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Homogenization of $\ell_2$-Adversarial Training in High-Dimensions: Exact Dynamics under Stochastic Gradient Descent

arXiv.org Machine Learning

We develop a framework for analyzing the learning dynamics of $\ell_2$-adversarial training of single-index models on Gaussian mixtures in the high-dimensional limit under streaming stochastic gradient descent (SGD). We derive deterministic equivalents for a broad class of statistics of the SGD iterates, including the adversarial risk and distance to adversarial optimality, in terms of the solution to a system of ODEs. We use them to study two idealized learning rate schedules: the Polyak stepsize and exact line search. In the case of $\ell_2$-adversarial least squares with a single class, we show that, unlike noiseless standard least squares, no constant learning rate guarantees monotone descent of SGD towards a minimizer of the adversarial risk. We identify anisotropic covariance and a mismatch in ridge parameters as the main sources of suboptimality of exact line search relative to the Polyak stepsize. We also introduce a stochastic differential equation (SDE), called adversarial homogenized SGD, that captures the evolution of statistics of the iterates of SGD. For $\ell_2$-adversarial least squares, using this SDE, we show the evolution of the risk is equivalent, up to dimension-free constants, to that of SGD on standard least squares with an adaptive learning rate and adaptive $\ell_2$-regularization. When the dynamics converge, the limiting adversarial risk and SGD iterate are determined by a fixed-point equation, with the limiting iterate being equivalent to the solution of a ridge regression problem whose regularization parameter is the limiting effective regularization of SGD.


Deep Autocorrelation Modeling for Time-Series Forecasting: Progress and Prospects

arXiv.org Machine Learning

Autocorrelation is a defining characteristic of time-series data, where each observation is statistically dependent on its predecessors. In the context of deep time-series forecasting, autocorrelation arises in both the input history and the label sequences, presenting two central research challenges: (1) designing neural architectures that model autocorrelation in history sequences, and (2) devising learning objectives that model autocorrelation in label sequences. Recent studies have made strides in tackling these challenges, but a systematic survey examining both aspects remains lacking. To bridge this gap, this paper provides a comprehensive review of deep time-series forecasting from the perspective of autocorrelation modeling. In contrast to existing surveys, this work makes two distinctive contributions. First, it proposes a novel taxonomy that encompasses recent literature on both model architectures and learning objectives -- whereas prior surveys neglect or inadequately discuss the latter aspect. Second, it offers a thorough analysis of the motivations, insights, and progression of the surveyed literature from a unified, autocorrelation-centric perspective, providing a holistic overview of the evolution of deep time-series forecasting. The full list of papers and resources is available at https://github.com/Master-PLC/Awesome-TSF-Papers.


DataStealing

Neural Information Processing Systems

Federated Learning (FL) iscommonly used tocollaborativelytrain models with privacypreservation. Specifically,AdaSCP evaluates the importance of parameters with the gradients in dominant timesteps of the diffusion model.



A Appendix

Neural Information Processing Systems

A.1 TPPE Method We present the pseudo code for TPPE in this paper, using the Insertion mode as an example. According to Alg. 1, we reduce the query time complexity from In our study, we assume the worst-case scenario of applying punctuation-level attacks. Softmax layer is adopted to predict the label of the input text. Paraphrase (TPPEP) to achieve a single-shot attack. We describe the TPPEP method as being decomposed into two parts: training and searching.




An adaptive nearest neighbor rule for classification

Neural Information Processing Systems

Findthesmallest0 (n, k, ), where (n, k, )= c1 r logn+ log ( 1/ ) k . Then, withprobabilityatleast1 , theresultingclassifiergn satisfiesthefollowing: foreverypointx 2 supp(ยต), if n C adv (x) max log 1 adv (x) , log 1 thengn(x)= g (x).