OAI/Geometry/RCD/Metric/VolumeBudget.lean

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The dyadic volume-defect budget

Successive volume increments telescope, while the rescaled curvature contribution is a geometric series. Both monotone bounded profiles and raw profiles converging to a bounded density are treated. This is the scalar summation argument in the proof of the manuscript's Poisson pinching lemma.

  1. theorem OAI.RegularPointCoordinates.volume_profile_increment_sum line 23

    Source documentation

    The finite sum of consecutive normalized-volume increments telescopes.

    theorem volume_profile_increment_sum (A : ℕ → ℝ) (k : ℕ) :
        (∑ i ∈ Finset.range k, (A (i + 1) - A i)) = A k - A 0 := by
    …
  2. theorem OAI.RegularPointCoordinates.sum_range_quarter_pow_le line 32

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    The curvature correction at dyadic radii has total mass at most 4 / 3.

    theorem sum_range_quarter_pow_le (k : ℕ) :
        (∑ i ∈ Finset.range k, (1 / 4 : ℝ) ^ i) ≤ 4 / 3 := by
    …
  3. theorem OAI.RegularPointCoordinates.volume_profile_increments_summable line 48

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    A monotone volume profile bounded by Euclidean volume has summable successive increments.

    theorem volume_profile_increments_summable {A : ℕ → ℝ} {omega : ℝ}
        (hmono : Monotone A) (hupper : ∀ i, A i ≤ omega) :
        Summable (fun i => A (i + 1) - A i) := by
    …
  4. theorem OAI.RegularPointCoordinates.volume_defect_partial_sum_telescope line 59

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    Finite Poisson-defect sums are controlled by the corresponding volume drop and the partial curvature series.

    theorem volume_defect_partial_sum_telescope {A P : ℕ → ℝ} {C kappa : ℝ}
        (hbound : ∀ i, P i ≤ C * (A (i + 1) - A i + kappa * (1 / 4 : ℝ) ^ i))
        (k : ℕ) :
        (∑ i ∈ Finset.range k, P i) ≤
          C * (A k - A 0 + kappa * ∑ i ∈ Finset.range k, (1 / 4 : ℝ) ^ i) := by
    …
  5. theorem OAI.RegularPointCoordinates.volume_defect_partial_sum_le line 71

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    Uniform finite-scale bound by the initial volume deficit and curvature.

    theorem volume_defect_partial_sum_le {A P : ℕ → ℝ} {C kappa omega : ℝ}
        (hC : 0 ≤ C) (hkappa : 0 ≤ kappa) (hupper : ∀ i, A i ≤ omega)
        (hbound : ∀ i, P i ≤ C * (A (i + 1) - A i + kappa * (1 / 4 : ℝ) ^ i))
        (k : ℕ) :
        (∑ i ∈ Finset.range k, P i) ≤ C * (omega - A 0 + kappa * (4 / 3)) := by
    …
  6. theorem OAI.RegularPointCoordinates.volume_defect_summable line 83

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    Comparison with the summable volume increments and curvature series proves summability of the nonnegative defects.

    theorem volume_defect_summable {A P : ℕ → ℝ} {C kappa omega : ℝ}
        (hmono : Monotone A) (hupper : ∀ i, A i ≤ omega) (hP : ∀ i, 0 ≤ P i)
        (hbound : ∀ i, P i ≤ C * (A (i + 1) - A i + kappa * (1 / 4 : ℝ) ^ i)) :
        Summable P := by
    …
  7. theorem OAI.RegularPointCoordinates.volume_defect_tsum_le line 97

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    The complete defect budget depends only on the initial volume deficit and the curvature parameter.

    theorem volume_defect_tsum_le {A P : ℕ → ℝ} {C kappa omega : ℝ}
        (hC : 0 ≤ C) (hkappa : 0 ≤ kappa) (hupper : ∀ i, A i ≤ omega)
        (hP : ∀ i, 0 ≤ P i)
        (hbound : ∀ i, P i ≤ C * (A (i + 1) - A i + kappa * (1 / 4 : ℝ) ^ i)) :
        (∑' i, P i) ≤ C * (omega - A 0 + kappa * (4 / 3)) := by
    …
  8. theorem OAI.RegularPointCoordinates.volume_defect_budget line 106

    Source documentation

    Summability and the quantitative total bound in one application.

    theorem volume_defect_budget {A P : ℕ → ℝ} {C kappa omega : ℝ}
        (hC : 0 ≤ C) (hkappa : 0 ≤ kappa)
        (hmono : Monotone A) (hupper : ∀ i, A i ≤ omega) (hP : ∀ i, 0 ≤ P i)
        (hbound : ∀ i, P i ≤ C * (A (i + 1) - A i + kappa * (1 / 4 : ℝ) ^ i)) :
        Summable P ∧ (∑' i, P i) ≤ C * (omega - A 0 + kappa * (4 / 3)) :=
    …
  9. theorem OAI.RegularPointCoordinates.volume_defect_budget_of_profile_limit line 117

    Source documentation

    The raw Euclidean-normalized volume profile can approach its density from either side. Its convergence is enough for the same defect budget; monotonicity of that raw profile is not needed.

    theorem volume_defect_budget_of_profile_limit {A P : ℕ → ℝ}
        {C kappa omega density : ℝ} (hC : 0 ≤ C)
        (hA : Tendsto A atTop (𝓝 density)) (hdensity : density ≤ omega)
        (hP : ∀ i, 0 ≤ P i)
        (hbound : ∀ i, P i ≤ C * (A (i + 1) - A i + kappa * (1 / 4 : ℝ) ^ i)) :
        Summable P ∧ (∑' i, P i) ≤ C * (omega - A 0 + kappa * (4 / 3)) := by
    …
  10. theorem OAI.RegularPointCoordinates.volume_defect_totals_tendsto_zero line 150

    Source documentation

    Vanishing initial volume deficit and rescaled curvature force the total nonnegative defect to vanish along a sequence of rescalings.

    theorem volume_defect_totals_tendsto_zero {P : ℕ → ℕ → ℝ}
        {initialVolume kappa : ℕ → ℝ} {C omega : ℝ}
        (hvolume : Tendsto initialVolume atTop (𝓝 omega))
        (hkappa : Tendsto kappa atTop (𝓝 0)) (hP : ∀ nu i, 0 ≤ P nu i)
        (hbudget : ∀ nu, (∑' i, P nu i) ≤
          C * (omega - initialVolume nu + kappa nu * (4 / 3))) :
        Tendsto (fun nu => ∑' i, P nu i) atTop (𝓝 0) := by
    …