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We present the first algorithms for generalized linear contextual bandits under shuffle differential privacy and joint differential privacy. While prior work on private contextual bandits has been restricted to linear reward models -- which…

Machine Learning · Statistics 2026-04-28 Sahasrajit Sarmasarkar

We study agents communicating over an underlying network by exchanging messages, in order to optimize their individual regret in a common nonstochastic multi-armed bandit problem. We derive regret minimization algorithms that guarantee for…

Machine Learning · Computer Science 2019-11-19 Yogev Bar-On , Yishay Mansour

We consider the problem of contextual kernel bandits with stochastic contexts, where the underlying reward function belongs to a known Reproducing Kernel Hilbert Space. We study this problem under an additional constraint of Differential…

Machine Learning · Statistics 2025-07-21 Nikola Pavlovic , Sudeep Salgia , Qing Zhao

We develop a new reduction that converts any online convex optimization algorithm suffering $O(\sqrt{T})$ regret into an $\epsilon$-differentially private stochastic convex optimization algorithm with the optimal convergence rate $\tilde…

Machine Learning · Computer Science 2022-10-14 Qinzi Zhang , Hoang Tran , Ashok Cutkosky

Linear bandit algorithms yield $\tilde{\mathcal{O}}(n\sqrt{T})$ pseudo-regret bounds on compact convex action sets $\mathcal{K}\subset\mathbb{R}^n$ and two types of structural assumptions lead to better pseudo-regret bounds. When…

Machine Learning · Computer Science 2021-03-11 Thomas Kerdreux , Christophe Roux , Alexandre d'Aspremont , Sebastian Pokutta

Recently a multi-agent variant of the classical multi-armed bandit was proposed to tackle fairness issues in online learning. Inspired by a long line of work in social choice and economics, the goal is to optimize the Nash social welfare…

Machine Learning · Computer Science 2022-09-27 Matthew Jones , Huy Lê Nguyen , Thy Nguyen

We present an efficient algorithm for linear contextual bandits with adversarial losses and stochastic action sets. Our approach reduces this setting to misspecification-robust adversarial linear bandits with fixed action sets. Without…

Machine Learning · Computer Science 2025-12-16 Tim van Erven , Jack Mayo , Julia Olkhovskaya , Chen-Yu Wei

We investigate bandit convex optimization (BCO) with delayed feedback, where only the loss value of the action is revealed under an arbitrary delay. Let $n,T,\bar{d}$ denote the dimensionality, time horizon, and average delay, respectively.…

Machine Learning · Computer Science 2024-06-25 Yuanyu Wan , Chang Yao , Mingli Song , Lijun Zhang

We study the adversarial kernel bandit problem, in which the loss at each round is induced by an arbitrary bounded element of a reproducing kernel Hilbert space (RKHS). We propose an exponential-weights algorithm built on a regularized…

Machine Learning · Computer Science 2026-05-27 Yu-Jie Zhang , Hao Qiu , Jonathan Scarlett , Kevin Jamieson

We present a modified tuning of the algorithm of Zimmert and Seldin [2020] for adversarial multiarmed bandits with delayed feedback, which in addition to the minimax optimal adversarial regret guarantee shown by Zimmert and Seldin…

Machine Learning · Computer Science 2022-07-01 Saeed Masoudian , Julian Zimmert , Yevgeny Seldin

In this paper, we consider the problem of sleeping bandits with stochastic action sets and adversarial rewards. In this setting, in contrast to most work in bandits, the actions may not be available at all times. For instance, some products…

Machine Learning · Computer Science 2020-08-11 Aadirupa Saha , Pierre Gaillard , Michal Valko

In this paper, we study differentially private online learning problems in a stochastic environment under both bandit and full information feedback. For differentially private stochastic bandits, we propose both UCB and Thompson…

Machine Learning · Computer Science 2024-05-31 Bingshan Hu , Zhiming Huang , Nishant A. Mehta , Nidhi Hegde

We make significant progress toward the stochastic shortest path problem with adversarial costs and unknown transition. Specifically, we develop algorithms that achieve $\widetilde{O}(\sqrt{S^2ADT_\star K})$ regret for the full-information…

Machine Learning · Computer Science 2021-06-15 Liyu Chen , Haipeng Luo

We propose the first contextual bandit algorithm that is parameter-free, efficient, and optimal in terms of dynamic regret. Specifically, our algorithm achieves dynamic regret $\mathcal{O}(\min\{\sqrt{ST},…

Machine Learning · Computer Science 2019-06-19 Yifang Chen , Chung-Wei Lee , Haipeng Luo , Chen-Yu Wei

We study online reinforcement learning in linear Markov decision processes with adversarial losses and bandit feedback, without prior knowledge on transitions or access to simulators. We introduce two algorithms that achieve improved regret…

Machine Learning · Computer Science 2023-10-19 Haolin Liu , Chen-Yu Wei , Julian Zimmert

We consider online learning problems where the aim is to achieve regret which is efficient in the sense that it is the same order as the lowest regret amongst K experts. This is a substantially stronger requirement that achieving…

Machine Learning · Computer Science 2019-11-12 Daron Anderson , Douglas J. Leith

As sequential learning algorithms are increasingly applied to real life, ensuring data privacy while maintaining their utilities emerges as a timely question. In this context, regret minimisation in stochastic bandits under…

Machine Learning · Statistics 2025-05-12 Achraf Azize , Yulian Wu , Junya Honda , Francesco Orabona , Shinji Ito , Debabrota Basu

We provide the first algorithm for online bandit linear optimization whose regret after T rounds is of order sqrt{Td ln N} on any finite class X of N actions in d dimensions, and of order d*sqrt{T} (up to log factors) when X is infinite.…

Machine Learning · Computer Science 2012-02-15 Nicolò Cesa-Bianchi , Sham Kakade

We consider an adversarial variant of the classic $K$-armed linear contextual bandit problem where the sequence of loss functions associated with each arm are allowed to change without restriction over time. Under the assumption that the…

Machine Learning · Computer Science 2022-05-25 Gergely Neu , Julia Olkhovskaya

We consider the adversarial multi-armed bandit problem under delayed feedback. We analyze variants of the Exp3 algorithm that tune their step-size using only information (about the losses and delays) available at the time of the decisions,…

Machine Learning · Computer Science 2020-10-14 András György , Pooria Joulani