AdaGrad under Anisotropic Smoothness

Fuente: arXiv
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Main Authors: Liu, Yuxing, Pan, Rui, Zhang, Tong
Format: Preprint
Published: 2024
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author Liu, Yuxing
Pan, Rui
Zhang, Tong
author_facet Liu, Yuxing
Pan, Rui
Zhang, Tong
contents Adaptive gradient methods have been widely adopted in training large-scale deep neural networks, especially large foundation models. Despite the huge success in practice, their theoretical advantages over classical gradient methods with uniform step sizes across all coordinates (e.g. SGD) have not been fully understood, especially in the large batch-size setting commonly used in practice. This is because the only theoretical result that can demonstrate this benefit was obtained in the original paper of Adagrad for convex nonsmooth objective functions, which is insufficient for large batch algorithms. In this work, we attempt to resolve this gap between theory and practice by proposing a novel anisotropic generalized smoothness assumption and providing corresponding analyses of Adagrad. It is shown that under anisotropic smoothness and noise conditions, AdaGrad can achieve faster convergence guarantees in terms of better dimensional dependence than algorithms with uniform step sizes across all coordinates. Experiments in logistic regression and instruction following fine-tuning tasks provide strong evidence to support our novel assumption and theoretical analysis.
format Preprint
id arxiv_https___arxiv_org_abs_2406_15244
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle AdaGrad under Anisotropic Smoothness
Liu, Yuxing
Pan, Rui
Zhang, Tong
Machine Learning
Optimization and Control
Adaptive gradient methods have been widely adopted in training large-scale deep neural networks, especially large foundation models. Despite the huge success in practice, their theoretical advantages over classical gradient methods with uniform step sizes across all coordinates (e.g. SGD) have not been fully understood, especially in the large batch-size setting commonly used in practice. This is because the only theoretical result that can demonstrate this benefit was obtained in the original paper of Adagrad for convex nonsmooth objective functions, which is insufficient for large batch algorithms. In this work, we attempt to resolve this gap between theory and practice by proposing a novel anisotropic generalized smoothness assumption and providing corresponding analyses of Adagrad. It is shown that under anisotropic smoothness and noise conditions, AdaGrad can achieve faster convergence guarantees in terms of better dimensional dependence than algorithms with uniform step sizes across all coordinates. Experiments in logistic regression and instruction following fine-tuning tasks provide strong evidence to support our novel assumption and theoretical analysis.
title AdaGrad under Anisotropic Smoothness
topic Machine Learning
Optimization and Control
url https://arxiv.org/abs/2406.15244