OAI.FiniteFactor.sourceSampling_mass_limit_event: intermediate lemma from OpenAI, Invariant-projection counterexamples for every irrational rotation

Proved

OAI.FiniteFactor.sourceSampling_mass_limit_event

by dbenbenn · Oct 25, 2026 · Mathlib 0df444a (Lean v4.33.1)

openai-math

An intermediate lemma of the split of OpenAI's proof of OAI.FiniteFactor.main_theorem, carved from OpenAI's openai/math development for this platform. The statement and its proof are OpenAI's (OpenAI, Invariant-projection counterexamples for every irrational rotation, OpenAI Math Release, September 27, 2026, result family 293, github.com/openai/math, Apache License 2.0); in Lean it is the declaration OAI.FiniteFactor.sourceSampling_mass_limit_event of lean/OAI/Analysis/FiniteFactor/OrbitSampling/Cube.lean at commit adc7f12, ported to Lean 4.33.1 and Mathlib 0df444a.

The statement, as published (namespace OAI.FiniteFactor, with open MeasureTheory Filter Finset, open scoped Classical ENNReal Topology):

theorem sourceSampling_mass_limit_event : ∀ᵐ θ ∂sourceAngleLaw,
    ∀ I : Finset SourceCoordinate,
      Tendsto (fun s => ((sourceSamplingUntrimmed I s θ) Set.univ).toReal)
        atTop (𝓝 (((sourceSamplingLambda I) Set.univ).toReal))

Definitions. The statement is written with OAI.FiniteFactor.SourceCoordinate, OAI.FiniteFactor.sourceAngleLaw, OAI.FiniteFactor.sourceSamplingLambda and OAI.FiniteFactor.sourceSamplingUntrimmed (definitions bundle OAIQ3Ff000 of this split).

Used by. The proof of OAI.FiniteFactor.exists_source_prepared_finite of this split imports it.

Preamble

import Mathlib
import Definitions.Def_OAIQ3Ff000

Formal statement

section

attribute [-instance] _root_.OAI.FiniteFactor.sourceBiasedRealMeasure_probability _root_.OAI.FiniteFactor.sourceSamplingTrimmed_finite _root_.OAI.FiniteFactor.sourceUnitCircle_probability
set_option linter.all false
set_option linter.unusedVariables false
set_option linter.unusedTactic false
set_option linter.unreachableTactic false

namespace OAI

namespace FiniteFactor
open MeasureTheory Filter Finset
open scoped Classical ENNReal Topology
noncomputable section

theorem sourceSampling_mass_limit_event : ∀ᵐ θ ∂sourceAngleLaw,
    ∀ I : Finset SourceCoordinate,
      Tendsto (fun s => ((sourceSamplingUntrimmed I s θ) Set.univ).toReal)
        atTop (𝓝 (((sourceSamplingLambda I) Set.univ).toReal)) := by
  sorry

end
end FiniteFactor

end OAI
end

Source

OpenAI, Invariant-projection counterexamples for every irrational rotation, OpenAI Math Release, September 27, 2026, https://github.com/openai/math (result family 293; paper: https://github.com/openai/math/blob/adc7f1241b42e322a6451854ab7e4b4c146bf78a/preprints/Invariant-projection-counterexamples-for-every-irrational-rotation-September-27-2026/paper.pdf; Apache License 2.0); Lean: https://github.com/openai/math/blob/adc7f1241b42e322a6451854ab7e4b4c146bf78a/lean/OAI/Analysis/FiniteFactor/OrbitSampling/Cube.lean (declaration OAI.FiniteFactor.sourceSampling_mass_limit_event)

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