OAI/MeasureTheory/Falconer/Fourier/PhaseIntegration.lean

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Coordinate integration by parts for the angular localization

For an arbitrary smooth real phase in a sphere chart, coordinate integration by parts gives a scale bound through the reciprocal phase derivative. The transport derivative identities concern functions on the real line and are independent of the ambient sphere dimension.

  1. def OAI.Falconer.phaseOscillator line 19
  2. theorem OAI.Falconer.phaseOscillator_norm line 22
  3. theorem OAI.Falconer.phaseOscillator_hasDerivAt line 26
  4. theorem OAI.Falconer.phase_integration_by_parts line 35
  5. theorem OAI.Falconer.phase_transport_iterate_integral line 80
  6. theorem OAI.Falconer.phase_nonstationary_scale_bound line 102

    Source documentation

    Uniform coordinate IBP. The reciprocal derivative has size U and derivative scale D; the gain per integration is U*D/Λ.

    theorem phase_nonstationary_scale_bound {φ : ℝ → ℝ} {q f : ℝ → ℂ}
        (hφ : ContDiff ℝ ∞ φ) (hq : ContDiff ℝ ∞ q) (hf : ContDiff ℝ ∞ f)
        {a b : ℝ} (hab : a ≤ b) (hs : tsupport f ⊆ Icc a b)
        (hrecip : ∀ x ∈ tsupport f, ((deriv φ x : ℝ) : ℂ) * q x = 1)
        (Q : ℕ → ℝ) (hQ : ∀ k, 0 ≤ Q k)
        {C U D Λ : ℝ} (hC : 0 ≤ C) (hU : 0 ≤ U) (hD : 0 ≤ D) (hΛ : 0 < Λ)
        (n : ℕ)
        (hbq : ∀ k ≤ n, ∀ x ∈ tsupport f, ‖iteratedDeriv k q x‖ ≤ Q k * U * D^k)
        (hbf : ∀ k ≤ n, ∀ x ∈ tsupport f, ‖iteratedDeriv k f x‖ ≤ C * D^k) :
        ‖∫ x, phaseOscillator φ Λ x * f x‖ ≤
          (PlanarFalconer.scaledAngularTransportCost Q n 0 * C * (b-a)) * (U*D/Λ)^n := by
    …

    Mentions: OAI.Falconer.phaseOscillator, OAI.PlanarFalconer.scaledAngularTransportCost