Quantitative boundary Hölder estimates for the inhomogeneous Poisson problem through a probabilistic approach

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Main Authors: Cîmpean, Iulian, Popescu, Ionel, Zarnescu, Arghir
Format: Preprint
Published: 2025
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author Cîmpean, Iulian
Popescu, Ionel
Zarnescu, Arghir
author_facet Cîmpean, Iulian
Popescu, Ionel
Zarnescu, Arghir
contents In this paper we derive quantitative boundary Hölder estimates, with explicit constants, for the inhomogeneous Poisson problem in a bounded open set $D\subset \mathbb{R}^d$. Our approach has two main steps: firstly, we consider an arbitrary $D$ as above and prove that the boundary $α$-Hölder regularity of the solution the Poisson equation is controlled, with explicit constants, by the Hölder seminorm of the boundary data, the $L^ γ$-norm of the forcing term with $γ>d/2$, and the $α/2$-moment of the exit time from $D$ of the Brownian motion. Secondly, we derive explicit estimates for the $α/2$-moment of the exit time in terms of the distance to the boundary, the regularity of the domain $D$, and $α$. Using this approach, we derive explicit estimates for the same problem in domains satisfying exterior ball conditions, respectively exterior cone/wedge conditions, in terms of simple geometric features. As a consequence we also obtain explicit constants for pointwise estimates for the Green function and for the gradient of the solution. The obtained estimates can be employed to bypass the curse of high dimensions when aiming to approximate the solution of the Poisson problem using neural networks, obtaining polynomial scaling with dimension, which in some cases can be shown to be optimal.
format Preprint
id arxiv_https___arxiv_org_abs_2510_06906
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Quantitative boundary Hölder estimates for the inhomogeneous Poisson problem through a probabilistic approach
Cîmpean, Iulian
Popescu, Ionel
Zarnescu, Arghir
Probability
Analysis of PDEs
In this paper we derive quantitative boundary Hölder estimates, with explicit constants, for the inhomogeneous Poisson problem in a bounded open set $D\subset \mathbb{R}^d$. Our approach has two main steps: firstly, we consider an arbitrary $D$ as above and prove that the boundary $α$-Hölder regularity of the solution the Poisson equation is controlled, with explicit constants, by the Hölder seminorm of the boundary data, the $L^ γ$-norm of the forcing term with $γ>d/2$, and the $α/2$-moment of the exit time from $D$ of the Brownian motion. Secondly, we derive explicit estimates for the $α/2$-moment of the exit time in terms of the distance to the boundary, the regularity of the domain $D$, and $α$. Using this approach, we derive explicit estimates for the same problem in domains satisfying exterior ball conditions, respectively exterior cone/wedge conditions, in terms of simple geometric features. As a consequence we also obtain explicit constants for pointwise estimates for the Green function and for the gradient of the solution. The obtained estimates can be employed to bypass the curse of high dimensions when aiming to approximate the solution of the Poisson problem using neural networks, obtaining polynomial scaling with dimension, which in some cases can be shown to be optimal.
title Quantitative boundary Hölder estimates for the inhomogeneous Poisson problem through a probabilistic approach
topic Probability
Analysis of PDEs
url https://arxiv.org/abs/2510.06906