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In this paper, we discuss the asymptotic behavior of the Upper Confidence Bound (UCB) algorithm in the context of multiarmed bandit problems and discuss its implication in downstream inferential tasks. While inferential tasks become…

Machine Learning · Statistics 2024-08-09 Koulik Khamaru , Cun-Hui Zhang

We propose the first fully-adaptive algorithm for pure exploration in linear bandits---the task to find the arm with the largest expected reward, which depends on an unknown parameter linearly. While existing methods partially or entirely…

Machine Learning · Statistics 2017-10-17 Liyuan Xu , Junya Honda , Masashi Sugiyama

We lay the foundations of a non-parametric theory of best-arm identification in multi-armed bandits with a fixed budget T. We consider general, possibly non-parametric, models D for distributions over the arms; an overarching example is the…

Machine Learning · Computer Science 2023-02-07 Antoine Barrier , Aurélien Garivier , Gilles Stoltz

We study best arm identification in a federated multi-armed bandit setting with a central server and multiple clients, when each client has access to a {\em subset} of arms and each arm yields independent Gaussian observations. The goal is…

Machine Learning · Computer Science 2023-12-20 Zhirui Chen , P. N. Karthik , Vincent Y. F. Tan , Yeow Meng Chee

Decision making under uncertain environments in the maximization of expected reward while minimizing its risk is one of the ubiquitous problems in many subjects. Here, we introduce a novel problem setting in stochastic bandit optimization…

Machine Learning · Computer Science 2025-10-27 Shunta Nonaga , Koji Tabata , Yuta Mizuno , Tamiki Komatsuzaki

The best arm identification problem requires identifying the best alternative (i.e., arm) in active experimentation using the smallest number of experiments (i.e., arm pulls), which is crucial for cost-efficient and timely decision-making…

Machine Learning · Computer Science 2025-06-17 Kapilan Balagopalan , Tuan Ngo Nguyen , Yao Zhao , Kwang-Sung Jun

We study best-arm identification in stochastic dueling bandits under the sole assumption that a Condorcet winner exists, i.e., an arm that wins each noisy pairwise comparison with probability at least $1/2$. We introduce a new…

Machine Learning · Statistics 2026-03-17 El Mehdi Saad , Victor Thuot , Nicolas Verzelen

We study best arm identification in a restless multi-armed bandit setting with finitely many arms. The discrete-time data generated by each arm forms a homogeneous Markov chain taking values in a common, finite state space. The state…

Machine Learning · Statistics 2024-06-25 P. N. Karthik , Vincent Y. F. Tan , Arpan Mukherjee , Ali Tajer

Motivated by an open direction in existing literature, we study the 1-identification problem, a fundamental multi-armed bandit formulation on pure exploration. The goal is to determine whether there exists an arm whose mean reward is at…

Machine Learning · Computer Science 2025-08-21 Zitian Li , Wang Chi Cheung

The classic multi-armed bandit (MAB) problem tackles the challenge of accruing maximum reward while making decisions under uncertainty. However, in applications, often the goal is to minimize cost subject to a constraint on the minimum…

Machine Learning · Computer Science 2026-05-11 Ishank Juneja , Carlee Joe-Wong , Osman Yağan

We investigate Learning from Label Proportions (LLP), a partial information setting where examples in a training set are grouped into bags, and only aggregate label values in each bag are available. Despite the partial observability, the…

Machine Learning · Computer Science 2025-06-02 Robert Busa-Fekete , Travis Dick , Claudio Gentile , Haim Kaplan , Tomer Koren , Uri Stemmer

In this paper, we study the stochastic multi-armed bandit problem, where the reward is driven by an unknown random variable. We propose a new variant of the Upper Confidence Bound (UCB) algorithm called Hellinger-UCB, which leverages the…

Machine Learning · Statistics 2024-04-17 Ruibo Yang , Jiazhou Wang , Andrew Mullhaupt

Thompson sampling has become a ubiquitous approach to online decision problems with bandit feedback. The key algorithmic task for Thompson sampling is drawing a sample from the posterior of the optimal action. We propose an alternative arm…

Machine Learning · Computer Science 2021-05-05 Jackie Baek , Vivek F. Farias

This paper formulates a new Best-Arm Identification problem in the non-stationary stochastic bandits setting, where the means of all arms are shifted in the same way due to a global influence of the environment. The aim is to identify the…

Machine Learning · Computer Science 2024-08-23 Phurinut Srisawad , Juergen Branke , Long Tran-Thanh

Selecting the best alternative from a finite set represents a broad class of pure exploration problems. Traditional approaches to pure exploration have predominantly relied on Gaussian or sub-Gaussian assumptions on the performance…

Machine Learning · Statistics 2025-12-01 Zaile Li , Weiwei Fan , L. Jeff Hong

This work formulates model selection as an infinite-armed bandit problem, namely, a problem in which a decision maker iteratively selects one of an infinite number of fixed choices (i.e., arms) when the properties of each choice are only…

Neural and Evolutionary Computing · Computer Science 2024-06-21 Margaux Brégère , Julie Keisler

Combinatorial linear semi-bandits (CLS) are widely applicable frameworks of sequential decision-making, in which a learner chooses a subset of arms from a given set of arms associated with feature vectors. Existing algorithms work poorly…

Machine Learning · Statistics 2019-09-11 Kei Takemura , Shinji Ito

We study the problem of the identification of m arms with largest means under a fixed error rate $\delta$ (fixed-confidence Top-m identification), for misspecified linear bandit models. This problem is motivated by practical applications,…

Artificial Intelligence · Computer Science 2021-11-03 Clémence Réda , Andrea Tirinzoni , Rémy Degenne

We study the problem of best-arm identification with fixed budget in stochastic multi-armed bandits with Bernoulli rewards. For the problem with two arms, also known as the A/B testing problem, we prove that there is no algorithm that (i)…

Machine Learning · Statistics 2024-06-05 Po-An Wang , Kaito Ariu , Alexandre Proutiere

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