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Large language models (LLMs) exhibit diverse response behaviors, costs, and strengths, making it challenging to select the most suitable LLM for a given user query. We study the problem of adaptive multi-LLM selection in an online setting,…

Machine Learning · Computer Science 2025-06-24 Manhin Poon , XiangXiang Dai , Xutong Liu , Fang Kong , John C. S. Lui , Jinhang Zuo

We examine a multi-armed bandit problem with contextual information, where the objective is to ensure that each arm receives a minimum aggregated reward across contexts while simultaneously maximizing the total cumulative reward. This…

Machine Learning · Computer Science 2025-10-15 Ahmed Ben Yahmed , Hafedh El Ferchichi , Marc Abeille , Vianney Perchet

We consider a sequential assortment selection problem where the user choice is given by a multinomial logit (MNL) choice model whose parameters are unknown. In each period, the learning agent observes a $d$-dimensional contextual…

Machine Learning · Statistics 2021-03-26 Min-hwan Oh , Garud Iyengar

In many sequential decision-making problems, the individuals are split into several batches and the decision-maker is only allowed to change her policy at the end of batches. These batch problems have a large number of applications, ranging…

Machine Learning · Computer Science 2021-02-26 Quanquan Gu , Amin Karbasi , Khashayar Khosravi , Vahab Mirrokni , Dongruo Zhou

We address the problem of learning in an online, bandit setting where the learner must repeatedly select among $K$ actions, but only receives partial feedback based on its choices. We establish two new facts: First, using a new algorithm…

Machine Learning · Computer Science 2011-10-28 Alina Beygelzimer , John Langford , Lihong Li , Lev Reyzin , Robert E. Schapire

Contextual bandit algorithms are increasingly replacing non-adaptive A/B tests in e-commerce, healthcare, and policymaking because they can both improve outcomes for study participants and increase the chance of identifying good or even…

Machine Learning · Statistics 2021-06-02 Aurélien Bibaut , Antoine Chambaz , Maria Dimakopoulou , Nathan Kallus , Mark van der Laan

Learning effective negotiation strategies poses two key challenges: the exploration-exploitation dilemma and dealing with large action spaces. However, there is an absence of learning-based approaches that effectively address these…

Artificial Intelligence · Computer Science 2024-07-02 Yexin Li , Zhancun Mu , Siyuan Qi

We introduce the problem of model selection for contextual bandits, where a learner must adapt to the complexity of the optimal policy while balancing exploration and exploitation. Our main result is a new model selection guarantee for…

Machine Learning · Computer Science 2019-11-15 Dylan J. Foster , Akshay Krishnamurthy , Haipeng Luo

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

Contextual bandits are widely used in Internet services from news recommendation to advertising, and to Web search. Generalized linear models (logistical regression in particular) have demonstrated stronger performance than linear models in…

Machine Learning · Computer Science 2017-06-20 Lihong Li , Yu Lu , Dengyong Zhou

We study the problem of selecting a small, representative action subset from an extremely large action space shared across a family of reinforcement learning (RL) environments -- a fundamental challenge in applications like inventory…

Machine Learning · Computer Science 2025-12-01 Quan Zhou , Shie Mannor

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 contextual linear bandits over networks, a class of sequential decision-making problems where learning occurs simultaneously across multiple locations and the reward distributions share structural similarities while also…

Machine Learning · Computer Science 2025-08-26 Chuyun Deng , Huiwen Jia

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

The bandit paradigm provides a unified modeling framework for problems that require decision-making under uncertainty. Because many business metrics can be viewed as rewards (a.k.a. utilities) that result from actions, bandit algorithms…

Machine Learning · Computer Science 2023-02-03 Bram van den Akker , Olivier Jeunen , Ying Li , Ben London , Zahra Nazari , Devesh Parekh

This paper is a scoping study to identify current methods used in handling sparse data with contextual bandits in web settings. The area is highly current and state of the art methods are identified. The years 2017-2020 are investigated,…

Machine Learning · Computer Science 2021-05-07 Björn H Eriksson

We consider contextual bandits with linear constraints (CBwLC), a variant of contextual bandits in which the algorithm consumes multiple resources subject to linear constraints on total consumption. This problem generalizes contextual…

Machine Learning · Computer Science 2024-11-27 Aleksandrs Slivkins , Xingyu Zhou , Karthik Abinav Sankararaman , Dylan J. Foster

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 Causal Bandit is a variant of the classic Bandit problem where an agent must identify the best action in a sequential decision-making process, where the reward distribution of the actions displays a non-trivial dependence structure that…

Artificial Intelligence · Computer Science 2022-09-30 Arnoud A. W. M. de Kroon , Danielle Belgrave , Joris M. Mooij

In recent years, preference-based human feedback mechanisms have become essential for enhancing model performance across diverse applications, including conversational AI systems such as ChatGPT. However, existing approaches often neglect…

Artificial Intelligence · Computer Science 2025-02-14 Raihan Seraj , Lili Meng , Tristan Sylvain