Faster Adaptive Optimization via Expected Gradient Outer Product Reparameterization

Fuente: arXiv
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Main Authors: DePavia, Adela, Cruzado, Jose, Liang, Jiayou, Charisopoulos, Vasileios, Willett, Rebecca
Format: Preprint
Published: 2025
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author DePavia, Adela
Cruzado, Jose
Liang, Jiayou
Charisopoulos, Vasileios
Willett, Rebecca
author_facet DePavia, Adela
Cruzado, Jose
Liang, Jiayou
Charisopoulos, Vasileios
Willett, Rebecca
contents Adaptive optimization algorithms -- such as Adagrad, Adam, and their variants -- have found widespread use in machine learning, signal processing and many other settings. Several methods in this family are not rotationally equivariant, meaning that simple reparameterizations (i.e. change of basis) can drastically affect their convergence. However, their sensitivity to the choice of parameterization has not been systematically studied; it is not clear how to identify a "favorable" change of basis in which these methods perform best. In this paper we propose a reparameterization method and demonstrate both theoretically and empirically its potential to improve their convergence behavior. Our method is an orthonormal transformation based on the expected gradient outer product (EGOP) matrix, which can be approximated using either full-batch or stochastic gradient oracles. We show that for a broad class of functions, the sensitivity of adaptive algorithms to choice-of-basis is influenced by the decay of the EGOP matrix spectrum. We illustrate the potential impact of EGOP reparameterization by presenting empirical evidence and theoretical arguments that common machine learning tasks with "natural" data exhibit EGOP spectral decay.
format Preprint
id arxiv_https___arxiv_org_abs_2502_01594
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Faster Adaptive Optimization via Expected Gradient Outer Product Reparameterization
DePavia, Adela
Cruzado, Jose
Liang, Jiayou
Charisopoulos, Vasileios
Willett, Rebecca
Machine Learning
Optimization and Control
90C06, 65K10, 90C30, 68T07
Adaptive optimization algorithms -- such as Adagrad, Adam, and their variants -- have found widespread use in machine learning, signal processing and many other settings. Several methods in this family are not rotationally equivariant, meaning that simple reparameterizations (i.e. change of basis) can drastically affect their convergence. However, their sensitivity to the choice of parameterization has not been systematically studied; it is not clear how to identify a "favorable" change of basis in which these methods perform best. In this paper we propose a reparameterization method and demonstrate both theoretically and empirically its potential to improve their convergence behavior. Our method is an orthonormal transformation based on the expected gradient outer product (EGOP) matrix, which can be approximated using either full-batch or stochastic gradient oracles. We show that for a broad class of functions, the sensitivity of adaptive algorithms to choice-of-basis is influenced by the decay of the EGOP matrix spectrum. We illustrate the potential impact of EGOP reparameterization by presenting empirical evidence and theoretical arguments that common machine learning tasks with "natural" data exhibit EGOP spectral decay.
title Faster Adaptive Optimization via Expected Gradient Outer Product Reparameterization
topic Machine Learning
Optimization and Control
90C06, 65K10, 90C30, 68T07
url https://arxiv.org/abs/2502.01594