A uniform bound for the Cauchy transform of compactly supported data,
ProvedJHolomorphic.norm_integral_inv_sub_smul_leelliptic-regularitypseudoholomorphic-curvessobolev-spaces
Let , and let be a complex normed space. There is a constant such that for every vanishing outside the open disc and every , the map is Lebesgue integrable on and
This is the uniform bound for the Cauchy transform of compactly supported data, , used to build local solutions of Cauchy–Riemann type equations.
Formalization Note with MemLp g (ENNReal.ofReal p) volume and Function.support g ⊆ ball 0 R; the integrand is (z - ζ)⁻¹ • g ζ (complex scalar multiplication), and the bound is ‖∫ ζ, (z - ζ)⁻¹ • g ζ‖ ≤ C * (eLpNorm g (ENNReal.ofReal p) volume).toReal.
Preamble
import Definitions.Def_JHolomorphic_Setting import Mathlib.MeasureTheory.Function.LpSeminorm.CompareExp import Mathlib.MeasureTheory.Constructions.HaarToSphere import Mathlib.MeasureTheory.Measure.Lebesgue.Complex import Mathlib.MeasureTheory.Measure.Lebesgue.EqHaar import Mathlib.MeasureTheory.Measure.Haar.Unique import Mathlib.MeasureTheory.Group.Measure import Mathlib.Analysis.SpecialFunctions.Integrability.Basic import Mathlib.LinearAlgebra.Complex.FiniteDimensional
Formal statement
namespace JHolomorphic
open MeasureTheory Metric Filter Topology Set
open scoped ContDiff ENNReal NNReal
/-- Let `2 < p < ∞` and `R > 0`. There is `C ≥ 0` such that for every `g ∈ L^p(ℂ; E)` vanishing
outside the disc `B_R(0)` and every `z ∈ B_R(0)`, the map `ζ ↦ (z - ζ)⁻¹ g(ζ)` is integrable and
`‖∫ (z - ζ)⁻¹ g(ζ) dζ‖ ≤ C ‖g‖_{L^p}`. -/
theorem norm_integral_inv_sub_smul_le {E : Type*} [NormedAddCommGroup E] [NormedSpace ℂ E]
(p R : ℝ) (hp : 2 < p) (hR : 0 < R) :
∃ C : ℝ, 0 ≤ C ∧ ∀ g : ℂ → E, MemLp g (ENNReal.ofReal p) volume →
Function.support g ⊆ ball 0 R → ∀ z ∈ ball (0 : ℂ) R,
Integrable (fun ζ => (z - ζ)⁻¹ • g ζ) ∧
‖∫ ζ, (z - ζ)⁻¹ • g ζ‖ ≤ C * (eLpNorm g (ENNReal.ofReal p) volume).toReal := by
sorry
end JHolomorphic
Source
Standard estimate for the Cauchy transform; used for C. Wendl, Lectures on Symplectic Field Theory, arXiv:1612.01009, Lecture 2, Lemma 2.24