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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

We study high-probability regret bounds for adversarial $K$-armed bandits with time-varying feedback graphs over $T$ rounds. For general strongly observable graphs, we develop an algorithm that achieves the optimal regret…

Machine Learning · Computer Science 2023-01-31 Haipeng Luo , Hanghang Tong , Mengxiao Zhang , Yuheng Zhang

We consider the problem of contextual bandits where actions are subsets of a ground set and mean rewards are modeled by an unknown monotone submodular function that belongs to a class $\mathcal{F}$. We allow time-varying matroid constraints…

Machine Learning · Computer Science 2021-12-07 Dean P. Foster , Alexander Rakhlin

Logistic Bandits have recently attracted substantial attention, by providing an uncluttered yet challenging framework for understanding the impact of non-linearity in parametrized bandits. It was shown by Faury et al. (2020) that the…

Machine Learning · Computer Science 2021-03-10 Marc Abeille , Louis Faury , Clément Calauzènes

Motivated by models of human decision making proposed to explain commonly observed deviations from conventional expected value preferences, we formulate two stochastic multi-armed bandit problems with distorted probabilities on the reward…

Machine Learning · Computer Science 2023-11-01 Ravi Kumar Kolla , Prashanth L. A. , Aditya Gopalan , Krishna Jagannathan , Michael Fu , Steve Marcus

We study the stochastic linear bandits with parameter noise model, in which the reward of action $a$ is $a^\top \theta$ where $\theta$ is sampled i.i.d. We show a regret upper bound of $\widetilde{O} (\sqrt{d T \log (K/\delta)…

Machine Learning · Computer Science 2026-05-26 Daniel Ezer , Alon Peled-Cohen , Yishay Mansour

In this work, we investigate the problem of adapting to the presence or absence of causal structure in multi-armed bandit problems. In addition to the usual reward signal, we assume the learner has access to additional variables, observed…

Machine Learning · Computer Science 2024-07-02 Ziyi Liu , Idan Attias , Daniel M. Roy

Reinforcement learning (RL) with linear function approximation has received increasing attention recently. However, existing work has focused on obtaining $\sqrt{T}$-type regret bound, where $T$ is the number of interactions with the MDP.…

Machine Learning · Computer Science 2021-02-19 Jiafan He , Dongruo Zhou , Quanquan Gu

In multi-objective decision-making with hierarchical preferences, lexicographic bandits provide a natural framework for optimizing multiple objectives in a prioritized order. In this setting, a learner repeatedly selects arms and observes…

Machine Learning · Computer Science 2025-11-11 Bo Xue , Yuanyu Wan , Zhichao Lu , Qingfu Zhang

This paper studies a non-stationary kernelized bandit (KB) problem, also called time-varying Bayesian optimization, where one seeks to minimize the regret under an unknown reward function that varies over time. In particular, we focus on a…

Machine Learning · Computer Science 2024-10-22 Shogo Iwazaki , Shion Takeno

We consider minimisation of dynamic regret in non-stationary bandits with a slowly varying property. Namely, we assume that arms' rewards are stochastic and independent over time, but that the absolute difference between the expected…

Machine Learning · Computer Science 2021-10-26 Ramakrishnan Krishnamurthy , Aditya Gopalan

For the misspecified linear Markov decision process (MLMDP) model of Jin et al. [2020], we propose an algorithm with three desirable properties. (P1) Its regret after $K$ episodes scales as $K \max \{ \varepsilon_{\text{mis}},…

Machine Learning · Computer Science 2022-03-02 Daniel Vial , Advait Parulekar , Sanjay Shakkottai , R. Srikant

Nash regret has recently emerged as a principled fairness-aware performance metric for stochastic multi-armed bandits, motivated by the Nash Social Welfare objective. Although this notion has been extended to linear bandits, existing…

Machine Learning · Computer Science 2026-02-02 Dhruv Sarkar , Nishant Pandey , Sayak Ray Chowdhury

Sequential design of experiments for optimizing a reward function in causal systems can be effectively modeled by the sequential design of interventions in causal bandits (CBs). In the existing literature on CBs, a critical assumption is…

Machine Learning · Statistics 2024-03-06 Zirui Yan , Arpan Mukherjee , Burak Varıcı , Ali Tajer

Contextual bandits are a central framework for sequential decision-making, with applications ranging from recommendation systems to clinical trials. While nonparametric methods can flexibly model complex reward structures, they suffer from…

Statistics Theory · Mathematics 2026-01-01 Wanteng Ma , T. Tony Cai

In this paper, we study a special bandit setting of online stochastic linear optimization, where only one-bit of information is revealed to the learner at each round. This problem has found many applications including online advertisement…

Machine Learning · Computer Science 2015-09-28 Lijun Zhang , Tianbao Yang , Rong Jin , Zhi-Hua Zhou

We study fairness in linear bandit problems. Starting from the notion of meritocratic fairness introduced in Joseph et al. [2016], we carry out a more refined analysis of a more general problem, achieving better performance guarantees with…

Machine Learning · Computer Science 2017-06-30 Matthew Joseph , Michael Kearns , Jamie Morgenstern , Seth Neel , Aaron Roth

Motivated by the principle of satisficing in decision-making, we study satisficing regret guarantees for nonstationary $K$-armed bandits. We show that in the general realizable, piecewise-stationary setting with $L$ stationary segments, the…

Machine Learning · Statistics 2026-04-28 Yixuan Zhang , Ruihao Zhu , Qiaomin Xie

Generalized linear bandits have been extensively studied due to their broad applicability in real-world online decision-making problems. However, these methods typically assume that the expected reward function is known to the users, an…

Machine Learning · Statistics 2026-02-10 Yue Kang , Mingshuo Liu , Bongsoo Yi , Jing Lyu , Zhi Zhang , Doudou Zhou , Yao Li

This paper is in the field of stochastic Multi-Armed Bandits (MABs), i.e. those sequential selection techniques able to learn online using only the feedback given by the chosen option (a.k.a. $arm$). We study a particular case of the rested…

Machine Learning · Statistics 2024-11-28 Marco Fiandri , Alberto Maria Metelli , Francesco Trov`o