Sharp analysis of linear ensemble sampling

Fuente: arXiv
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Main Authors: Akhavan, Arya, Janz, David, Szepesvári, Csaba
Format: Preprint
Published: 2026
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author Akhavan, Arya
Janz, David
Szepesvári, Csaba
author_facet Akhavan, Arya
Janz, David
Szepesvári, Csaba
contents We analyse linear ensemble sampling (ES) with standard Gaussian perturbations in stochastic linear bandits. We show that for ensemble size $m=Θ(d\log n)$, ES attains $\tilde O(d^{3/2}\sqrt n)$ high-probability regret, closing the gap to the Thompson sampling benchmark while keeping computation comparable. The proof brings a new perspective on randomized exploration in linear bandits by reducing the analysis to a time-uniform exceedance problem for $m$ independent Brownian motions. Intriguingly, this continuous-time lens is not forced; it appears natural--and perhaps necessary: the discrete-time problem seems to be asking for a continuous-time solution, and we know of no other way to obtain a sharp ES bound.
format Preprint
id arxiv_https___arxiv_org_abs_2602_08026
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Sharp analysis of linear ensemble sampling
Akhavan, Arya
Janz, David
Szepesvári, Csaba
Machine Learning
We analyse linear ensemble sampling (ES) with standard Gaussian perturbations in stochastic linear bandits. We show that for ensemble size $m=Θ(d\log n)$, ES attains $\tilde O(d^{3/2}\sqrt n)$ high-probability regret, closing the gap to the Thompson sampling benchmark while keeping computation comparable. The proof brings a new perspective on randomized exploration in linear bandits by reducing the analysis to a time-uniform exceedance problem for $m$ independent Brownian motions. Intriguingly, this continuous-time lens is not forced; it appears natural--and perhaps necessary: the discrete-time problem seems to be asking for a continuous-time solution, and we know of no other way to obtain a sharp ES bound.
title Sharp analysis of linear ensemble sampling
topic Machine Learning
url https://arxiv.org/abs/2602.08026