OAI/Geometry/RCD/Sobolev/PositiveSourceMoment.lean

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The moment estimate used for positive Poisson sources

A weak power-tail bound of exponent d gives every smaller positive moment. In the Poisson argument the tail follows by testing with a truncation and applying the Dirichlet Sobolev inequality. The constants below do not depend on an upper bound for the solution.

  1. theorem OAI.RegularPointCoordinates.lintegral_small_rpow line 22
  2. theorem OAI.RegularPointCoordinates.lintegral_large_rpow line 36
  3. theorem OAI.RegularPointCoordinates.moment_lintegral_le_of_power_tail line 53

    Source documentation

    A tail bound at levels at least one gives an explicit smaller-moment bound; low levels cost only the total measure.

    theorem moment_lintegral_le_of_power_tail {X : Type*} [MeasurableSpace X]
        (μ : Measure X) [IsFiniteMeasure μ] {H : X → ℝ}
        (hH : AEMeasurable H μ) (hH0 : 0 ≤ᵐ[μ] H)
        {q d C : ℝ} (hq : 0 < q) (hqd : q < d) (hC : 0 ≤ C)
        (htail : ∀ t : ℝ, 1 ≤ t → μ {x | t ≤ H x} ≤ ENNReal.ofReal (C * t ^ (-d))) :
        (∫⁻ x, ENNReal.ofReal (H x ^ q) ∂μ) ≤
          ENNReal.ofReal q *
            (μ univ * ENNReal.ofReal q⁻¹ + ENNReal.ofReal C * ENNReal.ofReal (d - q)⁻¹) := by
    …
  4. theorem OAI.RegularPointCoordinates.integrable_rpow_of_power_tail line 93

    Source documentation

    The tail estimate also supplies genuine integrability of the moment.

    theorem integrable_rpow_of_power_tail {X : Type*} [MeasurableSpace X]
        (μ : Measure X) [IsFiniteMeasure μ] {H : X → ℝ}
        (hH : AEMeasurable H μ) (hH0 : 0 ≤ᵐ[μ] H)
        {q d C : ℝ} (hq : 0 < q) (hqd : q < d) (hC : 0 ≤ C)
        (htail : ∀ t : ℝ, 1 ≤ t → μ {x | t ≤ H x} ≤ ENNReal.ofReal (C * t ^ (-d))) :
        Integrable (fun x => H x ^ q) μ := by
    …
  5. theorem OAI.RegularPointCoordinates.integral_rpow_le_of_power_tail line 110

    Source documentation

    A real-valued form of the moment bound for subsequent energy estimates.

    theorem integral_rpow_le_of_power_tail {X : Type*} [MeasurableSpace X]
        (μ : Measure X) [IsFiniteMeasure μ] {H : X → ℝ}
        (hH : AEMeasurable H μ) (hH0 : 0 ≤ᵐ[μ] H)
        {q d C : ℝ} (hq : 0 < q) (hqd : q < d) (hC : 0 ≤ C)
        (htail : ∀ t : ℝ, 1 ≤ t → μ {x | t ≤ H x} ≤ ENNReal.ofReal (C * t ^ (-d))) :
        (∫ x, H x ^ q ∂μ) ≤ q * (μ.real univ * q⁻¹ + C * (d - q)⁻¹) := by
    …