arXiv subjects

Longkang Zhu

Publications and source records attributed to Longkang Zhu.

3 recordsLinked to original sources

arXiv2025

Distributed Online Randomized Gradient-Free Optimization with Compressed Communication

This paper addresses two fundamental challenges in distributed online convex optimization: communication efficiency and optimization under limited feedback. We propose a unified framework named Online Compressed Gradient Tracking (OCGT), which includes two variants: One-point Bandit Feedback (OCGT-BF) and Stochastic Gradient Feedback (OCSGT). The proposed algorithms harness data compression and either gradient-free or stochastic gradient optimization techniques within distributed networks. The proposed framework incorporates a compression scheme with error compensation mechanisms to reduce communication overhead while maintaining convergence guarantees. Unlike traditional approaches that assume perfect communication and full gradient access, OCGT operates effectively under practical constraints by combining gradient-like tracking with one-point or stochastic gradient feedback estimation. We provide a theoretical analysis demonstrating dynamic regret bounds for both variants. Finally, extensive experiments validate that OCGT achieves low dynamic regret while significantly reducing communication requirements.

math.OC↗

arXiv2025

A Hybrid Stochastic Gradient Tracking Method for Distributed Online Optimization Over Time-Varying Directed Networks

With the increasing scale and dynamics of data, distributed online optimization has become essential for real-time decision-making in various applications. However, existing algorithms often rely on bounded gradient assumptions and overlook the impact of stochastic gradients, especially in time-varying directed networks. This study proposes a novel Time-Varying Hybrid Stochastic Gradient Tracking algorithm named TV-HSGT, based on hybrid stochastic gradient tracking and variance reduction mechanisms. Specifically, TV-HSGT integrates row-stochastic and column-stochastic communication schemes over time-varying digraphs, eliminating the need for Perron vector estimation or out-degree information. By combining current and recursive stochastic gradients, it effectively reduces gradient variance while accurately tracking global descent directions. Theoretical analysis demonstrates that TV-HSGT can achieve improved bounds on dynamic regret without assuming gradient boundedness. Experimental results on logistic regression tasks confirm the effectiveness of TV-HSGT in dynamic and resource-constrained environments.

cs.LG↗

arXiv2025

Distributed Online Randomized Gradient-Free optimization with Compressed Communication

This paper addresses two fundamental challenges in distributed online convex optimization: communication efficiency and optimization under limited feedback. We propose Online Compressed Gradient Tracking with one-point Bandit Feedback (OCGT-BF), a novel algorithm that harness data compression and gradient-free optimization techniques in distributed networks. Our algorithm incorporates a compression scheme with error compensation mechanisms to reduce communication overhead while maintaining convergence guarantees. Unlike traditional approaches that assume perfect communication and full gradient access, OCGT-BF operates effectively under practical constraints by combining gradient-like tracking with one-point feedback estimation. We provide theoretical analysis demonstrating the dynamic regret bounds under both bandit feedback and stochastic gradient scenarios. Finally, extensive experiments validate that OCGT-BF achieves low dynamic regret while significantly reducing communication requirements.

math.OC↗