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Measure theory 1.3.5: complete Lebesgue measurability fixes#549

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Chessing234:fix/measure-1-3-5-egorov-lusin-complete
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Measure theory 1.3.5: complete Lebesgue measurability fixes#549
Chessing234 wants to merge 1 commit into
teorth:mainfrom
Chessing234:fix/measure-1-3-5-egorov-lusin-complete

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Summary

  • Replace MeasurableSet with LebesgueMeasurable for exceptional sets in Egorov's theorem, Lusin's theorem, and the Littlewood principle (Section 1.3.5)
  • Add LebesgueMeasurable S to uniformlyConverges_outside_small so the finite-measure set hypothesis is well-typed
  • Fix LocallyComplexAbsolutelyIntegrable to quantify over Lebesgue measurable bounded sets

Combines the fixes from #547 and #548 into one PR for easier review.

Test plan

  • lake build succeeds
  • Section 1.3.5 statements typecheck with the updated hypotheses

Made with Cursor

Egorov/Lusin exceptional sets should be Lebesgue measurable, not merely
Borel. Also require S measurable for uniform convergence on S^c union E,
and fix LocallyComplexAbsolutelyIntegrable to quantify over Lebesgue sets.

Co-authored-by: Cursor <cursoragent@cursor.com>
@Chessing234

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Egorov/Lusin talk about Lebesgue-null exceptional sets, so the hypotheses should be Lebesgue measurable, not Borel. Also need S measurable before taking Lebesgue_measure S < ⊤ in the uniform-convergence remark.

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