OAI/NumberTheory/TwoPoint/Halasz/HalaszWindowSampling.lean

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A finite sampling inequality from the compact coefficient-torus window. The right side counts actual nearby pairs of sampling centers.

  1. lemma OAI.TwoPointCorrelations.halasz_character_window_inner line 12
  2. theorem OAI.TwoPointCorrelations.halasz_window_sampling line 31

    Source documentation

    Finite Fourier sampling costs only the volume of the window times the number of pairs of centers whose translated windows can meet.

    theorem halasz_window_sampling {ι : Type*} {k : ℕ}
        (B : Finset ι) (S : Finset (Fin k → ℤ))
        (β : ι → Fin k → AddCircle (1:ℝ)) (a : ι → ℂ) (δ : Fin k → ℝ)
        (ha : ∀ b∈B,‖a b‖≤1) (hδ : ∀ j,0≤δ j) (hδhalf : ∀ j,δ j≤1/2)
        (hphase : ∀ m∈S,∀ j,2*Real.pi*|(m j:ℝ)| * δ j≤1) :
        (∏ j,δ j)^2*(∑ m∈S,‖∑ b∈B,a b*halaszVinogradovCharacter m (β b)‖^2)≤
          (∏ j,2*δ j)*
            (((B×ˢB).filter (fun p => HalaszWindowNear δ (β p.1) (β p.2))).card:ℝ) := by
    …

    Mentions: OAI.TwoPointCorrelations.halaszVinogradovCharacter, OAI.TwoPointCorrelations.HalaszWindowNear