The Field Equations of Penalized non-Parametric Regression

Fuente: arXiv
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Main Author: Pappert, Sven
Format: Preprint
Published: 2025
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author Pappert, Sven
author_facet Pappert, Sven
contents We view penalized risks through the lens of the calculus of variations. We consider risks comprised of a fitness-term (e.g. MSE) and a gradient-based penalty. After establishing the Euler-Lagrange field equations as a systematic approach to finding minimizers of risks involving only first derivatives, we proceed to exemplify this approach to the MSE penalized by the integral over the squared l2-norm of the gradient of the regression function. The minimizer of this risk is given as the solution to a second order inhomogeneous PDE, where the inhomogeneity is given as the conditional expectation of the target variable conditioned on the features. We discuss properties of the field equations and practical implications thereof, which also apply to the classical Ridge penalty for linear models, and embed our findings into the existing literature. In particular, we find that we can recover the Rudin-Osher-Fatemi model for image-denoising, if we consider the features as deterministic and evenly distributed. Last, we outline several directions for future research.
format Preprint
id arxiv_https___arxiv_org_abs_2503_14763
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The Field Equations of Penalized non-Parametric Regression
Pappert, Sven
Statistics Theory
Analysis of PDEs
Functional Analysis
We view penalized risks through the lens of the calculus of variations. We consider risks comprised of a fitness-term (e.g. MSE) and a gradient-based penalty. After establishing the Euler-Lagrange field equations as a systematic approach to finding minimizers of risks involving only first derivatives, we proceed to exemplify this approach to the MSE penalized by the integral over the squared l2-norm of the gradient of the regression function. The minimizer of this risk is given as the solution to a second order inhomogeneous PDE, where the inhomogeneity is given as the conditional expectation of the target variable conditioned on the features. We discuss properties of the field equations and practical implications thereof, which also apply to the classical Ridge penalty for linear models, and embed our findings into the existing literature. In particular, we find that we can recover the Rudin-Osher-Fatemi model for image-denoising, if we consider the features as deterministic and evenly distributed. Last, we outline several directions for future research.
title The Field Equations of Penalized non-Parametric Regression
topic Statistics Theory
Analysis of PDEs
Functional Analysis
url https://arxiv.org/abs/2503.14763