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In fixed budget bandit identification, an algorithm sequentially observes samples from several distributions up to a given final time. It then answers a query about the set of distributions. A good algorithm will have a small probability of…

Machine Learning · Statistics 2023-07-03 Rémy Degenne

We consider a variant of the best arm identification (BAI) problem in multi-armed bandits (MAB) in which there are two sets of arms (source and target), and the objective is to determine the best target arm while only pulling source arms.…

Machine Learning · Computer Science 2021-12-09 Ojash Neopane , Aaditya Ramdas , Aarti Singh

In the Best-$K$ identification problem (Best-$K$-Arm), we are given $N$ stochastic bandit arms with unknown reward distributions. Our goal is to identify the $K$ arms with the largest means with high confidence, by drawing samples from the…

Machine Learning · Computer Science 2017-05-22 Haotian Jiang , Jian Li , Mingda Qiao

We consider fixed-budget best-arm identification in two-armed Gaussian bandit problems. One of the longstanding open questions is the existence of an optimal strategy under which the probability of misidentification matches a lower bound.…

Machine Learning · Statistics 2023-01-02 Masahiro Kato , Kaito Ariu , Masaaki Imaizumi , Masahiro Nomura , Chao Qin

The improving multi-armed bandits problem is a formal model for allocating effort under uncertainty, motivated by scenarios such as investing research effort into new technologies, performing clinical trials, and hyperparameter selection…

Machine Learning · Computer Science 2026-05-22 Avrim Blum , Marten Garicano , Kavya Ravichandran , Dravyansh Sharma

This study investigates an asymptotically minimax optimal algorithm in the two-armed fixed-budget best-arm identification (BAI) problem. Given two treatment arms, the objective is to identify the arm with the highest expected outcome…

Machine Learning · Statistics 2025-01-23 Masahiro Kato

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 give a complete characterization of the complexity of best-arm identification in one-parameter bandit problems. We prove a new, tight lower bound on the sample complexity. We propose the `Track-and-Stop' strategy, which we prove to be…

Statistics Theory · Mathematics 2016-06-02 Aurélien Garivier , Emilie Kaufmann

We consider the best arm identification problem, where the goal is to identify the arm with the highest mean reward from a set of $K$ arms under a limited sampling budget. This problem models many practical scenarios such as A/B testing. We…

Machine Learning · Statistics 2026-05-05 Junpei Komiyama , Kyoungseok Jang , Junya Honda

This paper focuses on selecting the arm with the highest variance from a set of $K$ independent arms. Specifically, we focus on two settings: (i) misallocation minimization setting, that penalizes the number of pulls of suboptimal arms in…

Machine Learning · Computer Science 2026-02-18 Sabrina Khurshid , Gourab Ghatak , Mohammad Shahid Abdulla

Many real-world functions are defined over both categorical and category-specific continuous variables and thus cannot be optimized by traditional Bayesian optimization (BO) methods. To optimize such functions, we propose a new method that…

Machine Learning · Computer Science 2019-12-02 Dang Nguyen , Sunil Gupta , Santu Rana , Alistair Shilton , Svetha Venkatesh

We consider the problem of identifying the best arm in a multi-armed bandit model. Despite a wealth of literature in the traditional fixed budget and fixed confidence regimes of the best arm identification problem, it still remains a…

Machine Learning · Statistics 2025-12-08 Michael O. Harding , Kirthevasan Kandasamy

We study the problem of best arm identification in linearly parameterised multi-armed bandits. Given a set of feature vectors $\mathcal{X}\subset\mathbb{R}^d,$ a confidence parameter $\delta$ and an unknown vector $\theta^*,$ the goal is to…

Machine Learning · Computer Science 2020-06-16 Mohammadi Zaki , Avi Mohan , Aditya Gopalan

We study the fixed-confidence best arm identification (BAI) problem within the multi-armed bandit (MAB) framework under the Entropic Value-at-Risk (EVaR) criterion. Our analysis considers a nonparametric setting, allowing for general reward…

Machine Learning · Computer Science 2025-10-07 Mehrasa Ahmadipour , Aurélien Garivier

We investigate the problem of fixed-budget best arm identification (BAI) for minimizing expected simple regret. In an adaptive experiment, a decision maker draws one of multiple treatment arms based on past observations and observes the…

Machine Learning · Computer Science 2023-07-13 Masahiro Kato , Masaaki Imaizumi , Takuya Ishihara , Toru Kitagawa

We consider the problem of the best arm identification in the presence of stochastic constraints, where there is a finite number of arms associated with multiple performance measures. The goal is to identify the arm that optimizes the…

Machine Learning · Computer Science 2025-01-08 Le Yang , Siyang Gao , Cheng Li , Yi Wang

The 1-identification problem is a fundamental pure-exploration problem in multi-armed bandits. An agent aims to determine whether there exists an arm whose mean reward exceeds a known threshold $\mu_0$, or to output \textsf{None} otherwise.…

Machine Learning · Computer Science 2026-05-15 Zitian Li , Wang Chi Cheung

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

Stochastic Rising Bandits (SRBs) model sequential decision-making problems in which the expected reward of the available options increases every time they are selected. This setting captures a wide range of scenarios in which the available…

Machine Learning · Computer Science 2024-05-29 Marco Mussi , Alessandro Montenegro , Francesco Trovó , Marcello Restelli , Alberto Maria Metelli

We consider the problem of best arm identification in a variant of multi-armed bandits called linked bandits. In a single interaction with linked bandits, multiple arms are played sequentially until one of them receives a positive reward.…

Machine Learning · Computer Science 2019-01-29 Anant Gupta