Best-of-Both Worlds for linear contextual bandits with paid observations

Fuente: arXiv
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Main Authors: Boyer, Nathan, Baudry, Dorian, Rebeschini, Patrick
Format: Preprint
Published: 2025
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author Boyer, Nathan
Baudry, Dorian
Rebeschini, Patrick
author_facet Boyer, Nathan
Baudry, Dorian
Rebeschini, Patrick
contents We study the problem of linear contextual bandits with paid observations, where at each round the learner selects an action in order to minimize its loss in a given context, and can then decide to pay a fixed cost to observe the loss of any arm. Building on the Follow-the-Regularized-Leader framework with efficient estimators via Matrix Geometric Resampling, we introduce a computationally efficient Best-of-Both-Worlds (BOBW) algorithm for this problem. We show that it achieves the minimax-optimal regret of $Θ(T^{2/3})$ in adversarial settings, while guaranteeing poly-logarithmic regret in (corrupted) stochastic regimes. Our approach builds on the framework from \cite{BOBWhardproblems} to design BOBW algorithms for ``hard problem'', using analysis techniques tailored for the setting that we consider.
format Preprint
id arxiv_https___arxiv_org_abs_2510_07424
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Best-of-Both Worlds for linear contextual bandits with paid observations
Boyer, Nathan
Baudry, Dorian
Rebeschini, Patrick
Machine Learning
We study the problem of linear contextual bandits with paid observations, where at each round the learner selects an action in order to minimize its loss in a given context, and can then decide to pay a fixed cost to observe the loss of any arm. Building on the Follow-the-Regularized-Leader framework with efficient estimators via Matrix Geometric Resampling, we introduce a computationally efficient Best-of-Both-Worlds (BOBW) algorithm for this problem. We show that it achieves the minimax-optimal regret of $Θ(T^{2/3})$ in adversarial settings, while guaranteeing poly-logarithmic regret in (corrupted) stochastic regimes. Our approach builds on the framework from \cite{BOBWhardproblems} to design BOBW algorithms for ``hard problem'', using analysis techniques tailored for the setting that we consider.
title Best-of-Both Worlds for linear contextual bandits with paid observations
topic Machine Learning
url https://arxiv.org/abs/2510.07424