Adversary-Robust Learning from Fully Asynchronous Directional Derivative Estimates

Fuente: arXiv
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Autori principali: Paul, Anik Kumar, Roy, Nibedita, Talagani, Nagesh, Ganesh, Swetha, Thoppe, Gugan, Reiffers-Masson, Alexandre
Natura: Preprint
Pubblicazione: 2026
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author Paul, Anik Kumar
Roy, Nibedita
Talagani, Nagesh
Ganesh, Swetha
Thoppe, Gugan
Reiffers-Masson, Alexandre
author_facet Paul, Anik Kumar
Roy, Nibedita
Talagani, Nagesh
Ganesh, Swetha
Thoppe, Gugan
Reiffers-Masson, Alexandre
contents We propose FAR-SIGN (Fully Asynchronous Robust optimization via SIGNed directional projections) for adversary-resilient learning in parameter-server--worker systems. FAR-SIGN achieves robustness through sign-based updates along carefully designed directions and mitigates the resulting bias via a two-timescale mechanism. It admits both first-order and zeroth-order implementations and enables fully asynchronous execution without requiring a private reference dataset at the server. We establish almost-sure convergence of FAR-SIGN to the set of stationary points for smooth, nonconvex objectives. Moreover, we prove the near-optimal rate of $O(n^{-1/4+ε})$ in the first-order setting and the standard $O(n^{-1/6+ε})$ in the zeroth-order setting, where $n$ is the iteration count and $ε>0$ can be chosen arbitrarily small. Experiments on MNIST show that FAR-SIGN outperforms robust aggregation-based methods in both accuracy and wall-clock time.
format Preprint
id arxiv_https___arxiv_org_abs_2605_09337
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Adversary-Robust Learning from Fully Asynchronous Directional Derivative Estimates
Paul, Anik Kumar
Roy, Nibedita
Talagani, Nagesh
Ganesh, Swetha
Thoppe, Gugan
Reiffers-Masson, Alexandre
Machine Learning
Optimization and Control
We propose FAR-SIGN (Fully Asynchronous Robust optimization via SIGNed directional projections) for adversary-resilient learning in parameter-server--worker systems. FAR-SIGN achieves robustness through sign-based updates along carefully designed directions and mitigates the resulting bias via a two-timescale mechanism. It admits both first-order and zeroth-order implementations and enables fully asynchronous execution without requiring a private reference dataset at the server. We establish almost-sure convergence of FAR-SIGN to the set of stationary points for smooth, nonconvex objectives. Moreover, we prove the near-optimal rate of $O(n^{-1/4+ε})$ in the first-order setting and the standard $O(n^{-1/6+ε})$ in the zeroth-order setting, where $n$ is the iteration count and $ε>0$ can be chosen arbitrarily small. Experiments on MNIST show that FAR-SIGN outperforms robust aggregation-based methods in both accuracy and wall-clock time.
title Adversary-Robust Learning from Fully Asynchronous Directional Derivative Estimates
topic Machine Learning
Optimization and Control
url https://arxiv.org/abs/2605.09337