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We study stochastic linear bandits with heavy-tailed rewards, where the rewards have a finite $(1+\epsilon)$-absolute central moment bounded by $\upsilon$ for some $\epsilon \in (0,1]$. We improve both upper and lower bounds on the minimax…

Machine Learning · Computer Science 2026-01-28 Artin Tajdini , Jonathan Scarlett , Kevin Jamieson

We study finite-armed stochastic bandits where the rewards of each arm might be correlated to those of other arms. We introduce a novel phased algorithm that exploits the given structure to build confidence sets over the parameters of the…

Machine Learning · Computer Science 2020-05-26 Andrea Tirinzoni , Alessandro Lazaric , Marcello Restelli

In this paper, we propose differentially private algorithms for the problem of stochastic linear bandits in the central, local and shuffled models. In the central model, we achieve almost the same regret as the optimal non-private…

Machine Learning · Computer Science 2022-07-08 Osama A. Hanna , Antonious M. Girgis , Christina Fragouli , Suhas Diggavi

In citep{Hazan-2008-extract}, the authors showed that the regret of online linear optimization can be bounded by the total variation of the cost vectors. In this paper, we extend this result to general online convex optimization. We first…

Machine Learning · Computer Science 2012-06-15 Tianbao Yang , Mehrdad Mahdavi , Rong Jin , Shenghuo Zhu

We study the problem of nonstochastic bandits with expert advice, extending the setting from finitely many experts to any countably infinite set: A learner aims to maximize the total reward by taking actions sequentially based on bandit…

Machine Learning · Computer Science 2021-03-29 X. Flora Meng , Tuhin Sarkar , Munther A. Dahleh

We consider the stochastic bandit problem in the sublinear space setting, where one cannot record the win-loss record for all $K$ arms. We give an algorithm using $O(1)$ words of space with regret \[ \sum_{i=1}^{K}\frac{1}{\Delta_i}\log…

Data Structures and Algorithms · Computer Science 2018-05-17 David Liau , Eric Price , Zhao Song , Ger Yang

We propose the first regret-based approach to the Graphical Bilinear Bandits problem, where $n$ agents in a graph play a stochastic bilinear bandit game with each of their neighbors. This setting reveals a combinatorial NP-hard problem that…

Machine Learning · Computer Science 2022-10-13 Geovani Rizk , Igor Colin , Albert Thomas , Rida Laraki , Yann Chevaleyre

Many works have developed no-regret algorithms for contextual bandits with function approximation, where the mean reward function over context-action pairs belongs to a function class. Although there are many approaches to this problem, one…

Machine Learning · Computer Science 2025-03-18 Aldo Pacchiano

Linear Quadratic Regulator (LQR) and Linear Quadratic Gaussian (LQG) control are foundational and extensively researched problems in optimal control. We investigate LQR and LQG problems with semi-adversarial perturbations and time-varying…

Machine Learning · Computer Science 2023-10-26 Y. Jennifer Sun , Stephen Newman , Elad Hazan

A new algorithm for regret minimization in online convex optimization is described. The regret of the algorithm after $T$ time periods is $O(\sqrt{T \log T})$ - which is the minimum possible up to a logarithmic term. In addition, the new…

Machine Learning · Computer Science 2023-07-24 Elad Hazan , Nimrod Megiddo

A stochastic combinatorial semi-bandit is an online learning problem where at each step a learning agent chooses a subset of ground items subject to constraints, and then observes stochastic weights of these items and receives their sum as…

Machine Learning · Computer Science 2017-06-08 Branislav Kveton , Zheng Wen , Azin Ashkan , Csaba Szepesvari

We present a new bandit algorithm, SAO (Stochastic and Adversarial Optimal), whose regret is, essentially, optimal both for adversarial rewards and for stochastic rewards. Specifically, SAO combines the square-root worst-case regret of Exp3…

Machine Learning · Computer Science 2012-02-22 Sebastien Bubeck , Aleksandrs Slivkins

We study best-of-both-worlds algorithms for $K$-armed linear contextual bandits. Our algorithms deliver near-optimal regret bounds in both the adversarial and stochastic regimes, without prior knowledge about the environment. In the…

Machine Learning · Computer Science 2024-02-20 Yuko Kuroki , Alberto Rumi , Taira Tsuchiya , Fabio Vitale , Nicolò Cesa-Bianchi

We consider the stochastic combinatorial semi-bandit problem with adversarial corruptions. We provide a simple combinatorial algorithm that can achieve a regret of $\tilde{O}\left(C+d^2K/\Delta_{min}\right)$ where $C$ is the total amount of…

Machine Learning · Computer Science 2021-06-15 Haike Xu , Jian Li

Bandit problems with linear or concave reward have been extensively studied, but relatively few works have studied bandits with non-concave reward. This work considers a large family of bandit problems where the unknown underlying reward…

Machine Learning · Computer Science 2021-07-12 Baihe Huang , Kaixuan Huang , Sham M. Kakade , Jason D. Lee , Qi Lei , Runzhe Wang , Jiaqi Yang

We present a new strategy for gap estimation in randomized algorithms for multiarmed bandits and combine it with the EXP3++ algorithm of Seldin and Slivkins (2014). In the stochastic regime the strategy reduces dependence of regret on a…

Machine Learning · Computer Science 2017-05-10 Yevgeny Seldin , Gábor Lugosi

Bandit convex optimisation is a fundamental framework for studying zeroth-order convex optimisation. This book covers the many tools used for this problem, including cutting plane methods, interior point methods, continuous exponential…

Optimization and Control · Mathematics 2025-11-13 Tor Lattimore

We consider a stochastic bandit problem with infinitely many arms. In this setting, the learner has no chance of trying all the arms even once and has to dedicate its limited number of samples only to a certain number of arms. All previous…

Machine Learning · Computer Science 2015-05-19 Alexandra Carpentier , Michal Valko

We study adaptive regret bounds in terms of the variation of the losses (the so-called path-length bounds) for both multi-armed bandit and more generally linear bandit. We first show that the seemingly suboptimal path-length bound of (Wei…

Machine Learning · Computer Science 2019-06-19 Sébastien Bubeck , Yuanzhi Li , Haipeng Luo , Chen-Yu Wei

We demonstrate that, in the classical non-stochastic regret minimization problem with $d$ decisions, gains and losses to be respectively maximized or minimized are fundamentally different. Indeed, by considering the additional sparsity…

Machine Learning · Computer Science 2015-11-30 Joon Kwon , Vianney Perchet