Stochastic Gradient Descent with Momentum is Algorithmically Stable

Fuente: arXiv
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Main Authors: Lei, Yunwen, Wang, Zimeng, Yuan, Xiaoming
Format: Preprint
Published: 2026
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author Lei, Yunwen
Wang, Zimeng
Yuan, Xiaoming
author_facet Lei, Yunwen
Wang, Zimeng
Yuan, Xiaoming
contents Stochastic gradient descent with momentum (SGDM) is one of the most widely used optimization algorithms in machine learning. While optimization properties of SGDM have been extensively studied in the literature, it remains insufficiently understood whether and when SGDM can generalize well to unseen data. In particular, it has been conjectured that while momentum accelerates training, it may degrade generalization. In this paper, we close this gap by developing a comprehensive generalization analysis of SGDM through the lens of algorithmic stability. More specifically, we introduce a generalized SGDM framework that encompasses both Polyak's and Nesterov's momentum schemes, and establish tight on-average model stability bounds for smooth and convex problems. Notably, the obtained bounds exploit small optimization error bounds along the trajectory, apply to any momentum parameter in the interval $[0, 1)$, and do not require the commonly assumed Lipschitzness of loss functions. We further derive optimization error bounds for the generalized SGDM, and combine them with our generalization analyses to obtain optimal excess population risk bounds for SGDM with both Polyak's and Nesterov's momentum.
format Preprint
id arxiv_https___arxiv_org_abs_2605_28517
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Stochastic Gradient Descent with Momentum is Algorithmically Stable
Lei, Yunwen
Wang, Zimeng
Yuan, Xiaoming
Machine Learning
Artificial Intelligence
Stochastic gradient descent with momentum (SGDM) is one of the most widely used optimization algorithms in machine learning. While optimization properties of SGDM have been extensively studied in the literature, it remains insufficiently understood whether and when SGDM can generalize well to unseen data. In particular, it has been conjectured that while momentum accelerates training, it may degrade generalization. In this paper, we close this gap by developing a comprehensive generalization analysis of SGDM through the lens of algorithmic stability. More specifically, we introduce a generalized SGDM framework that encompasses both Polyak's and Nesterov's momentum schemes, and establish tight on-average model stability bounds for smooth and convex problems. Notably, the obtained bounds exploit small optimization error bounds along the trajectory, apply to any momentum parameter in the interval $[0, 1)$, and do not require the commonly assumed Lipschitzness of loss functions. We further derive optimization error bounds for the generalized SGDM, and combine them with our generalization analyses to obtain optimal excess population risk bounds for SGDM with both Polyak's and Nesterov's momentum.
title Stochastic Gradient Descent with Momentum is Algorithmically Stable
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2605.28517