Deep Equilibrium Models are Almost Equivalent to Not-so-deep Explicit Models for High-dimensional Gaussian Mixtures

Fuente: arXiv
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Auteurs principaux: Ling, Zenan, Li, Longbo, Feng, Zhanbo, Zhang, Yixuan, Zhou, Feng, Qiu, Robert C., Liao, Zhenyu
Format: Preprint
Publié: 2024
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author Ling, Zenan
Li, Longbo
Feng, Zhanbo
Zhang, Yixuan
Zhou, Feng
Qiu, Robert C.
Liao, Zhenyu
author_facet Ling, Zenan
Li, Longbo
Feng, Zhanbo
Zhang, Yixuan
Zhou, Feng
Qiu, Robert C.
Liao, Zhenyu
contents Deep equilibrium models (DEQs), as a typical implicit neural network, have demonstrated remarkable success on various tasks. There is, however, a lack of theoretical understanding of the connections and differences between implicit DEQs and explicit neural network models. In this paper, leveraging recent advances in random matrix theory (RMT), we perform an in-depth analysis on the eigenspectra of the conjugate kernel (CK) and neural tangent kernel (NTK) matrices for implicit DEQs, when the input data are drawn from a high-dimensional Gaussian mixture. We prove, in this setting, that the spectral behavior of these Implicit-CKs and NTKs depend on the DEQ activation function and initial weight variances, but only via a system of four nonlinear equations. As a direct consequence of this theoretical result, we demonstrate that a shallow explicit network can be carefully designed to produce the same CK or NTK as a given DEQ. Despite derived here for Gaussian mixture data, empirical results show the proposed theory and design principle also apply to popular real-world datasets.
format Preprint
id arxiv_https___arxiv_org_abs_2402_02697
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Deep Equilibrium Models are Almost Equivalent to Not-so-deep Explicit Models for High-dimensional Gaussian Mixtures
Ling, Zenan
Li, Longbo
Feng, Zhanbo
Zhang, Yixuan
Zhou, Feng
Qiu, Robert C.
Liao, Zhenyu
Machine Learning
Deep equilibrium models (DEQs), as a typical implicit neural network, have demonstrated remarkable success on various tasks. There is, however, a lack of theoretical understanding of the connections and differences between implicit DEQs and explicit neural network models. In this paper, leveraging recent advances in random matrix theory (RMT), we perform an in-depth analysis on the eigenspectra of the conjugate kernel (CK) and neural tangent kernel (NTK) matrices for implicit DEQs, when the input data are drawn from a high-dimensional Gaussian mixture. We prove, in this setting, that the spectral behavior of these Implicit-CKs and NTKs depend on the DEQ activation function and initial weight variances, but only via a system of four nonlinear equations. As a direct consequence of this theoretical result, we demonstrate that a shallow explicit network can be carefully designed to produce the same CK or NTK as a given DEQ. Despite derived here for Gaussian mixture data, empirical results show the proposed theory and design principle also apply to popular real-world datasets.
title Deep Equilibrium Models are Almost Equivalent to Not-so-deep Explicit Models for High-dimensional Gaussian Mixtures
topic Machine Learning
url https://arxiv.org/abs/2402.02697