: @yoh-tanimoto


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@yoh-tanimoto yoh-tanimoto removed the awaiting-author A reviewer has asked the author a question or requested changes. label Mar 31, 2026
@EtienneC30 EtienneC30 self-assigned this Mar 31, 2026
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Here is a new round of comments:

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Here is a new round of comments: Sorry, github bug.

@EtienneC30 EtienneC30 added the awaiting-author A reviewer has asked the author a question or requested changes. label Mar 31, 2026
@yoh-tanimoto yoh-tanimoto removed the awaiting-author A reviewer has asked the author a question or requested changes. label Apr 2, 2026
@EtienneC30 EtienneC30 added the awaiting-author A reviewer has asked the author a question or requested changes. label Apr 2, 2026
ne_eq, and_imp]
grind
calc
∑ p ∈ P, ‖μ p‖ₑ = ∑ p ∈ Q.parts, ‖μ p‖ₑ := by
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As there are already several lemmas about sums in the Finpartition file, maybe this should go there as well after the definition of ofPairwiseDisjoint.

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defined sum_ofPairwiseDisjoint_eq_sum and sum_ofSubset_eq_sum.

@yoh-tanimoto yoh-tanimoto removed the awaiting-author A reviewer has asked the author a question or requested changes. label Apr 3, 2026
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Nearly there!

@EtienneC30 EtienneC30 added the awaiting-author A reviewer has asked the author a question or requested changes. label Apr 3, 2026
@yoh-tanimoto yoh-tanimoto removed the awaiting-author A reviewer has asked the author a question or requested changes. label Apr 3, 2026
Comment on lines +18 to +19
When `μ` is a signed measure, it will be shown that `μ.variation E = μ.totalVariation E`. When `μ`
is `ℝ≥0∞`-valued measure, `μ.variation` coincides with `μ` on measurable sets.
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This is not in the PR, correct? If so, please either add this as a TODO, or remove it if you are already working on it.

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correct, they are signedMeasure_totalVariation_eq in #26168 and variation_of_ENNReal in #26125, respectively. I removed it.

@EtienneC30 EtienneC30 added the awaiting-author A reviewer has asked the author a question or requested changes. label Apr 4, 2026
@yoh-tanimoto yoh-tanimoto removed the awaiting-author A reviewer has asked the author a question or requested changes. label Apr 4, 2026
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