Improved Convergence for Decentralized Stochastic Optimization with Biased Gradients

Fuente: arXiv
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Hauptverfasser: Xu, Qing, Liao, Yiwei, Fan, Wenqi, You, Xingxing, Dian, Songyi
Format: Preprint
Veröffentlicht: 2026
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author Xu, Qing
Liao, Yiwei
Fan, Wenqi
You, Xingxing
Dian, Songyi
author_facet Xu, Qing
Liao, Yiwei
Fan, Wenqi
You, Xingxing
Dian, Songyi
contents Decentralized stochastic optimization has emerged as a fundamental paradigm for large-scale machine learning. However, practical implementations often rely on biased gradient estimators arising from communication compression or inexact local oracles, which severely degrade convergence in the presence of data heterogeneity. To address the challenge, we propose Decentralized Momentum Tracking with Biased Gradients (Biased-DMT), a novel decentralized algorithm designed to operate reliably under biased gradient information. We establish a comprehensive convergence theory for Biased-DMT in nonconvex settings and show that it achieves linear speedup with respect to the number of agents. The theoretical analysis shows that Biased-DMT decouples the effects of network topology from data heterogeneity, enabling robust performance even in sparse communication networks. Notably, when the gradient oracle introduces only absolute bias, the proposed method eliminates the structural heterogeneity error and converges to the exact physical error floor. For the case of relative bias, we further characterize the convergence limit and show that the remaining error is an unavoidable physical consequence of locally injected noise. Extensive numerical experiments corroborate our theoretical analysis and demonstrate the practical effectiveness of Biased-DMT across a range of decentralized learning scenarios.
format Preprint
id arxiv_https___arxiv_org_abs_2604_08236
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Improved Convergence for Decentralized Stochastic Optimization with Biased Gradients
Xu, Qing
Liao, Yiwei
Fan, Wenqi
You, Xingxing
Dian, Songyi
Optimization and Control
Decentralized stochastic optimization has emerged as a fundamental paradigm for large-scale machine learning. However, practical implementations often rely on biased gradient estimators arising from communication compression or inexact local oracles, which severely degrade convergence in the presence of data heterogeneity. To address the challenge, we propose Decentralized Momentum Tracking with Biased Gradients (Biased-DMT), a novel decentralized algorithm designed to operate reliably under biased gradient information. We establish a comprehensive convergence theory for Biased-DMT in nonconvex settings and show that it achieves linear speedup with respect to the number of agents. The theoretical analysis shows that Biased-DMT decouples the effects of network topology from data heterogeneity, enabling robust performance even in sparse communication networks. Notably, when the gradient oracle introduces only absolute bias, the proposed method eliminates the structural heterogeneity error and converges to the exact physical error floor. For the case of relative bias, we further characterize the convergence limit and show that the remaining error is an unavoidable physical consequence of locally injected noise. Extensive numerical experiments corroborate our theoretical analysis and demonstrate the practical effectiveness of Biased-DMT across a range of decentralized learning scenarios.
title Improved Convergence for Decentralized Stochastic Optimization with Biased Gradients
topic Optimization and Control
url https://arxiv.org/abs/2604.08236