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In this work, we present a novel framework for Best Arm Identification (BAI) under fairness constraints, a setting that we refer to as \textit{F-BAI} (fair BAI). Unlike traditional BAI, which solely focuses on identifying the optimal arm…

Machine Learning · Computer Science 2024-09-02 Alessio Russo , Filippo Vannella

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

We consider a novel stochastic multi-armed bandit problem called {\em good arm identification} (GAI), where a good arm is defined as an arm with expected reward greater than or equal to a given threshold. GAI is a pure-exploration problem…

We consider the problem of identifying the best arm in stochastic Multi-Armed Bandits (MABs) using a fixed sampling budget. Characterizing the minimal instance-specific error probability for this problem constitutes one of the important…

Machine Learning · Computer Science 2024-02-21 Po-An Wang , Ruo-Chun Tzeng , Alexandre Proutiere

We study the batched best arm identification (BBAI) problem, where the learner's goal is to identify the best arm while switching the policy as less as possible. In particular, we aim to find the best arm with probability $1-\delta$ for…

Machine Learning · Computer Science 2025-03-05 Tianyuan Jin , Yu Yang , Jing Tang , Xiaokui Xiao , Pan Xu

The multi-armed bandit (MAB) problem is a foundational framework in sequential decision-making under uncertainty, extensively studied for its applications in areas such as clinical trials, online advertising, and resource allocation.…

Machine Learning · Computer Science 2024-10-28 Ali Baheri

This work investigates the problem of best arm identification for multi-agent multi-armed bandits. We consider $N$ agents grouped into $M$ clusters, where each cluster solves a stochastic bandit problem. The mapping between agents and…

Machine Learning · Computer Science 2025-05-16 Yash , Nikhil Karamchandani , Avishek Ghosh

Offline (or batch) reinforcement learning (RL) algorithms seek to learn an optimal policy from a fixed dataset without active data collection. Based on the composition of the offline dataset, two main categories of methods are used:…

Machine Learning · Computer Science 2023-07-04 Paria Rashidinejad , Banghua Zhu , Cong Ma , Jiantao Jiao , Stuart Russell

We study best arm identification in a variant of the multi-armed bandit problem where the learner has limited precision in arm selection. The learner can only sample arms via certain exploration bundles, which we refer to as boxes. In…

Machine Learning · Computer Science 2023-05-11 Kota Srinivas Reddy , P. N. Karthik , Nikhil Karamchandani , Jayakrishnan Nair

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 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 online learning models are typically initialized from scratch. By contrast, contemporary real-world applications often have access to historical datasets that can potentially enhanced the online learning processes. We study how…

Machine Learning · Computer Science 2025-12-19 Wang Chi Cheung , Lixing Lyu

Recently multi-armed bandit problem arises in many real-life scenarios where arms must be sampled in batches, due to limited time the agent can wait for the feedback. Such applications include biological experimentation and online…

Machine Learning · Statistics 2023-12-22 Shengyu Cao , Simai He , Ruoqing Jiang , Jin Xu , Hongsong Yuan

We design and analyze CascadeBAI, an algorithm for finding the best set of $K$ items, also called an arm, within the framework of cascading bandits. An upper bound on the time complexity of CascadeBAI is derived by overcoming a crucial…

Machine Learning · Computer Science 2020-06-16 Zixin Zhong , Wang Chi Cheung , Vincent Y. F. Tan

We consider the best arm identification problem in the stochastic multi-armed bandit framework where each arm has a tiny probability of realizing large rewards while with overwhelming probability the reward is zero. A key application of…

Machine Learning · Computer Science 2023-03-15 Anirban Bhattacharjee , Sushant Vijayan , Sandeep K Juneja

We propose a {\em novel} piecewise stationary linear bandit (PSLB) model, where the environment randomly samples a context from an unknown probability distribution at each changepoint, and the quality of an arm is measured by its return…

Machine Learning · Computer Science 2024-10-11 Yunlong Hou , Vincent Y. F. Tan , Zixin Zhong

The regret lower bound of Lai and Robbins (1985), the gold standard for checking optimality of bandit algorithms, considers arm size fixed as sample size goes to infinity. We show that when arm size increases polynomially with sample size,…

Statistics Theory · Mathematics 2019-09-06 Hock Peng Chan , Shouri Hu

We study a stochastic multi-armed bandit setting where arms are partitioned into known clusters, such that the mean rewards of arms within a cluster differ by at most a known threshold. While the clustering structure is known a priori, the…

Machine Learning · Computer Science 2025-08-20 Aakash Gore , Prasanna Chaporkar

We address the problem of best arm identification (BAI) with a fixed budget for two-armed Gaussian bandits. In BAI, given multiple arms, we aim to find the best arm, an arm with the highest expected reward, through an adaptive experiment.…

Machine Learning · Computer Science 2024-03-19 Masahiro Kato

We study fixed-confidence best arm identification in generalized linear bandits under a hybrid feedback model: at each round, the learner may query either (i) absolute reward feedback from a single arm or (ii) relative (dueling) feedback…

Artificial Intelligence · Computer Science 2026-05-08 Qirun Zeng , Xuchuang Wang , Jiayi Shen , Xutong Liu , Fang Kong , Jinhang Zuo