A Historical Trajectory Assisted Optimization Method for Zeroth-Order Federated Learning

Fuente: arXiv
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Autori principali: Wu, Chenlin, He, Xiaoyu, Li, Zike, Gong, Jing, Zheng, Zibin
Natura: Preprint
Pubblicazione: 2024
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author Wu, Chenlin
He, Xiaoyu
Li, Zike
Gong, Jing
Zheng, Zibin
author_facet Wu, Chenlin
He, Xiaoyu
Li, Zike
Gong, Jing
Zheng, Zibin
contents Federated learning heavily relies on distributed gradient descent techniques. In the situation where gradient information is not available, the gradients need to be estimated from zeroth-order information, which typically involves computing finite-differences along isotropic random directions. This method suffers from high estimation errors, as the geometric features of the objective landscape may be overlooked during the isotropic sampling. In this work, we propose a non-isotropic sampling method to improve the gradient estimation procedure. Gradients in our method are estimated in a subspace spanned by historical trajectories of solutions, aiming to encourage the exploration of promising regions and hence improve the convergence. The proposed method uses a covariance matrix for sampling which is a convex combination of two parts. The first part is a thin projection matrix containing the basis of the subspace which is designed to improve the exploitation ability. The second part is the historical trajectories. We implement this method in zeroth-order federated settings, and show that the convergence rate aligns with existing ones while introducing no significant overheads in communication or local computation. The effectiveness of our proposal is verified on several numerical experiments in comparison to several commonly-used zeroth-order federated optimization algorithms.
format Preprint
id arxiv_https___arxiv_org_abs_2409_15955
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle A Historical Trajectory Assisted Optimization Method for Zeroth-Order Federated Learning
Wu, Chenlin
He, Xiaoyu
Li, Zike
Gong, Jing
Zheng, Zibin
Machine Learning
Artificial Intelligence
Federated learning heavily relies on distributed gradient descent techniques. In the situation where gradient information is not available, the gradients need to be estimated from zeroth-order information, which typically involves computing finite-differences along isotropic random directions. This method suffers from high estimation errors, as the geometric features of the objective landscape may be overlooked during the isotropic sampling. In this work, we propose a non-isotropic sampling method to improve the gradient estimation procedure. Gradients in our method are estimated in a subspace spanned by historical trajectories of solutions, aiming to encourage the exploration of promising regions and hence improve the convergence. The proposed method uses a covariance matrix for sampling which is a convex combination of two parts. The first part is a thin projection matrix containing the basis of the subspace which is designed to improve the exploitation ability. The second part is the historical trajectories. We implement this method in zeroth-order federated settings, and show that the convergence rate aligns with existing ones while introducing no significant overheads in communication or local computation. The effectiveness of our proposal is verified on several numerical experiments in comparison to several commonly-used zeroth-order federated optimization algorithms.
title A Historical Trajectory Assisted Optimization Method for Zeroth-Order Federated Learning
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2409.15955