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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

Recent results in supervised learning suggest that while overparameterized models have the capacity to overfit, they in fact generalize quite well. We ask whether the same phenomenon occurs for offline contextual bandits. Our results are…

Machine Learning · Computer Science 2021-06-17 David Brandfonbrener , William F. Whitney , Rajesh Ranganath , Joan Bruna

Contextual bandits are widely-used in the study of learning-based control policies for finite action spaces. While the problem is well-studied for bandits with perfectly observed context vectors, little is known about the case of…

Machine Learning · Statistics 2022-02-03 Hongju Park , Mohamad Kazem Shirani Faradonbeh

Understanding a decision-maker's priorities by observing their behavior is critical for transparency and accountability in decision processes, such as in healthcare. Though conventional approaches to policy learning almost invariably assume…

Machine Learning · Computer Science 2022-06-09 Alihan Hüyük , Daniel Jarrett , Mihaela van der Schaar

Efficient exploration is a crucial challenge in deep reinforcement learning. Several methods, such as behavioral priors, are able to leverage offline data in order to efficiently accelerate reinforcement learning on complex tasks. However,…

Machine Learning · Computer Science 2022-09-01 Marco Bagatella , Sammy Christen , Otmar Hilliges

Contextual bandit algorithms often estimate reward models to inform decision-making. However, true rewards can contain action-independent redundancies that are not relevant for decision-making. We show it is more data-efficient to estimate…

Machine Learning · Computer Science 2023-02-27 Aldo Gael Carranza , Sanath Kumar Krishnamurthy , Susan Athey

Methods for sequential decision-making are often built upon a foundational assumption that the underlying decision process is stationary. This limits the application of such methods because real-world problems are often subject to changes…

Machine Learning · Computer Science 2023-01-26 Yash Chandak , Shiv Shankar , Nathaniel D. Bastian , Bruno Castro da Silva , Emma Brunskil , Philip S. Thomas

A key goal in stochastic contextual linear bandits is to efficiently learn a near-optimal policy. Prior algorithms for this problem learn a policy by strategically sampling actions but naively (passively) sampling contexts from the…

Machine Learning · Computer Science 2026-05-26 Emma Brunskill , Ishani Karmarkar , Zhaoqi Li

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

Automated decision-making algorithms drive applications such as recommendation systems and search engines. These algorithms often rely on off-policy contextual bandits or off-policy learning (OPL). Conventionally, OPL selects actions that…

We consider off-policy evaluation in the contextual bandit setting for the purpose of obtaining a robust off-policy selection strategy, where the selection strategy is evaluated based on the value of the chosen policy in a set of proposal…

Machine Learning · Computer Science 2022-03-22 Ilja Kuzborskij , Claire Vernade , András György , Csaba Szepesvári

Contextual Bandits is one of the widely popular techniques used in applications such as personalization, recommendation systems, mobile health, causal marketing etc . As a dynamic approach, it can be more efficient than standard A/B testing…

Machine Learning · Computer Science 2022-02-03 Praneet Dutta , Joe Cheuk , Jonathan S Kim , Massimo Mascaro

Bandit algorithms sequentially accumulate data using adaptive sampling policies, offering flexibility for real-world applications. However, excessive sampling can be costly, motivating the devolopment of early stopping methods and reliable…

Statistics Theory · Mathematics 2025-02-06 Zihan Cui

We create a computationally tractable algorithm for contextual bandits with continuous actions having unknown structure. Our reduction-style algorithm composes with most supervised learning representations. We prove that it works in a…

Machine Learning · Computer Science 2020-12-07 Maryam Majzoubi , Chicheng Zhang , Rajan Chari , Akshay Krishnamurthy , John Langford , Aleksandrs Slivkins

Offline contextual bandits allow one to learn policies from historical/offline data without requiring online interaction. However, offline policy optimization that maximizes overall expected rewards can unintentionally amplify the reward…

Machine Learning · Computer Science 2026-01-07 Yihong Guo , Junjie Luo , Guodong Gao , Ritu Agarwal , Anqi Liu

In this paper, we address the contextual dueling bandit problem by proposing variance-aware algorithms that leverage neural networks to approximate nonlinear utility functions. Our approach employs a \textit{variance-aware exploration…

Machine Learning · Computer Science 2026-05-12 Youngmin Oh , Jinje Park , Taejin Paik , Jaemin Park

Thompson sampling has proven effective across a wide range of stationary bandit environments. However, as we demonstrate in this paper, it can perform poorly when applied to non-stationary environments. We attribute such failures to the…

Machine Learning · Computer Science 2025-05-06 Yueyang Liu , Xu Kuang , Benjamin Van Roy

We study the offline contextual bandit problem, where we aim to acquire an optimal policy using observational data. However, this data usually contains two deficiencies: (i) some variables that confound actions are not observed, and (ii)…

Machine Learning · Computer Science 2023-03-21 Siyu Chen , Yitan Wang , Zhaoran Wang , Zhuoran Yang

Leveraging offline data is an attractive way to accelerate online sequential decision-making. However, it is crucial to account for latent states in users or environments in the offline data, and latent bandits form a compelling model for…

Machine Learning · Computer Science 2025-09-03 Chinmaya Kausik , Kevin Tan , Ambuj Tewari

We design and implement an adaptive experiment (a ``contextual bandit'') to learn a targeted treatment assignment policy, where the goal is to use a participant's survey responses to determine which charity to expose them to in a donation…