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Geometric conditions for bounded point evaluations in several complex variables

Stephen Deterding

TL;DR

The paper addresses geometric conditions for the existence of bounded point evaluations on $L^p_a(U)$, the $L^p$-closure of analytic functions on a bounded domain $U\subset\mathbb{C}^d$, extending the one-variable Sobolev-capacity criterion to higher dimensions. It builds on the Bochner–Martinelli integral formula to represent evaluations as integrals and derives capacity-based bounds using annuli $A_n(x)$ and the Sobolev capacity $\Gamma_q$, with $q=p/(p-1)$ and $p>\frac{2d}{2d-1}$. The main result is a sufficient condition: if $\sum_{n=1}^\infty 2^{n(2d-1)q} \Gamma_q(A_n(x)\setminus U) < \infty$, then $x$ is a bounded point evaluation for $L^p_a(U)$; the bound is explicit in terms of this capacity sum. This work generalizes classical geometric criteria to several complex variables and ties bounded evaluation functionals to Sobolev capacity geometry, informing $L^p$-approximation and related analytic structures in higher dimensions.

Abstract

Let $U$ be a bounded domain in $\mathbb C^d$ and let $L^p_a(U)$, $1 \leq p < \infty$, denote the space of functions that are analytic on $\overline{U}$ and bounded in the $L^p$ norm on $U$. A point $x \in \overline{U}$ is said to be a bounded point evaluation for $L^p_a(U)$ if the linear functional $f \to f(x)$ is bounded in $L^p_a(U)$. In this paper, we provide a purely geometric condition given in terms of the Sobolev $q$-capacity for a point to be a bounded point evaluation for $L^p_a(U)$. This extends results known only for the single variable case to several complex variables.

Geometric conditions for bounded point evaluations in several complex variables

TL;DR

The paper addresses geometric conditions for the existence of bounded point evaluations on , the -closure of analytic functions on a bounded domain , extending the one-variable Sobolev-capacity criterion to higher dimensions. It builds on the Bochner–Martinelli integral formula to represent evaluations as integrals and derives capacity-based bounds using annuli and the Sobolev capacity , with and . The main result is a sufficient condition: if , then is a bounded point evaluation for ; the bound is explicit in terms of this capacity sum. This work generalizes classical geometric criteria to several complex variables and ties bounded evaluation functionals to Sobolev capacity geometry, informing -approximation and related analytic structures in higher dimensions.

Abstract

Let be a bounded domain in and let , , denote the space of functions that are analytic on and bounded in the norm on . A point is said to be a bounded point evaluation for if the linear functional is bounded in . In this paper, we provide a purely geometric condition given in terms of the Sobolev -capacity for a point to be a bounded point evaluation for . This extends results known only for the single variable case to several complex variables.

Paper Structure

This paper contains 3 sections, 4 theorems, 27 equations.

Key Result

Theorem 1

Let $X \subseteq \mathbb C$ be a compact set. Then for $p \geq 2$, $x$ is a bounded point evaluation on $R^p(X)$ if and only if where $q = \frac{p}{p-1}$ and $\Gamma_q(E)$ denotes the Sobolev $q$-capacity of $E$.

Theorems & Definitions (10)

  • Definition 1
  • Definition 2
  • Theorem 1
  • Definition 3
  • Theorem 2
  • Definition 4
  • Theorem 3: Bochner-Martinelli Integral Formula
  • Lemma 4
  • proof
  • proof