S2O: Enhancing Adversarial Training with Second-Order Statistics of Weights

Fuente: arXiv
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Main Authors: Jin, Gaojie, Yi, Xinping, Huang, Wei, Schewe, Sven, Huang, Xiaowei
Format: Preprint
Published: 2026
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author Jin, Gaojie
Yi, Xinping
Huang, Wei
Schewe, Sven
Huang, Xiaowei
author_facet Jin, Gaojie
Yi, Xinping
Huang, Wei
Schewe, Sven
Huang, Xiaowei
contents Adversarial training has emerged as a highly effective way to improve the robustness of deep neural networks (DNNs). It is typically conceptualized as a min-max optimization problem over model weights and adversarial perturbations, where the weights are optimized using gradient descent methods, such as SGD. In this paper, we propose a novel approach by treating model weights as random variables, which paves the way for enhancing adversarial training through \textbf{S}econd-Order \textbf{S}tatistics \textbf{O}ptimization (S$^2$O) over model weights. We challenge and relax a prevalent, yet often unrealistic, assumption in prior PAC-Bayesian frameworks: the statistical independence of weights. From this relaxation, we derive an improved PAC-Bayesian robust generalization bound. Our theoretical developments suggest that optimizing the second-order statistics of weights can substantially tighten this bound. We complement this theoretical insight by conducting an extensive set of experiments that demonstrate that S$^2$O not only enhances the robustness and generalization of neural networks when used in isolation, but also seamlessly augments other state-of-the-art adversarial training techniques. The code is available at https://github.com/Alexkael/S2O.
format Preprint
id arxiv_https___arxiv_org_abs_2603_01264
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle S2O: Enhancing Adversarial Training with Second-Order Statistics of Weights
Jin, Gaojie
Yi, Xinping
Huang, Wei
Schewe, Sven
Huang, Xiaowei
Machine Learning
Adversarial training has emerged as a highly effective way to improve the robustness of deep neural networks (DNNs). It is typically conceptualized as a min-max optimization problem over model weights and adversarial perturbations, where the weights are optimized using gradient descent methods, such as SGD. In this paper, we propose a novel approach by treating model weights as random variables, which paves the way for enhancing adversarial training through \textbf{S}econd-Order \textbf{S}tatistics \textbf{O}ptimization (S$^2$O) over model weights. We challenge and relax a prevalent, yet often unrealistic, assumption in prior PAC-Bayesian frameworks: the statistical independence of weights. From this relaxation, we derive an improved PAC-Bayesian robust generalization bound. Our theoretical developments suggest that optimizing the second-order statistics of weights can substantially tighten this bound. We complement this theoretical insight by conducting an extensive set of experiments that demonstrate that S$^2$O not only enhances the robustness and generalization of neural networks when used in isolation, but also seamlessly augments other state-of-the-art adversarial training techniques. The code is available at https://github.com/Alexkael/S2O.
title S2O: Enhancing Adversarial Training with Second-Order Statistics of Weights
topic Machine Learning
url https://arxiv.org/abs/2603.01264