Second-Order Convergence in Private Stochastic Non-Convex Optimization

Fuente: arXiv
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Autores principales: Tao, Youming, Zhang, Zuyuan, Yu, Dongxiao, Cheng, Xiuzhen, Dressler, Falko, Wang, Di
Formato: Preprint
Publicado: 2025
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author Tao, Youming
Zhang, Zuyuan
Yu, Dongxiao
Cheng, Xiuzhen
Dressler, Falko
Wang, Di
author_facet Tao, Youming
Zhang, Zuyuan
Yu, Dongxiao
Cheng, Xiuzhen
Dressler, Falko
Wang, Di
contents We investigate the problem of finding second-order stationary points (SOSP) in differentially private (DP) stochastic non-convex optimization. Existing methods suffer from two key limitations: (i) inaccurate convergence error rate due to overlooking gradient variance in the saddle point escape analysis, and (ii) dependence on auxiliary private model selection procedures for identifying DP-SOSP, which can significantly impair utility, particularly in distributed settings. To address these issues, we propose a generic perturbed stochastic gradient descent (PSGD) framework built upon Gaussian noise injection and general gradient oracles. A core innovation of our framework is using model drift distance to determine whether PSGD escapes saddle points, ensuring convergence to approximate local minima without relying on second-order information or additional DP-SOSP identification. By leveraging the adaptive DP-SPIDER estimator as a specific gradient oracle, we develop a new DP algorithm that rectifies the convergence error rates reported in prior work. We further extend this algorithm to distributed learning with heterogeneous data, providing the first formal guarantees for finding DP-SOSP in such settings. Our analysis also highlights the detrimental impacts of private selection procedures in distributed learning under high-dimensional models, underscoring the practical benefits of our design. Numerical experiments on real-world datasets validate the efficacy of our approach.
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id arxiv_https___arxiv_org_abs_2505_15647
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Second-Order Convergence in Private Stochastic Non-Convex Optimization
Tao, Youming
Zhang, Zuyuan
Yu, Dongxiao
Cheng, Xiuzhen
Dressler, Falko
Wang, Di
Machine Learning
Artificial Intelligence
We investigate the problem of finding second-order stationary points (SOSP) in differentially private (DP) stochastic non-convex optimization. Existing methods suffer from two key limitations: (i) inaccurate convergence error rate due to overlooking gradient variance in the saddle point escape analysis, and (ii) dependence on auxiliary private model selection procedures for identifying DP-SOSP, which can significantly impair utility, particularly in distributed settings. To address these issues, we propose a generic perturbed stochastic gradient descent (PSGD) framework built upon Gaussian noise injection and general gradient oracles. A core innovation of our framework is using model drift distance to determine whether PSGD escapes saddle points, ensuring convergence to approximate local minima without relying on second-order information or additional DP-SOSP identification. By leveraging the adaptive DP-SPIDER estimator as a specific gradient oracle, we develop a new DP algorithm that rectifies the convergence error rates reported in prior work. We further extend this algorithm to distributed learning with heterogeneous data, providing the first formal guarantees for finding DP-SOSP in such settings. Our analysis also highlights the detrimental impacts of private selection procedures in distributed learning under high-dimensional models, underscoring the practical benefits of our design. Numerical experiments on real-world datasets validate the efficacy of our approach.
title Second-Order Convergence in Private Stochastic Non-Convex Optimization
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2505.15647