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We study the best-arm identification (BAI) problem with a fixed budget and contextual (covariate) information. In each round of an adaptive experiment, after observing contextual information, we choose a treatment arm using past…

Machine Learning · Computer Science 2023-01-05 Masahiro Kato , Masaaki Imaizumi , Takuya Ishihara , Toru Kitagawa

We introduce Box Thirding (B3), a flexible and efficient algorithm for Best Arm Identification (BAI) under fixed-budget constraints. It is designed for both anytime BAI and scenarios with large N, where the number of arms is too large for…

Machine Learning · Statistics 2026-02-23 Seohwa Hwang , Junyong Park

We study the problem of best-arm identification with fixed confidence in stochastic linear bandits. The objective is to identify the best arm with a given level of certainty while minimizing the sampling budget. We devise a simple algorithm…

Machine Learning · Statistics 2020-06-30 Yassir Jedra , Alexandre Proutiere

Best arm identification (BAI) aims to identify the highest-performance arm among a set of $K$ arms by collecting stochastic samples from each arm. In real-world problems, the best arm needs to satisfy additional feasibility constraints.…

Machine Learning · Computer Science 2026-01-26 Ting Cai , Kirthevasan Kandasamy

Fixed-budget best-arm identification (BAI) is a bandit problem where the agent maximizes the probability of identifying the optimal arm within a fixed budget of observations. In this work, we study this problem in the Bayesian setting. We…

Machine Learning · Computer Science 2023-06-16 Alexia Atsidakou , Sumeet Katariya , Sujay Sanghavi , Branislav Kveton

Motivated by real-world applications that necessitate responsible experimentation, we introduce the problem of best arm identification (BAI) with minimal regret. This innovative variant of the multi-armed bandit problem elegantly…

Machine Learning · Computer Science 2024-09-30 Junwen Yang , Vincent Y. F. Tan , Tianyuan Jin

This paper considers the optimal adaptive allocation of measurement effort for identifying the best among a finite set of options or designs. An experimenter sequentially chooses designs to measure and observes noisy signals of their…

Machine Learning · Computer Science 2018-06-11 Daniel Russo

We consider the problem of finding, through adaptive sampling, which of $n$ options (arms) has the largest mean. Our objective is to determine a rule which identifies the best arm with a fixed minimum confidence using as few observations as…

Machine Learning · Computer Science 2022-03-17 MohammadJavad Azizi , Sheldon M Ross , Zhengyu Zhang

We consider the best-arm identification problem in multi-armed bandits, which focuses purely on exploration. A player is given a fixed budget to explore a finite set of arms, and the rewards of each arm are drawn independently from a fixed,…

Machine Learning · Statistics 2017-08-02 Shahin Shahrampour , Mohammad Noshad , Vahid Tarokh

This study investigates an asymptotically locally minimax optimal algorithm for fixed-budget best-arm identification (BAI). We propose the Generalized Neyman Allocation (GNA) algorithm and demonstrate that its worst-case upper bound on the…

Machine Learning · Computer Science 2025-02-04 Masahiro Kato

This paper investigates the problem of best arm identification in $\textit{contaminated}$ stochastic multi-arm bandits. In this setting, the rewards obtained from any arm are replaced by samples from an adversarial model with probability…

Machine Learning · Computer Science 2021-11-16 Arpan Mukherjee , Ali Tajer , Pin-Yu Chen , Payel Das

We consider a best arm identification (BAI) problem for stochastic bandits with adversarial corruptions in the fixed-budget setting of T steps. We design a novel randomized algorithm, Probabilistic Sequential Shrinking($u$) (PSS($u$)),…

Machine Learning · Computer Science 2021-06-21 Zixin Zhong , Wang Chi Cheung , Vincent Y. F. Tan

Motivated by wireless networks where interference or channel state estimates provide partial insight into throughput, we study a variant of the classical stochastic multi-armed bandit problem in which the learner has limited access to…

Machine Learning · Computer Science 2026-03-03 Arun Verma , Manjesh Kumar Hanawal , Arun Rajkumar

We study the nonstationary stochastic Multi-Armed Bandit (MAB) problem in which the distribution of rewards associated with each arm are assumed to be time-varying and the total variation in the expected rewards is subject to a variation…

Machine Learning · Computer Science 2021-01-25 Lai Wei , Vaibhav Srivastava

One of the key drivers of complexity in the classical (stochastic) multi-armed bandit (MAB) problem is the difference between mean rewards in the top two arms, also known as the instance gap. The celebrated Upper Confidence Bound (UCB)…

Machine Learning · Computer Science 2021-10-27 Anand Kalvit , Assaf Zeevi

We study the problem of identifying the best arm in a multi-armed bandit environment when each arm is a time-homogeneous and ergodic discrete-time Markov process on a common, finite state space. The state evolution on each arm is governed…

Machine Learning · Statistics 2022-03-30 P. N. Karthik , Kota Srinivas Reddy , Vincent Y. F. Tan

We propose EB-TC$\varepsilon$, a novel sampling rule for $\varepsilon$-best arm identification in stochastic bandits. It is the first instance of Top Two algorithm analyzed for approximate best arm identification. EB-TC$\varepsilon$ is an…

Machine Learning · Statistics 2023-11-07 Marc Jourdan , Rémy Degenne , Emilie Kaufmann

We study the fixed-confidence best-arm identification problem in unimodal bandits, in which the means of the arms increase with the index of the arm up to their maximum, then decrease. We derive two lower bounds on the stopping time of any…

Machine Learning · Computer Science 2025-05-27 Riccardo Poiani , Marc Jourdan , Emilie Kaufmann , Rémy Degenne

The challenge of identifying the best feasible arm within a fixed budget has attracted considerable interest in recent years. However, a notable gap remains in the literature: the exact exponential rate at which the error probability…

Machine Learning · Computer Science 2025-06-04 Jie Bian , Vincent Y. F. Tan

Given a finite set of unknown distributions or arms that can be sampled, we consider the problem of identifying the one with the maximum mean using a $\delta$-correct algorithm (an adaptive, sequential algorithm that restricts the…

Machine Learning · Computer Science 2023-11-27 Shubhada Agrawal , Sandeep Juneja , Peter Glynn