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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 a stochastic bandit problem with a possibly infinite number of arms. We write $p^*$ for the proportion of optimal arms and $\Delta$ for the minimal mean-gap between optimal and sub-optimal arms. We characterize the optimal…

Machine Learning · Computer Science 2021-11-08 Rianne de Heide , James Cheshire , Pierre Ménard , Alexandra Carpentier

We consider the fixed-confidence best arm identification (FC-BAI) problem in the Bayesian setting. This problem aims to find the arm of the largest mean with a fixed confidence level when the bandit model has been sampled from the known…

Machine Learning · Statistics 2024-06-25 Kyoungseok Jang , Junpei Komiyama , Kazutoshi Yamazaki

This paper studies active learning in the context of robust statistics. Specifically, we propose a variant of the Best Arm Identification problem for \emph{contaminated bandits}, where each arm pull has probability $\varepsilon$ of…

Statistics Theory · Mathematics 2021-11-16 Jason Altschuler , Victor-Emmanuel Brunel , Alan Malek

In this work, we address the open problem of finding low-complexity near-optimal multi-armed bandit algorithms for sequential decision making problems. Existing bandit algorithms are either sub-optimal and computationally simple (e.g.,…

Machine Learning · Computer Science 2018-04-18 Fang Liu , Sinong Wang , Swapna Buccapatnam , Ness Shroff

Clustering has become an indispensable tool in the presence of increasingly large and complex data sets. Most clustering algorithms depend, either explicitly or implicitly, on the sampled density. However, estimated densities are fragile…

Chemical Physics · Physics 2023-08-21 Moritz Thürlemann , Sereina Riniker

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 propose algorithms based on a multi-level Thompson sampling scheme, for the stochastic multi-armed bandit and its contextual variant with linear expected rewards, in the setting where arms are clustered. We show, both theoretically and…

Machine Learning · Computer Science 2022-06-16 Emil Carlsson , Devdatt Dubhashi , Fredrik D. Johansson

We address the problem of identifying the optimal policy with a fixed confidence level in a multi-armed bandit setup, when \emph{the arms are subject to linear constraints}. Unlike the standard best-arm identification problem which is well…

Machine Learning · Computer Science 2024-01-26 Emil Carlsson , Debabrota Basu , Fredrik D. Johansson , Devdatt Dubhashi

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

For the stochastic multi-armed bandit (MAB) problem from a constrained model that generalizes the classical one, we show that an asymptotic optimality is achievable by a simple strategy extended from the $\epsilon_t$-greedy strategy. We…

Optimization and Control · Mathematics 2018-05-04 Hyeong Soo Chang

We study pure exploration with infinitely many bandit arms generated i.i.d. from an unknown distribution. Our goal is to efficiently select a single high quality arm whose average reward is, with probability $1-\delta$, within $\varepsilon$…

Machine Learning · Computer Science 2023-06-06 Xiao-Yue Gong , Mark Sellke

We consider the problem of identifying any $k$ out of the best $m$ arms in an $n$-armed stochastic multi-armed bandit. Framed in the PAC setting, this particular problem generalises both the problem of `best subset selection' and that of…

Machine Learning · Computer Science 2019-01-25 Arghya Roy Chaudhuri , Shivaram Kalyanakrishnan

This paper considers the problem of maximizing an expectation function over a finite set, or finite-arm bandit problem. We first propose a naive stochastic bandit algorithm for obtaining a probably approximately correct (PAC) solution to…

Optimization and Control · Mathematics 2022-06-16 Marie Billaud-Friess , Arthur Macherey , Anthony Nouy , Clémentine Prieur

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 develop a general framework for clustering and distribution matching problems with bandit feedback. We consider a $K$-armed bandit model where some subset of $K$ arms is partitioned into $M$ groups. Within each group, the random variable…

Machine Learning · Computer Science 2025-02-12 Recep Can Yavas , Yuqi Huang , Vincent Y. F. Tan , Jonathan Scarlett

We propose online algorithms for sequential learning in the contextual multi-armed bandit setting. Our approach is to partition the context space and then optimally combine all of the possible mappings between the partition regions and the…

Machine Learning · Computer Science 2017-12-11 Mohammadreza Mohaghegh Neyshabouri , Kaan Gokcesu , Huseyin Ozkan , Suleyman S. Kozat

This paper proposes near-optimal algorithms for the pure-exploration linear bandit problem in the fixed confidence and fixed budget settings. Leveraging ideas from the theory of suprema of empirical processes, we provide an algorithm whose…

Machine Learning · Computer Science 2020-06-23 Julian Katz-Samuels , Lalit Jain , Zohar Karnin , Kevin Jamieson

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

Motivated by the task of hyperparameter optimization, we introduce the non-stochastic best-arm identification problem. Within the multi-armed bandit literature, the cumulative regret objective enjoys algorithms and analyses for both the…

Machine Learning · Computer Science 2015-03-02 Kevin Jamieson , Ameet Talwalkar