Byzantine-Robust Distributed SGD: A Unified Analysis and Tight Error Bounds

Fuente: arXiv
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Auteurs principaux: Ruan, Boyuan, Wang, Xiaoyu, Liu, Ya-Feng
Format: Preprint
Publié: 2026
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author Ruan, Boyuan
Wang, Xiaoyu
Liu, Ya-Feng
author_facet Ruan, Boyuan
Wang, Xiaoyu
Liu, Ya-Feng
contents Byzantine-robust distributed optimization relies on robust aggregation rules to mitigate the influence of malicious Byzantine workers. Despite the proliferation of such rules, a unified convergence analysis framework that accommodates general data heterogeneity is lacking. In this work, we provide a thorough convergence theory of Byzantine-robust distributed stochastic gradient descent (SGD), analyzing variants both with and without local momentum. We establish the convergence rates for nonconvex smooth objectives and those satisfying the Polyak-Lojasiewicz condition under a general data heterogeneity assumption. Our analysis reveals that while stochasticity and data heterogeneity introduce unavoidable error floors, local momentum provably reduces the error component induced by stochasticity. Furthermore, we derive matching lower bounds to demonstrate that the upper bounds obtained in our analysis are tight and characterize the fundamental limits of Byzantine resilience under stochasticity and data heterogeneity. Empirical results support our theoretical findings.
format Preprint
id arxiv_https___arxiv_org_abs_2604_10179
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Byzantine-Robust Distributed SGD: A Unified Analysis and Tight Error Bounds
Ruan, Boyuan
Wang, Xiaoyu
Liu, Ya-Feng
Optimization and Control
Machine Learning
Byzantine-robust distributed optimization relies on robust aggregation rules to mitigate the influence of malicious Byzantine workers. Despite the proliferation of such rules, a unified convergence analysis framework that accommodates general data heterogeneity is lacking. In this work, we provide a thorough convergence theory of Byzantine-robust distributed stochastic gradient descent (SGD), analyzing variants both with and without local momentum. We establish the convergence rates for nonconvex smooth objectives and those satisfying the Polyak-Lojasiewicz condition under a general data heterogeneity assumption. Our analysis reveals that while stochasticity and data heterogeneity introduce unavoidable error floors, local momentum provably reduces the error component induced by stochasticity. Furthermore, we derive matching lower bounds to demonstrate that the upper bounds obtained in our analysis are tight and characterize the fundamental limits of Byzantine resilience under stochasticity and data heterogeneity. Empirical results support our theoretical findings.
title Byzantine-Robust Distributed SGD: A Unified Analysis and Tight Error Bounds
topic Optimization and Control
Machine Learning
url https://arxiv.org/abs/2604.10179