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The contextual bandit problem is a theoretically justified framework with wide applications in various fields. While the previous study on this problem usually requires independence between noise and contexts, our work considers a more…

Machine Learning · Computer Science 2022-09-08 Xueping Gong , Jiheng Zhang

Preference-based feedback is important for many applications where direct evaluation of a reward function is not feasible. A notable recent example arises in reinforcement learning from human feedback on large language models. For many of…

Machine Learning · Computer Science 2023-07-24 Viraj Mehta , Ojash Neopane , Vikramjeet Das , Sen Lin , Jeff Schneider , Willie Neiswanger

Contextual multi-armed bandits are a popular choice to model sequential decision-making. E.g., in a healthcare application we may perform various tests to asses a patient condition (exploration) and then decide on the best treatment to give…

Machine Learning · Computer Science 2025-04-08 Mirco Mutti , Jeongyeol Kwon , Shie Mannor , Aviv Tamar

We study contextual bandits with ancillary constraints on resources, which are common in real-world applications such as choosing ads or dynamic pricing of items. We design the first algorithm for solving these problems that handles…

Machine Learning · Computer Science 2015-08-03 Ashwinkumar Badanidiyuru , John Langford , Aleksandrs Slivkins

We study the fundamental limits of learning in contextual bandits, where a learner's rewards depend on their actions and a known context, which extends the canonical multi-armed bandit to the case where side-information is available. We are…

Machine Learning · Statistics 2023-06-13 Moise Blanchard , Steve Hanneke , Patrick Jaillet

The multi-armed bandit problem is a core framework for sequential decision-making under uncertainty, but classical algorithms often fail in environments with hidden, time-varying states that confound reward estimation and optimal action…

Machine Learning · Computer Science 2026-02-19 Jikai Jin , Kenneth Hung , Sanath Kumar Krishnamurthy , Baoyi Shi , Congshan Zhang

In this paper, we investigate the impact of context diversity on stochastic linear contextual bandits. As opposed to the previous view that contexts lead to more difficult bandit learning, we show that when the contexts are sufficiently…

Machine Learning · Computer Science 2020-03-06 Weiqiang Wu , Jing Yang , Cong Shen

Contextual bandits have become popular as they offer a middle ground between very simple approaches based on multi-armed bandits and very complex approaches using the full power of reinforcement learning. They have demonstrated success in…

Methodology · Statistics 2017-11-13 Kristjan Greenewald , Ambuj Tewari , Predrag Klasnja , Susan Murphy

We propose a contextual bandit based model to capture the learning and social welfare goals of a web platform in the presence of myopic users. By using payments to incentivize these agents to explore different items/recommendations, we show…

Machine Learning · Computer Science 2020-01-23 Priyank Agrawal , Theja Tulabandhula

Contextual bandits serve as a fundamental algorithmic framework for optimizing recommendation decisions online. Though extensive attention has been paid to tailoring contextual bandits for recommendation applications, the "herding effects"…

Machine Learning · Computer Science 2024-08-29 Luyue Xu , Liming Wang , Hong Xie , Mingqiang Zhou

Contextual bandits with linear payoffs, which are also known as linear bandits, provide a powerful alternative for solving practical problems of sequential decisions, e.g., online advertisements. In the era of big data, contextual data…

Machine Learning · Computer Science 2019-03-21 Xiaotian Yu

Contextual bandits serve as a fundamental model for many sequential decision making tasks. The most popular theoretically justified approaches are based on the optimism principle. While these algorithms can be practical, they are known to…

Machine Learning · Computer Science 2020-03-17 Botao Hao , Tor Lattimore , Csaba Szepesvari

Modern systems, such as digital platforms and service systems, increasingly rely on contextual bandits for online decision-making; however, their deployment can inadvertently create unfair exposure among arms, undermining long-term platform…

Machine Learning · Statistics 2026-02-05 Qingwen Zhang , Wenjia Wang

This paper studies semiparametric contextual bandits, a generalization of the linear stochastic bandit problem where the reward for an action is modeled as a linear function of known action features confounded by an non-linear…

Machine Learning · Statistics 2018-07-17 Akshay Krishnamurthy , Zhiwei Steven Wu , Vasilis Syrgkanis

Most contextual bandit algorithms minimize regret against the best fixed policy, a questionable benchmark for non-stationary environments that are ubiquitous in applications. In this work, we develop several efficient contextual bandit…

Machine Learning · Computer Science 2019-04-05 Haipeng Luo , Chen-Yu Wei , Alekh Agarwal , John Langford

Recent work shows that when contexts are drawn i.i.d., linear contextual bandits can be reduced to single-context linear bandits. This ``contexts are cheap" perspective is highly advantageous, as it allows for sharper finite-time analyses…

Machine Learning · Computer Science 2026-03-16 Kaan Buyukkalayci , Osama Hanna , Christina Fragouli

In production systems, contextual bandit approaches often rely on direct reward models that take both action and context as input. However, these models can suffer from confounding, making it difficult to isolate the effect of the action…

Machine Learning · Computer Science 2025-09-16 Alexandre Gilotte , Otmane Sakhi , Imad Aouali , Benjamin Heymann

Bandit learning is characterized by the tension between long-term exploration and short-term exploitation. However, as has recently been noted, in settings in which the choices of the learning algorithm correspond to important decisions…

Machine Learning · Computer Science 2018-01-11 Sampath Kannan , Jamie Morgenstern , Aaron Roth , Bo Waggoner , Zhiwei Steven Wu

Contextual multinomial logit (MNL) bandits capture many real-world assortment recommendation problems such as online retailing/advertising. However, prior work has only considered (generalized) linear value functions, which greatly limits…

Machine Learning · Computer Science 2024-02-20 Mengxiao Zhang , Haipeng Luo

In this paper, we address the stochastic contextual linear bandit problem, where a decision maker is provided a context (a random set of actions drawn from a distribution). The expected reward of each action is specified by the inner…

Machine Learning · Statistics 2023-05-30 Osama A. Hanna , Lin F. Yang , Christina Fragouli