Analysis of Decentralized Stochastic Successive Convex Approximation for composite non-convex problems

Fuente: arXiv
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Auteurs principaux: Idrees, Basil M., Sharma, Shivangi Dubey, Rajawat, Ketan
Format: Preprint
Publié: 2024
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author Idrees, Basil M.
Sharma, Shivangi Dubey
Rajawat, Ketan
author_facet Idrees, Basil M.
Sharma, Shivangi Dubey
Rajawat, Ketan
contents This work considers the decentralized successive convex approximation (SCA) method for minimizing stochastic non-convex objectives subject to convex constraints, along with possibly non-smooth convex regularizers. Although SCA has been widely applied in decentralized settings, its stochastic first order (SFO) complexity is unknown, and it is thought to be slower than the centralized momentum-enhanced SCA variants. In this work, we advance the state-of-the-art for SCA methods by proposing an accelerated variant, namely the \textbf{D}ecentralized \textbf{M}omentum-based \textbf{S}tochastic \textbf{SCA} (\textbf{D-MSSCA}) and analyze its SFO complexity. The proposed algorithm entails creating a stochastic surrogate of the objective at every iteration, which is minimized at each node separately. Remarkably, the D-MSSCA achieves an SFO complexity of $\mathcal{O}(ε^{-3/2})$ to reach an $ε$-stationary point, which is at par with the SFO complexity lower bound for unconstrained stochastic non-convex optimization in centralized setting.
format Preprint
id arxiv_https___arxiv_org_abs_2405_07100
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Analysis of Decentralized Stochastic Successive Convex Approximation for composite non-convex problems
Idrees, Basil M.
Sharma, Shivangi Dubey
Rajawat, Ketan
Optimization and Control
Signal Processing
This work considers the decentralized successive convex approximation (SCA) method for minimizing stochastic non-convex objectives subject to convex constraints, along with possibly non-smooth convex regularizers. Although SCA has been widely applied in decentralized settings, its stochastic first order (SFO) complexity is unknown, and it is thought to be slower than the centralized momentum-enhanced SCA variants. In this work, we advance the state-of-the-art for SCA methods by proposing an accelerated variant, namely the \textbf{D}ecentralized \textbf{M}omentum-based \textbf{S}tochastic \textbf{SCA} (\textbf{D-MSSCA}) and analyze its SFO complexity. The proposed algorithm entails creating a stochastic surrogate of the objective at every iteration, which is minimized at each node separately. Remarkably, the D-MSSCA achieves an SFO complexity of $\mathcal{O}(ε^{-3/2})$ to reach an $ε$-stationary point, which is at par with the SFO complexity lower bound for unconstrained stochastic non-convex optimization in centralized setting.
title Analysis of Decentralized Stochastic Successive Convex Approximation for composite non-convex problems
topic Optimization and Control
Signal Processing
url https://arxiv.org/abs/2405.07100