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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

We consider the problem of best arm identification in the multi-armed bandit model, under fixed confidence. Given a confidence input $\delta$, the goal is to identify the arm with the highest mean reward with a probability of at least 1 --…

Machine Learning · Statistics 2023-12-21 El Mehdi Saad , Gilles Blanchard , Nicolas Verzelen

Traditional multi-armed bandit (MAB) formulations usually make certain assumptions about the underlying arms' distributions, such as bounds on the support or their tail behaviour. Moreover, such parametric information is usually 'baked'…

Machine Learning · Computer Science 2022-03-29 Anmol Kagrecha , Jayakrishnan Nair , Krishna Jagannathan

In this paper, we study the behavior of the Upper Confidence Bound-Variance (UCB-V) algorithm for the Multi-Armed Bandit (MAB) problems, a variant of the canonical Upper Confidence Bound (UCB) algorithm that incorporates variance estimates…

Machine Learning · Statistics 2025-02-18 Yingying Fan , Yuxuan Han , Jinchi Lv , Xiaocong Xu , Zhengyuan Zhou

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 paper proposes a novel upper confidence bound (UCB) procedure for identifying the arm with the largest mean in a multi-armed bandit game in the fixed confidence setting using a small number of total samples. The procedure cannot be…

Machine Learning · Statistics 2013-12-30 Kevin Jamieson , Matthew Malloy , Robert Nowak , Sébastien Bubeck

We present a provably optimal differentially private algorithm for the stochastic multi-arm bandit problem, as opposed to the private analogue of the UCB-algorithm [Mishra and Thakurta, 2015; Tossou and Dimitrakakis, 2016] which doesn't…

Machine Learning · Statistics 2019-05-24 Touqir Sajed , Or Sheffet

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 consider a variant of the best arm identification task in stochastic multi-armed bandits. Motivated by risk-averse decision-making problems, our goal is to identify a set of $m$ arms with the highest $\tau$-quantile values within a fixed…

Machine Learning · Computer Science 2023-02-22 Mengyan Zhang , Cheng Soon Ong

Top-$2$ methods have become popular in solving the best arm identification (BAI) problem. The best arm, or the arm with the largest mean amongst finitely many, is identified through an algorithm that at any sequential step independently…

Machine Learning · Computer Science 2024-12-17 Agniv Bandyopadhyay , Sandeep Juneja , Shubhada Agrawal

In bandit best-arm identification, an algorithm is tasked with finding the arm with highest mean reward with a specified accuracy as fast as possible. We study multi-fidelity best-arm identification, in which the algorithm can choose to…

Machine Learning · Computer Science 2025-05-27 Riccardo Poiani , Rémy Degenne , Emilie Kaufmann , Alberto Maria Metelli , Marcello Restelli

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

In many applications, evaluating the effectiveness of different alternatives comes with varying costs or resource usage. Motivated by such heterogeneity, we study the Best Arm Identification with Resource Constraints (BAIwRC) problem, where…

Machine Learning · Computer Science 2026-03-02 Zitian Li , Wang Chi Cheung

In this paper, we introduce the constrained best mixed arm identification (CBMAI) problem with a fixed budget. This is a pure exploration problem in a stochastic finite armed bandit model. Each arm is associated with a reward and multiple…

Machine Learning · Computer Science 2024-05-27 Dengwang Tang , Rahul Jain , Ashutosh Nayyar , Pierluigi Nuzzo

We study best arm identification (BAI) in linear bandits in the fixed-budget regime under differential privacy constraints, when the arm rewards are supported on the unit interval. Given a finite budget $T$ and a privacy parameter…

Machine Learning · Computer Science 2024-01-18 Zhirui Chen , P. N. Karthik , Yeow Meng Chee , Vincent Y. F. Tan

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 study the fixed-budget best-arm identification (BAI) problem in non-stationary linear bandits. Concretely, given a fixed time budget $T\in \mathbb{N}$, finite arm set $\mathcal{X} \subset \mathbb{R}^d$, and a potentially adversarial…

Machine Learning · Statistics 2026-03-12 Leo Maynard-Zhang , Zhihan Xiong , Kevin Jamieson , Maryam Fazel

This paper investigates a hitherto unaddressed aspect of best arm identification (BAI) in stochastic multi-armed bandits in the fixed-confidence setting. Two key metrics for assessing bandit algorithms are computational efficiency and…

Machine Learning · Statistics 2023-06-26 Arpan Mukherjee , Ali Tajer

We consider a good arm identification problem in a stochastic bandit setting with multi-objectives, where each arm $i \in [K]$ is associated with a distribution $D_i$ defined over $R^M$. For each round $t$, the player pulls an arm $i_t$ and…

Machine Learning · Computer Science 2025-06-30 Xuanke Jiang , Sherief Hashima , Kohei Hatano , Eiji Takimoto

This study investigates minimax and Bayes optimal strategies for fixed-budget best-arm identification. We consider an adaptive procedure consisting of a sampling phase followed by a recommendation phase, and we design an adaptive experiment…

Econometrics · Economics 2026-02-05 Masahiro Kato