Almost Sure Convergence Analysis of Differentially Private Stochastic Gradient Methods

Fuente: arXiv
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Hauptverfasser: Mukherjee, Amartya, Liu, Jun
Format: Preprint
Veröffentlicht: 2025
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author Mukherjee, Amartya
Liu, Jun
author_facet Mukherjee, Amartya
Liu, Jun
contents Differentially private stochastic gradient descent (DP-SGD) has become the standard algorithm for training machine learning models with rigorous privacy guarantees. Despite its widespread use, the theoretical understanding of its long-run behavior remains limited: existing analyses typically establish convergence in expectation or with high probability, but do not address the almost sure convergence of single trajectories. In this work, we prove that DP-SGD converges almost surely under standard smoothness assumptions, both in nonconvex and strongly convex settings, provided the step sizes satisfy some standard decaying conditions. Our analysis extends to momentum variants such as the stochastic heavy ball (DP-SHB) and Nesterov's accelerated gradient (DP-NAG), where we show that careful energy constructions yield similar guarantees. These results provide stronger theoretical foundations for differentially private optimization and suggest that, despite privacy-induced distortions, the algorithm remains pathwise stable in both convex and nonconvex regimes.
format Preprint
id arxiv_https___arxiv_org_abs_2511_16587
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Almost Sure Convergence Analysis of Differentially Private Stochastic Gradient Methods
Mukherjee, Amartya
Liu, Jun
Machine Learning
Optimization and Control
Differentially private stochastic gradient descent (DP-SGD) has become the standard algorithm for training machine learning models with rigorous privacy guarantees. Despite its widespread use, the theoretical understanding of its long-run behavior remains limited: existing analyses typically establish convergence in expectation or with high probability, but do not address the almost sure convergence of single trajectories. In this work, we prove that DP-SGD converges almost surely under standard smoothness assumptions, both in nonconvex and strongly convex settings, provided the step sizes satisfy some standard decaying conditions. Our analysis extends to momentum variants such as the stochastic heavy ball (DP-SHB) and Nesterov's accelerated gradient (DP-NAG), where we show that careful energy constructions yield similar guarantees. These results provide stronger theoretical foundations for differentially private optimization and suggest that, despite privacy-induced distortions, the algorithm remains pathwise stable in both convex and nonconvex regimes.
title Almost Sure Convergence Analysis of Differentially Private Stochastic Gradient Methods
topic Machine Learning
Optimization and Control
url https://arxiv.org/abs/2511.16587