Multi-Timescale Primal Dual Hybrid Gradient with Application to Distributed Optimization

Fuente: arXiv
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Autori principali: Zhang, Junhui, Jaillet, Patrick
Natura: Preprint
Pubblicazione: 2025
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author Zhang, Junhui
Jaillet, Patrick
author_facet Zhang, Junhui
Jaillet, Patrick
contents We propose two variants of the Primal Dual Hybrid Gradient (PDHG) algorithm for saddle point problems with block decomposable duals, hereafter called Multi-Timescale PDHG (MT-PDHG) and its accelerated variant (AMT-PDHG). Through novel mixtures of Bregman divergence and multi-timescale extrapolations, our MT-PDHG and AMT-PDHG converge under arbitrary updating rates for different dual blocks while remaining fully deterministic and robust to extreme delays in dual updates. We further apply our (A)MT-PDHG, augmented with the gradient sliding techniques introduced in Lan et al. (2020), Lan (2016), to distributed optimization. The flexibility in choosing different updating rates for different blocks allows a more refined control over the communication rounds between different pairs of agents, thereby improving the efficiencies in settings with heterogeneity in local objectives and communication costs. Moreover, with careful choices of penalty levels, our algorithms show linear and thus optimal dependency on function similarities, a measure of how similar the gradients of local objectives are. This provides a positive answer to the open question whether such dependency is achievable for non-smooth objectives (Arjevani and Shamir 2015).
format Preprint
id arxiv_https___arxiv_org_abs_2506_15387
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Multi-Timescale Primal Dual Hybrid Gradient with Application to Distributed Optimization
Zhang, Junhui
Jaillet, Patrick
Optimization and Control
Machine Learning
We propose two variants of the Primal Dual Hybrid Gradient (PDHG) algorithm for saddle point problems with block decomposable duals, hereafter called Multi-Timescale PDHG (MT-PDHG) and its accelerated variant (AMT-PDHG). Through novel mixtures of Bregman divergence and multi-timescale extrapolations, our MT-PDHG and AMT-PDHG converge under arbitrary updating rates for different dual blocks while remaining fully deterministic and robust to extreme delays in dual updates. We further apply our (A)MT-PDHG, augmented with the gradient sliding techniques introduced in Lan et al. (2020), Lan (2016), to distributed optimization. The flexibility in choosing different updating rates for different blocks allows a more refined control over the communication rounds between different pairs of agents, thereby improving the efficiencies in settings with heterogeneity in local objectives and communication costs. Moreover, with careful choices of penalty levels, our algorithms show linear and thus optimal dependency on function similarities, a measure of how similar the gradients of local objectives are. This provides a positive answer to the open question whether such dependency is achievable for non-smooth objectives (Arjevani and Shamir 2015).
title Multi-Timescale Primal Dual Hybrid Gradient with Application to Distributed Optimization
topic Optimization and Control
Machine Learning
url https://arxiv.org/abs/2506.15387