arXiv Machine Learning

Adversarial Training with Large Step Sizes: Implicit Bias, Optimization, and Sharpness

The paper investigates how deterministic Gradient Descent behaves when applied to Adversarial Training with large, constant step sizes. It analyzes both a linear logistic regression setting—examining where parameters converge (implicit bias) and how fast losses decrease (optimization)—and neural network training, focusing on the evolution of loss sharpness. The study reveals three key distinctions from Standard Training: the implicit bias gap persists even with large steps, there is no uniform convergence rate for optimization error, and sharpness follows a two‑stage dynamic unlike the Edge‑of‑Stability pattern seen in Standard Training.

arXiv AI
Oct 12

On the Rate of Convergence of GD in Non-linear Neural Networks: An Adversarial Robustness Perspective

The paper analyzes Gradient Descent (GD) on a minimal binary classification problem with a two‑neuron ReLU network trained on two instances. It proves that GD converges to an optimal robustness margin—maximizing the distance between the decision boundary and training points—but does so at a very slow rate, specifically θ(1/ln(t)). Empirical simulations confirm this slow convergence across various initializations, and the authors provide a rigorous analysis of GD trajectories across different activation patterns to establish the first explicit lower bound on robustness convergence in a non‑linear model.

By Guy Smorodinsky, Sveta Gimpleson, Itay Safran
arXiv AI
Oct 26

Catastrophic Overfitting, Entropy Gap and Participation Ratio: A Noiseless $l^p$ Norm Solution for Fast Adversarial Training

arXiv:2505. 02360v3 Announce Type: replace-cross Abstract: Adversarial training is a cornerstone of robust deep learning, but fast methods like the Fast Gradient Sign Method (FGSM) often suffer from Catastrophic Overfitting (CO), where models become robust to single-step attacks but fail against multi-step variants.

By Fares B. Mehouachi, Saif Eddin Jabari
arXiv AI
Jun 2

SORA: Free Second-Order Attacks in Fast Adversarial Training

arXiv:2606. 00738v1 Announce Type: cross Abstract: Adversarial Training (AT) is a leading defense against adversarial examples but often suffers from Catastrophic Overfitting (CO) in efficient single-step variants, where robustness to multi-step attacks collapses despite high single-step performance.

By Mazdak Teymourian, Ramtin Moslemi, Farzan Rahmani, Mohammad Hossein Rohban
arXiv AI
Sep 21

Taming the Adversary: A Cost-to-Disturbance Ratio Approach to Adversarial Reinforcement Learning

The paper introduces CoDRA, a cost-to-disturbance ratio approach for adversarial reinforcement learning that balances controller performance and disturbance exposure without extra penalty terms. CoDRA uses a self‑normalized actor–critic update, scaling value terms by a stop‑gradient normalization constant derived from the current batch. Experiments on MuJoCo pendulum tasks show that CoDRA achieves the lowest cost across a range of forces and masses, outperforming other methods especially on the more challenging InvertedDoublePendulum environment.

By Taeho Lee, Donghwan Lee
arXiv Machine Learning
Oct 12

Controlled-Minimax: Stabilizing Adversarial Optimization via Control Theory

Controlled-Minimax is a new framework that stabilizes adversarial minimax optimization by modeling training dynamics as a second-order ODE and applying a feedback controller derived from control theory. The method guarantees local exponential stability regardless of the Hessian spectrum, addressing persistent limit cycles and divergence that plague traditional gradient descent-ascent approaches. Experiments on benchmarks such as Dirac-GAN, 2D Gaussian mixtures, Swiss Roll, and StyleGAN2-ada show that Controlled-Minimax suppresses oscillations and achieves fast, robust convergence.

By Tianjiao Luo, Jianfei Chen, Jun Zhu
arXiv Machine Learning
Oct 9

Grokking or Glitching? How Low-Precision Drives Slingshot Loss Spikes

Deep neural networks can exhibit periodic loss spikes known as the "Slingshot Mechanism" during long‑term training. This paper shows that such spikes arise from finite‑precision floating‑point arithmetic: when the correct‑class logit becomes much larger than the others, the gradient for that class is rounded to zero while others remain nonzero, breaking the zero‑sum constraint and creating a positive feedback loop that inflates feature and classifier norms. The authors term this Numerical Feature Inflation (NFI) and demonstrate that it explains the rapid norm growth, reappearance of gradients, and loss spikes, while also showing that partial absorption can still cause hidden norm growth without visible spikes.

By Hanqing Liu, Jianjun Cao, Yuanze Li, Zijian Zhou