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We revisit the study of optimal regret rates in bandit combinatorial optimization---a fundamental framework for sequential decision making under uncertainty that abstracts numerous combinatorial prediction problems. We prove that the…

Machine Learning · Computer Science 2017-02-27 Alon Cohen , Tamir Hazan , Tomer Koren

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

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 consider the problem of combining and learning over a set of adversarial bandit algorithms with the goal of adaptively tracking the best one on the fly. The CORRAL algorithm of Agarwal et al. (2017) and its variants (Foster et al.,…

Machine Learning · Computer Science 2022-02-15 Haipeng Luo , Mengxiao Zhang , Peng Zhao , Zhi-Hua Zhou

Contextual bandit with linear reward functions is among one of the most extensively studied models in bandit and online learning research. Recently, there has been increasing interest in designing \emph{locally private} linear contextual…

Machine Learning · Statistics 2024-04-16 Jiachun Li , David Simchi-Levi , Yining Wang

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

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

Stochastic linear bandits are a fundamental model for sequential decision making, where an agent selects a vector-valued action and receives a noisy reward with expected value given by an unknown linear function. Although well studied in…

Machine Learning · Computer Science 2025-06-23 Bruce Huang , Ruida Zhou , Lin F. Yang , Suhas Diggavi

In this paper, we study the problem of stochastic linear bandits with finite action sets. Most of existing work assume the payoffs are bounded or sub-Gaussian, which may be violated in some scenarios such as financial markets. To settle…

Machine Learning · Computer Science 2020-04-29 Bo Xue , Guanghui Wang , Yimu Wang , Lijun Zhang

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

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 online inverse linear optimization, a learner observes time-varying sets of feasible actions and an agent's optimal actions, selected by solving linear optimization over the feasible actions. The learner sequentially makes predictions of…

Machine Learning · Computer Science 2025-05-23 Shinsaku Sakaue , Taira Tsuchiya , Han Bao , Taihei Oki

This paper proposes a linear bandit algorithm that is adaptive to environments at two different levels of hierarchy. At the higher level, the proposed algorithm adapts to a variety of types of environments. More precisely, it achieves…

Machine Learning · Computer Science 2023-02-27 Shinji Ito , Kei Takemura

Motivated by applications in clinical trials and finance, we study the problem of online convex optimization (with bandit feedback) where the decision maker is risk-averse. We provide two algorithms to solve this problem. The first one is a…

Machine Learning · Computer Science 2018-10-02 Adrian Rivera Cardoso , Huan Xu

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

Regret bounds in online learning compare the player's performance to $L^*$, the optimal performance in hindsight with a fixed strategy. Typically such bounds scale with the square root of the time horizon $T$. The more refined concept of…

Machine Learning · Computer Science 2018-02-12 Zeyuan Allen-Zhu , Sébastien Bubeck , Yuanzhi Li

In this work, we study the online convex optimization problem with curved losses and delayed feedback. When losses are strongly convex, existing approaches obtain regret bounds of order $d_{\max} \ln T$, where $d_{\max}$ is the maximum…

Machine Learning · Computer Science 2025-06-10 Hao Qiu , Emmanuel Esposito , Mengxiao Zhang

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

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 consider a linear stochastic bandit problem involving $M$ agents that can collaborate via a central server to minimize regret. A fraction $\alpha$ of these agents are adversarial and can act arbitrarily, leading to the following tension:…

Machine Learning · Computer Science 2022-06-08 Aritra Mitra , Arman Adibi , George J. Pappas , Hamed Hassani