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Recently, bandit optimization has received significant attention in real-world safety-critical systems that involve repeated interactions with humans. While there exist various algorithms with performance guarantees in the literature,…

Machine Learning · Computer Science 2023-11-13 Amirhossein Afsharrad , Ahmadreza Moradipari , Sanjay Lall

Motivated by practical needs such as large-scale learning, we study the impact of adaptivity constraints to linear contextual bandits, a central problem in online active learning. We consider two popular limited adaptivity models in…

Machine Learning · Computer Science 2021-04-26 Yufei Ruan , Jiaqi Yang , Yuan Zhou

We study the stochastic multi-armed bandits problem in the presence of adversarial corruption. We present a new algorithm for this problem whose regret is nearly optimal, substantially improving upon previous work. Our algorithm is agnostic…

Machine Learning · Computer Science 2019-03-29 Anupam Gupta , Tomer Koren , Kunal Talwar

We consider a contextual bandit problem with $S$ contexts and $K$ actions. In each round $t=1,2,\dots$, the learner observes a random context and chooses an action based on its past experience. The learner then observes a random reward…

Machine Learning · Computer Science 2023-11-29 Chung-Wei Lee , Qinghua Liu , Yasin Abbasi-Yadkori , Chi Jin , Tor Lattimore , Csaba Szepesvári

The safe linear bandit problem is a version of the classical stochastic linear bandit problem where the learner's actions must satisfy an uncertain constraint at all rounds. Due its applicability to many real-world settings, this problem…

Machine Learning · Computer Science 2024-03-13 Spencer Hutchinson , Berkay Turan , Mahnoosh Alizadeh

Contextual bandit algorithms are sensitive to the estimation method of the outcome model as well as the exploration method used, particularly in the presence of rich heterogeneity or complex outcome models, which can lead to difficult…

Machine Learning · Statistics 2018-12-18 Maria Dimakopoulou , Zhengyuan Zhou , Susan Athey , Guido Imbens

We study the stochastic contextual bandit with knapsacks (CBwK) problem, where each action, taken upon a context, not only leads to a random reward but also costs a random resource consumption in a vector form. The challenge is to maximize…

Machine Learning · Computer Science 2023-02-23 Yuxuan Han , Jialin Zeng , Yang Wang , Yang Xiang , Jiheng Zhang

In the dynamic landscape of online businesses, recommender systems are pivotal in enhancing user experiences. While traditional approaches have relied on static supervised learning, the quest for adaptive, user-centric recommendations has…

Information Retrieval · Computer Science 2023-12-22 Yikun Ban , Yunzhe Qi , Jingrui He

Motivated by applications in online bidding and sleeping bandits, we examine the problem of contextual bandits with cross learning, where the learner observes the loss associated with the action across all possible contexts, not just the…

Machine Learning · Computer Science 2025-01-27 Ruiyuan Huang , Zengfeng Huang

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

Recently, several studies (Zhou et al., 2021a; Zhang et al., 2021b; Kim et al., 2021; Zhou and Gu, 2022) have provided variance-dependent regret bounds for linear contextual bandits, which interpolates the regret for the worst-case regime…

Machine Learning · Computer Science 2023-02-22 Heyang Zhao , Jiafan He , Dongruo Zhou , Tong Zhang , Quanquan Gu

Contextual bandits can solve a huge range of real-world problems. However, current popular algorithms to solve them either rely on linear models, or unreliable uncertainty estimation in non-linear models, which are required to deal with the…

Machine Learning · Computer Science 2023-02-01 Adam Elwood , Marco Leonardi , Ashraf Mohamed , Alessandro Rozza

Effective solving of constraint problems often requires choosing good or specific search heuristics. However, choosing or designing a good search heuristic is non-trivial and is often a manual process. In this paper, rather than manually…

Artificial Intelligence · Computer Science 2018-05-11 Wei Xia , Roland H. C. Yap

In the contextual linear bandit setting, algorithms built on the optimism principle fail to exploit the structure of the problem and have been shown to be asymptotically suboptimal. In this paper, we follow recent approaches of deriving…

Machine Learning · Computer Science 2020-11-23 Andrea Tirinzoni , Matteo Pirotta , Marcello Restelli , Alessandro Lazaric

The contextual bandit problem, which is a type of reinforcement learning tasks, provides an effective framework for solving challenges in recommendation systems, such as satisfying real-time requirements, enabling personalization,…

Machine Learning · Computer Science 2025-01-16 Shogo Ito , Tatsuji Takahashi , Yu Kono

We propose an algorithm for non-stationary kernel bandits that does not require prior knowledge of the degree of non-stationarity. The algorithm follows randomized strategies obtained by solving optimization problems that balance…

Machine Learning · Statistics 2023-02-21 Kihyuk Hong , Yuhang Li , Ambuj Tewari

A major challenge in contextual bandits is to design general-purpose algorithms that are both practically useful and theoretically well-founded. We present a new technique that has the empirical and computational advantages of…

Machine Learning · Computer Science 2018-03-06 Dylan J. Foster , Alekh Agarwal , Miroslav Dudík , Haipeng Luo , Robert E. Schapire

We consider the neural contextual bandit problem. In contrast to the existing work which primarily focuses on ReLU neural nets, we consider a general set of smooth activation functions. Under this more general setting, (i) we derive…

Machine Learning · Statistics 2022-06-02 Sudeep Salgia , Sattar Vakili , Qing Zhao

Typical contextual bandit algorithms assume that the rewards at each round lie in some fixed range $[0, R]$, and their regret scales polynomially with this reward range $R$. However, many practical scenarios naturally involve heavy-tailed…

Machine Learning · Statistics 2025-02-05 Chenlu Ye , Yujia Jin , Alekh Agarwal , Tong Zhang

We study contextual bandits with budget and time constraints, referred to as constrained contextual bandits.The time and budget constraints significantly complicate the exploration and exploitation tradeoff because they introduce complex…

Machine Learning · Computer Science 2015-10-20 Huasen Wu , R. Srikant , Xin Liu , Chong Jiang