Global law of conjugate kernel random matrices with heavy-tailed weights

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Hauptverfasser: Guionnet, Alice, Piccolo, Vanessa
Format: Preprint
Veröffentlicht: 2025
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author Guionnet, Alice
Piccolo, Vanessa
author_facet Guionnet, Alice
Piccolo, Vanessa
contents We study the asymptotic spectral distribution of the conjugate kernel random matrix $YY^\top$, where $Y= f(WX)$ arises from a two-layer neural network model. We consider the setting where $W$ and $X$ are random rectangular matrices with i.i.d.\ entries, where the entries of $W$ follow a heavy-tailed distribution, while those of $X$ have light tails. Our assumptions on $W$ include a broad class of heavy-tailed distributions, such as symmetric $α$-stable laws with $α\in ]0,2[$ and sparse matrices with $\mathcal{O}(1)$ nonzero entries per row. The activation function $f$, applied entrywise, is bounded, smooth, odd, and nonlinear. We compute the limiting eigenvalue distribution of $YY^\top$ through its moments and show that heavy-tailed weights induce strong correlations between the entries of $Y$, resulting in richer and fundamentally different spectral behavior compared to the light-tailed case.
format Preprint
id arxiv_https___arxiv_org_abs_2502_18428
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Global law of conjugate kernel random matrices with heavy-tailed weights
Guionnet, Alice
Piccolo, Vanessa
Probability
Machine Learning
60B20, 15B52, 68T07
We study the asymptotic spectral distribution of the conjugate kernel random matrix $YY^\top$, where $Y= f(WX)$ arises from a two-layer neural network model. We consider the setting where $W$ and $X$ are random rectangular matrices with i.i.d.\ entries, where the entries of $W$ follow a heavy-tailed distribution, while those of $X$ have light tails. Our assumptions on $W$ include a broad class of heavy-tailed distributions, such as symmetric $α$-stable laws with $α\in ]0,2[$ and sparse matrices with $\mathcal{O}(1)$ nonzero entries per row. The activation function $f$, applied entrywise, is bounded, smooth, odd, and nonlinear. We compute the limiting eigenvalue distribution of $YY^\top$ through its moments and show that heavy-tailed weights induce strong correlations between the entries of $Y$, resulting in richer and fundamentally different spectral behavior compared to the light-tailed case.
title Global law of conjugate kernel random matrices with heavy-tailed weights
topic Probability
Machine Learning
60B20, 15B52, 68T07
url https://arxiv.org/abs/2502.18428