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Stochastic Rank-One Bandits (Katarya et al, (2017a,b)) are a simple framework for regret minimization problems over rank-one matrices of arms. The initially proposed algorithms are proved to have logarithmic regret, but do not match the…

Machine Learning · Statistics 2019-12-09 Cindy Trinh , Emilie Kaufmann , Claire Vernade , Richard Combes

Much of the literature on optimal design of bandit algorithms is based on minimization of expected regret. It is well known that designs that are optimal over certain exponential families can achieve expected regret that grows…

Machine Learning · Computer Science 2024-11-14 Lin Fan , Peter W. Glynn

The Competing Bandits framework is a recently emerging area that integrates multi-armed bandits in online learning with stable matching in game theory. While conventional models assume that all players and arms are constantly available, in…

Machine Learning · Computer Science 2026-03-23 Shinnosuke Uba , Yutaro Yamaguchi

This work studies linear bandits under a new notion of gap-adjusted misspecification and is an extension of Liu et al. (2023). When the underlying reward function is not linear, existing linear bandits work usually relies on a uniform…

Machine Learning · Computer Science 2025-01-10 Chong Liu , Dan Qiao , Ming Yin , Ilija Bogunovic , Yu-Xiang Wang

We study dynamic regret minimization in unconstrained adversarial linear bandit problems. In this setting, a learner must minimize the cumulative loss relative to an arbitrary sequence of comparators…

Machine Learning · Computer Science 2026-03-30 Alberto Rumi , Andrew Jacobsen , Nicolò Cesa-Bianchi , Fabio Vitale

In many applications, e.g. in healthcare and e-commerce, the goal of a contextual bandit may be to learn an optimal treatment assignment policy at the end of the experiment. That is, to minimize simple regret. However, this objective…

Machine Learning · Computer Science 2023-11-06 Sanath Kumar Krishnamurthy , Ruohan Zhan , Susan Athey , Emma Brunskill

We study the contextual multi-armed bandit problem with a finite context space (a.k.a. subpopulations), where the learner recommends a best action for each context and is evaluated by context-weighted simple regret. Our guarantees are…

Machine Learning · Computer Science 2026-05-20 Mohammad Shahverdikondori , Jalal Etesami , Negar Kiyavash

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 study the multi-agent multi-armed bandit (MAMAB) problem, where $m$ agents are factored into $\rho$ overlapping groups. Each group represents a hyperedge, forming a hypergraph over the agents. At each round of interaction, the learner…

Machine Learning · Computer Science 2023-12-27 Tianyuan Jin , Hao-Lun Hsu , William Chang , Pan Xu

We consider the restless Markov bandit problem, in which the state of each arm evolves according to a Markov process independently of the learner's actions. We suggest an algorithm that after $T$ steps achieves $\tilde{O}(\sqrt{T})$ regret…

Machine Learning · Computer Science 2012-10-23 Ronald Ortner , Daniil Ryabko , Peter Auer , Rémi Munos

We study a decentralized cooperative multi-agent multi-armed bandit problem with $K$ arms and $N$ agents connected over a network. In our model, each arm's reward distribution is same for all agents, and rewards are drawn independently…

Machine Learning · Statistics 2020-10-29 Anusha Lalitha , Andrea Goldsmith

In this paper, we introduce a multi-armed bandit problem termed max-min grouped bandits, in which the arms are arranged in possibly-overlapping groups, and the goal is to find the group whose worst arm has the highest mean reward. This…

Machine Learning · Statistics 2022-03-16 Zhenlin Wang , Jonathan Scarlett

In the classical multi-armed bandit problem, instance-dependent algorithms attain improved performance on "easy" problems with a gap between the best and second-best arm. Are similar guarantees possible for contextual bandits? While…

Machine Learning · Computer Science 2020-10-08 Dylan J. Foster , Alexander Rakhlin , David Simchi-Levi , Yunzong Xu

Multi-objective bandits have attracted increasing attention for their broad applicability, with \(d\)-dimensional reward vectors inducing Pareto regret. There has been a subtle debate over whether this added structure makes the problem…

Machine Learning · Computer Science 2026-05-08 Changkun Guan , Mengfan Xu

We investigate the regret-minimisation problem in a multi-armed bandit setting with arbitrary corruptions. Similar to the classical setup, the agent receives rewards generated independently from the distribution of the arm chosen at each…

Machine Learning · Statistics 2023-09-29 Shubhada Agrawal , Timothée Mathieu , Debabrota Basu , Odalric-Ambrym Maillard

We study a generalization of the multi-armed bandit problem with multiple plays where there is a cost associated with pulling each arm and the agent has a budget at each time that dictates how much she can expect to spend. We derive an…

Machine Learning · Statistics 2019-09-13 Alexander Luedtke , Emilie Kaufmann , Antoine Chambaz

We consider a policy gradient algorithm applied to a finite-arm bandit problem with Bernoulli rewards. We allow learning rates to depend on the current state of the algorithm, rather than use a deterministic time-decreasing learning rate.…

Machine Learning · Computer Science 2021-09-24 Denis Denisov , Neil Walton

We investigate a Bayesian $k$-armed bandit problem in the \emph{many-armed} regime, where $k \geq \sqrt{T}$ and $T$ represents the time horizon. Initially, and aligned with recent literature on many-armed bandit problems, we observe that…

Machine Learning · Computer Science 2024-03-21 Mohsen Bayati , Nima Hamidi , Ramesh Johari , Khashayar Khosravi

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

Learning with expert advice and multi-armed bandit are two classic online decision problems which differ on how the information is observed in each round of the game. We study a family of problems interpolating the two. For a vector…

Machine Learning · Computer Science 2023-08-07 Houshuang Chen , Yuchen He , Chihao Zhang