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Main Authors: Kumar, Akash, Parhi, Rahul, Belkin, Mikhail
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2502.16331
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author Kumar, Akash
Parhi, Rahul
Belkin, Mikhail
author_facet Kumar, Akash
Parhi, Rahul
Belkin, Mikhail
contents Recent works have characterized the function-space inductive bias of infinite-width bounded-norm single-hidden-layer neural networks as a kind of bounded-variation-type space. This novel neural network Banach space encompasses many classical multivariate function spaces, including certain Sobolev spaces and the spectral Barron spaces. Notably, this Banach space also includes functions that exhibit less classical regularity, such as those that only vary in a few directions. On bounded domains, it is well-established that the Gaussian reproducing kernel Hilbert space (RKHS) strictly embeds into this Banach space, demonstrating a clear gap between the Gaussian RKHS and the neural network Banach space. It turns out that when investigating these spaces on unbounded domains, e.g., all of $\mathbb{R}^d$, the story is fundamentally different. We establish the following fundamental result: Certain functions that lie in the Gaussian RKHS have infinite norm in the neural network Banach space. This provides a nontrivial gap between kernel methods and neural networks by exhibiting functions that kernel methods easily represent, whereas neural networks cannot.
format Preprint
id arxiv_https___arxiv_org_abs_2502_16331
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle A Gap Between the Gaussian RKHS and Neural Networks: An Infinite-Center Asymptotic Analysis
Kumar, Akash
Parhi, Rahul
Belkin, Mikhail
Machine Learning
Artificial Intelligence
Recent works have characterized the function-space inductive bias of infinite-width bounded-norm single-hidden-layer neural networks as a kind of bounded-variation-type space. This novel neural network Banach space encompasses many classical multivariate function spaces, including certain Sobolev spaces and the spectral Barron spaces. Notably, this Banach space also includes functions that exhibit less classical regularity, such as those that only vary in a few directions. On bounded domains, it is well-established that the Gaussian reproducing kernel Hilbert space (RKHS) strictly embeds into this Banach space, demonstrating a clear gap between the Gaussian RKHS and the neural network Banach space. It turns out that when investigating these spaces on unbounded domains, e.g., all of $\mathbb{R}^d$, the story is fundamentally different. We establish the following fundamental result: Certain functions that lie in the Gaussian RKHS have infinite norm in the neural network Banach space. This provides a nontrivial gap between kernel methods and neural networks by exhibiting functions that kernel methods easily represent, whereas neural networks cannot.
title A Gap Between the Gaussian RKHS and Neural Networks: An Infinite-Center Asymptotic Analysis
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2502.16331