On the Convergence of FedProx with Extrapolation and Inexact Prox

Fuente: arXiv
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Autores principales: Li, Hanmin, Richtárik, Peter
Formato: Preprint
Publicado: 2024
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author Li, Hanmin
Richtárik, Peter
author_facet Li, Hanmin
Richtárik, Peter
contents Enhancing the FedProx federated learning algorithm (Li et al., 2020) with server-side extrapolation, Li et al. (2024a) recently introduced the FedExProx method. Their theoretical analysis, however, relies on the assumption that each client computes a certain proximal operator exactly, which is impractical since this is virtually never possible to do in real settings. In this paper, we investigate the behavior of FedExProx without this exactness assumption in the smooth and globally strongly convex setting. We establish a general convergence result, showing that inexactness leads to convergence to a neighborhood of the solution. Additionally, we demonstrate that, with careful control, the adverse effects of this inexactness can be mitigated. By linking inexactness to biased compression (Beznosikov et al., 2023), we refine our analysis, highlighting robustness of extrapolation to inexact proximal updates. We also examine the local iteration complexity required by each client to achieved the required level of inexactness using various local optimizers. Our theoretical insights are validated through comprehensive numerical experiments.
format Preprint
id arxiv_https___arxiv_org_abs_2410_01410
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle On the Convergence of FedProx with Extrapolation and Inexact Prox
Li, Hanmin
Richtárik, Peter
Optimization and Control
Artificial Intelligence
90C25
Enhancing the FedProx federated learning algorithm (Li et al., 2020) with server-side extrapolation, Li et al. (2024a) recently introduced the FedExProx method. Their theoretical analysis, however, relies on the assumption that each client computes a certain proximal operator exactly, which is impractical since this is virtually never possible to do in real settings. In this paper, we investigate the behavior of FedExProx without this exactness assumption in the smooth and globally strongly convex setting. We establish a general convergence result, showing that inexactness leads to convergence to a neighborhood of the solution. Additionally, we demonstrate that, with careful control, the adverse effects of this inexactness can be mitigated. By linking inexactness to biased compression (Beznosikov et al., 2023), we refine our analysis, highlighting robustness of extrapolation to inexact proximal updates. We also examine the local iteration complexity required by each client to achieved the required level of inexactness using various local optimizers. Our theoretical insights are validated through comprehensive numerical experiments.
title On the Convergence of FedProx with Extrapolation and Inexact Prox
topic Optimization and Control
Artificial Intelligence
90C25
url https://arxiv.org/abs/2410.01410