Revisiting Stochastic Gradient Descent for Strongly Convex Objectives: Tight Uniform-in-Time Bounds

Fuente: arXiv
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Autores principales: Chen, Kang, Feng, Yasong, Wang, Tianyu
Formato: Preprint
Publicado: 2025
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author Chen, Kang
Feng, Yasong
Wang, Tianyu
author_facet Chen, Kang
Feng, Yasong
Wang, Tianyu
contents Stochastic optimization via Stochastic Gradient Descent (SGD) is a fundamental problem in statistics and optimization. This paper revisits Stochastic Gradient Descent (SGD) for strongly convex objectives, establishing tight, uniform-in-time convergence bounds. We prove that, with probability at least $1 - β$, a convergence rate of order $\frac{\log \log k + \log (1/β)}{k}$ simultaneously holds for all $ k \in \mathbb{N}_+ $, and demonstrate this bound is tight up to constant factors. We also provide an improved last-iterate convergence rate for such objectives. While focused on strongly convex objectives, our results generalize to the Polyak-Łojasiewicz functions and indicate an $\mathcal{O}(k^{-1} \log \log k)$ convergence rate for contractive stochastic approximation with additive noise.
format Preprint
id arxiv_https___arxiv_org_abs_2508_20823
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Revisiting Stochastic Gradient Descent for Strongly Convex Objectives: Tight Uniform-in-Time Bounds
Chen, Kang
Feng, Yasong
Wang, Tianyu
Optimization and Control
Stochastic optimization via Stochastic Gradient Descent (SGD) is a fundamental problem in statistics and optimization. This paper revisits Stochastic Gradient Descent (SGD) for strongly convex objectives, establishing tight, uniform-in-time convergence bounds. We prove that, with probability at least $1 - β$, a convergence rate of order $\frac{\log \log k + \log (1/β)}{k}$ simultaneously holds for all $ k \in \mathbb{N}_+ $, and demonstrate this bound is tight up to constant factors. We also provide an improved last-iterate convergence rate for such objectives. While focused on strongly convex objectives, our results generalize to the Polyak-Łojasiewicz functions and indicate an $\mathcal{O}(k^{-1} \log \log k)$ convergence rate for contractive stochastic approximation with additive noise.
title Revisiting Stochastic Gradient Descent for Strongly Convex Objectives: Tight Uniform-in-Time Bounds
topic Optimization and Control
url https://arxiv.org/abs/2508.20823