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Contextual multi-armed bandits are classical models in reinforcement learning for sequential decision-making associated with individual information. A widely-used policy for bandits is Thompson Sampling, where samples from a data-driven…

Machine Learning · Statistics 2021-11-30 Hongju Park , Mohamad Kazem Shirani Faradonbeh

Consider a nonparametric contextual multi-arm bandit problem where each arm $a \in [K]$ is associated to a nonparametric reward function $f_a: [0,1] \to \mathbb{R}$ mapping from contexts to the expected reward. Suppose that there is a large…

Machine Learning · Computer Science 2019-08-06 Nirandika Wanigasekara , Christina Lee Yu

We study the best-arm identification problem with fixed confidence when contextual (covariate) information is available in stochastic bandits. Although we can use contextual information in each round, we are interested in the marginalized…

Machine Learning · Computer Science 2024-02-27 Masahiro Kato , Kaito Ariu

We study the adversarial multi-armed bandit problem and create a completely online algorithmic framework that is invariant under arbitrary translations and scales of the arm losses. We study the expected performance of our algorithm against…

Machine Learning · Computer Science 2021-09-21 Kaan Gokcesu , Hakan Gokcesu

We study linear contextual bandits with access to a large, confounded, offline dataset that was sampled from some fixed policy. We show that this problem is closely related to a variant of the bandit problem with side information. We…

Machine Learning · Computer Science 2021-08-11 Guy Tennenholtz , Uri Shalit , Shie Mannor , Yonathan Efroni

In this paper, we propose a cost-aware cascading bandits model, a new variant of multi-armed ban- dits with cascading feedback, by considering the random cost of pulling arms. In each step, the learning agent chooses an ordered list of…

Machine Learning · Computer Science 2018-05-23 Ruida Zhou , Chao Gan , Jing Yan , Cong Shen

For traffic routing platforms, the choice of which route to recommend to a user depends on the congestion on these routes -- indeed, an individual's utility depends on the number of people using the recommended route at that instance.…

Machine Learning · Computer Science 2023-01-24 Pranjal Awasthi , Kush Bhatia , Sreenivas Gollapudi , Kostas Kollias

We consider the adversarial linear contextual bandit problem, where the loss vectors are selected fully adversarially and the per-round action set (i.e. the context) is drawn from a fixed distribution. Existing methods for this problem…

Machine Learning · Computer Science 2023-09-06 Haolin Liu , Chen-Yu Wei , Julian Zimmert

We consider the problem of designing contextual bandit algorithms in the ``cross-learning'' setting of Balseiro et al., where the learner observes the loss for the action they play in all possible contexts, not just the context of the…

Machine Learning · Computer Science 2024-01-04 Jon Schneider , Julian Zimmert

The problem of multi-armed bandits (MAB) asks to make sequential decisions while balancing between exploitation and exploration, and have been successfully applied to a wide range of practical scenarios. Various algorithms have been…

Machine Learning · Computer Science 2022-02-24 Xiaojin Zhang , Shuai Li , Weiwen Liu , Shengyu Zhang

We study the problem of learning 'good' interventions in a stochastic environment modeled by its underlying causal graph. Good interventions refer to interventions that maximize rewards. Specifically, we consider the setting of a…

Machine Learning · Computer Science 2024-01-17 Fateme Jamshidi , Jalal Etesami , Negar Kiyavash

Strategic behavior against sequential learning methods, such as "click framing" in real recommendation systems, have been widely observed. Motivated by such behavior we study the problem of combinatorial multi-armed bandits (CMAB) under…

Machine Learning · Computer Science 2021-11-22 Jing Dong , Ke Li , Shuai Li , Baoxiang Wang

We study the linear contextual bandit problem in the presence of adversarial corruption, where the reward at each round is corrupted by an adversary, and the corruption level (i.e., the sum of corruption magnitudes over the horizon) is…

Machine Learning · Computer Science 2022-07-12 Jiafan He , Dongruo Zhou , Tong Zhang , Quanquan Gu

We consider the kernelized contextual bandit problem with a large feature space. This problem involves $K$ arms, and the goal of the forecaster is to maximize the cumulative rewards through learning the relationship between the contexts and…

Machine Learning · Statistics 2025-05-21 Shogo Iwazaki , Junpei Komiyama , Masaaki Imaizumi

Learning good interventions in a causal graph can be modelled as a stochastic multi-armed bandit problem with side-information. First, we study this problem when interventions are more expensive than observations and a budget is specified.…

Machine Learning · Computer Science 2020-12-15 Vineet Nair , Vishakha Patil , Gaurav Sinha

Contextual bandit algorithms provide principled online learning solutions to balance the exploitation-exploration trade-off in various applications such as recommender systems. However, the learning speed of the traditional contextual…

Machine Learning · Computer Science 2020-01-28 Xiaoying Zhang , Hong Xie , Hang Li , John C. S. Lui

We introduce and study a new class of stochastic bandit problems, referred to as predictive bandits. In each round, the decision maker first decides whether to gather information about the rewards of particular arms (so that their rewards…

Machine Learning · Computer Science 2020-04-03 Simon Lindståhl , Alexandre Proutiere , Andreas Johnsson

We provide the first oracle efficient sublinear regret algorithms for adversarial versions of the contextual bandit problem. In this problem, the learner repeatedly makes an action on the basis of a context and receives reward for the…

Machine Learning · Computer Science 2016-02-09 Vasilis Syrgkanis , Akshay Krishnamurthy , Robert E. Schapire

We study bandit best-arm identification with arbitrary and potentially adversarial rewards. A simple random uniform learner obtains the optimal rate of error in the adversarial scenario. However, this type of strategy is suboptimal when the…

Machine Learning · Statistics 2026-04-17 Yasin Abbasi-Yadkori , Peter L. Bartlett , Victor Gabillon , Alan Malek , Michal Valko

Bandits with covariates, a.k.a. contextual bandits, address situations where optimal actions (or arms) at a given time $t$, depend on a context $x_t$, e.g., a new patient's medical history, a consumer's past purchases. While it is…

Machine Learning · Statistics 2021-02-23 Joseph Suk , Samory Kpotufe