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We consider a novel stochastic multi-armed bandit setting, where playing an arm makes it unavailable for a fixed number of time slots thereafter. This models situations where reusing an arm too often is undesirable (e.g. making the same…

Machine Learning · Computer Science 2024-07-31 Soumya Basu , Rajat Sen , Sujay Sanghavi , Sanjay Shakkottai

Reinforcement learning addresses the dilemma between exploration to find profitable actions and exploitation to act according to the best observations already made. Bandit problems are one such class of problems in stateless environments…

Machine Learning · Computer Science 2012-02-20 Ananda Narayanan B , Balaraman Ravindran

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

We study federated contextual linear bandits, where $M$ agents cooperate with each other to solve a global contextual linear bandit problem with the help of a central server. We consider the asynchronous setting, where all agents work…

Machine Learning · Computer Science 2022-07-08 Jiafan He , Tianhao Wang , Yifei Min , Quanquan Gu

We study the non-stationary stochastic multi-armed bandit problem, where the reward statistics of each arm may change several times during the course of learning. The performance of a learning algorithm is evaluated in terms of their…

Machine Learning · Computer Science 2022-03-09 Yasin Abbasi-Yadkori , Andras Gyorgy , Nevena Lazic

We consider the adversarial convex bandit problem and we build the first $\mathrm{poly}(T)$-time algorithm with $\mathrm{poly}(n) \sqrt{T}$-regret for this problem. To do so we introduce three new ideas in the derivative-free optimization…

Machine Learning · Computer Science 2016-07-19 Sébastien Bubeck , Ronen Eldan , Yin Tat Lee

In this work, we develop linear bandit algorithms that automatically adapt to different environments. By plugging a novel loss estimator into the optimization problem that characterizes the instance-optimal strategy, our first algorithm not…

Machine Learning · Computer Science 2021-06-15 Chung-Wei Lee , Haipeng Luo , Chen-Yu Wei , Mengxiao Zhang , Xiaojin Zhang

This paper addresses the problem of learning to sparsify stochastic linear bandits, where a decision-maker sequentially selects actions from a high-dimensional space subject to a sparsity constraint on the number of nonzero elements in the…

Machine Learning · Computer Science 2026-05-12 Zhengmiao Wang , Ming Chi , Zhi-Wei Liu , Lintao Ye , Carla Fabiana Chiasserini

Recent growing adoption of experimentation in practice has led to a surge of attention to multiarmed bandits as a technique to reduce the opportunity cost of online experiments. In this setting, a decision-maker sequentially chooses among a…

Machine Learning · Computer Science 2022-04-04 Nima Hamidi , Mohsen Bayati

We introduce the first best-of-both-worlds algorithm for contextual combinatorial semi-bandits that simultaneously guarantees $\widetilde{\mathcal{O}}(\sqrt{T})$ regret in the adversarial regime and $\widetilde{\mathcal{O}}(\ln T)$ regret…

Machine Learning · Statistics 2026-03-27 Mengmeng Li , Philipp J. Schneider , Jelisaveta Aleksić , Daniel Kuhn

We study the problem of incentive-compatible online learning with bandit feedback. In this class of problems, the experts are self-interested agents who might misrepresent their preferences with the goal of being selected most often. The…

Machine Learning · Computer Science 2024-05-13 Julian Zimmert , Teodor V. Marinov

We investigate contextual bandits in the presence of side-observations across arms in order to design recommendation algorithms for users connected via social networks. Users in social networks respond to their friends' activity, and hence…

Machine Learning · Computer Science 2020-10-27 Rahul Singh , Fang Liu , Xin Liu , Ness Shroff

We study high-probability regret bounds for adversarial $K$-armed bandits with time-varying feedback graphs over $T$ rounds. For general strongly observable graphs, we develop an algorithm that achieves the optimal regret…

Machine Learning · Computer Science 2023-01-31 Haipeng Luo , Hanghang Tong , Mengxiao Zhang , Yuheng Zhang

This paper studies bandit convex optimization in non-stationary environments with two-point feedback, using dynamic regret as the performance measure. We propose an algorithm based on bandit mirror descent that extends naturally to…

Optimization and Control · Mathematics 2026-05-26 Chang He , Bo Jiang , Shuzhong Zhang

We study the generalized linear bandit (GLB) problem, a contextual multi-armed bandit framework that extends the classical linear model by incorporating a non-linear link function, thereby modeling a broad class of reward distributions such…

Machine Learning · Computer Science 2025-10-31 Yu-Jie Zhang , Sheng-An Xu , Peng Zhao , Masashi Sugiyama

Thompson Sampling (TS) is one of the most effective algorithms for solving contextual multi-armed bandit problems. In this paper, we propose a new algorithm, called Neural Thompson Sampling, which adapts deep neural networks for both…

Machine Learning · Computer Science 2022-01-03 Weitong Zhang , Dongruo Zhou , Lihong Li , Quanquan Gu

We study contextual bandits with low-rank structure where, in each round, if the (context, arm) pair $(i,j)\in [m]\times [n]$ is selected, the learner observes a noisy sample of the $(i,j)$-th entry of an unknown low-rank reward matrix.…

Machine Learning · Computer Science 2024-07-08 Yassir Jedra , William Réveillard , Stefan Stojanovic , Alexandre Proutiere

In this paper, we consider the stochastic multi-armed bandits problem with adversarial corruptions, where the random rewards of the arms are partially modified by an adversary to fool the algorithm. We apply the policy gradient algorithm…

Machine Learning · Computer Science 2025-02-21 Jiayuan Liu , Siwei Wang , Zhixuan Fang

We study reinforcement learning with linear function approximation and adversarially changing cost functions, a setup that has mostly been considered under simplifying assumptions such as full information feedback or exploratory…

Machine Learning · Computer Science 2023-01-31 Uri Sherman , Tomer Koren , Yishay Mansour

In the stochastic contextual low-rank matrix bandit problem, the expected reward of an action is given by the inner product between the action's feature matrix and some fixed, but initially unknown $d_1$ by $d_2$ matrix $\Theta^*$ with rank…

Machine Learning · Statistics 2024-01-17 Yue Kang , Cho-Jui Hsieh , Thomas C. M. Lee