Convergence Rates for the Maximum A Posteriori Estimator in PDE-Regression Models with Random Design

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Auteur principal: Siebel, Maximilian
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Publié: 2024
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author Siebel, Maximilian
author_facet Siebel, Maximilian
contents We consider the statistical inverse problem of recovering a parameter $θ\in H^α$ from data arising from the Gaussian regression problem \begin{equation*} Y = \mathscr{G}(θ)(Z)+\varepsilon \end{equation*} with nonlinear forward map $\mathscr{G}:\mathbb{L}^2\to\mathbb{L}^2$, random design points $Z$ and Gaussian noise $\varepsilon$. The estimation strategy is based on a least squares approach under $\Vert\cdot\Vert_{H^α}$-constraints. We establish the existence of a least squares estimator $\hatθ$ as a maximizer for a given functional under Lipschitz-type assumptions on the forward map $\mathscr{G}$. A general concentration result is shown, which is used to prove consistency and upper bounds for the prediction error. The corresponding rates of convergence reflect not only the smoothness of the parameter of interest but also the ill-posedness of the underlying inverse problem. We apply the general model to the Darcy problem, where the recovery of an unknown coefficient function $f$ of a PDE is of interest. For this example, we also provide corresponding rates of convergence for the prediction and estimation errors. Additionally, we briefly discuss the applicability of the general model to other problems.
format Preprint
id arxiv_https___arxiv_org_abs_2409_03417
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Convergence Rates for the Maximum A Posteriori Estimator in PDE-Regression Models with Random Design
Siebel, Maximilian
Statistics Theory
62G05, 35R30
We consider the statistical inverse problem of recovering a parameter $θ\in H^α$ from data arising from the Gaussian regression problem \begin{equation*} Y = \mathscr{G}(θ)(Z)+\varepsilon \end{equation*} with nonlinear forward map $\mathscr{G}:\mathbb{L}^2\to\mathbb{L}^2$, random design points $Z$ and Gaussian noise $\varepsilon$. The estimation strategy is based on a least squares approach under $\Vert\cdot\Vert_{H^α}$-constraints. We establish the existence of a least squares estimator $\hatθ$ as a maximizer for a given functional under Lipschitz-type assumptions on the forward map $\mathscr{G}$. A general concentration result is shown, which is used to prove consistency and upper bounds for the prediction error. The corresponding rates of convergence reflect not only the smoothness of the parameter of interest but also the ill-posedness of the underlying inverse problem. We apply the general model to the Darcy problem, where the recovery of an unknown coefficient function $f$ of a PDE is of interest. For this example, we also provide corresponding rates of convergence for the prediction and estimation errors. Additionally, we briefly discuss the applicability of the general model to other problems.
title Convergence Rates for the Maximum A Posteriori Estimator in PDE-Regression Models with Random Design
topic Statistics Theory
62G05, 35R30
url https://arxiv.org/abs/2409.03417