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We study the problem of corralling stochastic bandit algorithms, that is combining multiple bandit algorithms designed for a stochastic environment, with the goal of devising a corralling algorithm that performs almost as well as the best…

Machine Learning · Computer Science 2021-03-02 Raman Arora , Teodor V. Marinov , Mehryar Mohri

We consider offline policy optimization (OPO) in contextual bandits, where one is given a fixed dataset of logged interactions. While pessimistic regularizers are typically used to mitigate distribution shift, prior implementations thereof…

Machine Learning · Computer Science 2023-10-27 Lequn Wang , Akshay Krishnamurthy , Aleksandrs Slivkins

Multi-armed bandit models have proven to be useful in modeling many real world problems in the areas of control and sequential decision making with partial information. However, in many scenarios, such as those prevalent in healthcare and…

Optimization and Control · Mathematics 2024-08-27 Qinyang He , Yonatan Mintz

In decision-making problems such as the multi-armed bandit, an agent learns sequentially by optimizing a certain feedback. While the mean reward criterion has been extensively studied, other measures that reflect an aversion to adverse…

Machine Learning · Statistics 2023-03-28 Patrick Saux , Odalric-Ambrym Maillard

In several applications such as clinical trials and financial portfolio optimization, the expected value (or the average reward) does not satisfactorily capture the merits of a drug or a portfolio. In such applications, risk plays a crucial…

Machine Learning · Statistics 2022-05-13 Vincent Y. F. Tan , Prashanth L. A. , Krishna Jagannathan

Stochastic multi-armed bandits solve the Exploration-Exploitation dilemma and ultimately maximize the expected reward. Nonetheless, in many practical problems, maximizing the expected reward is not the most desirable objective. In this…

Machine Learning · Computer Science 2013-01-10 Amir Sani , Alessandro Lazaric , Rémi Munos

In this paper we study a multi-arm bandit problem in which the quality of each arm is measured by the Conditional Value at Risk (CVaR) at some level alpha of the reward distribution. While existing works in this setting mainly focus on…

Machine Learning · Computer Science 2022-03-22 Dorian Baudry , Romain Gautron , Emilie Kaufmann , Odalric-Ambryn Maillard

In a typical stochastic multi-armed bandit problem, the objective is often to maximize the expected sum of rewards over some time horizon $T$. While the choice of a strategy that accomplishes that is optimal with no additional information,…

Machine Learning · Computer Science 2023-11-01 Reda Alami , Mohammed Mahfoud , Mastane Achab

In this paper, we study the stochastic combinatorial multi-armed bandit problem under semi-bandit feedback. While much work has been done on algorithms that optimize the expected reward for linear as well as some general reward functions,…

Machine Learning · Computer Science 2021-12-03 Shaarad Ayyagari , Ambedkar Dukkipati

We study the bandit problem where the underlying expected reward is a Bounded Mean Oscillation (BMO) function. BMO functions are allowed to be discontinuous and unbounded, and are useful in modeling signals with infinities in the do-main.…

Machine Learning · Computer Science 2020-07-20 Tianyu Wang , Cynthia Rudin

We consider the problem of bandit optimization, inspired by stochastic optimization and online learning problems with bandit feedback. In this problem, the objective is to minimize a global loss function of all the actions, not necessarily…

Machine Learning · Computer Science 2017-09-07 Quentin Berthet , Vianney Perchet

Bayesian optimisation (BO) is widely used to optimise stochastic black box functions. While most BO approaches focus on optimising conditional expectations, many applications require risk-averse strategies and alternative criteria…

Machine Learning · Statistics 2022-07-11 Victor Picheny , Henry Moss , Léonard Torossian , Nicolas Durrande

We consider the problem of decision-making under uncertainty in an environment with safety constraints. Many business and industrial applications rely on real-time optimization to improve key performance indicators. In the case of unknown…

Machine Learning · Computer Science 2023-01-31 Buse Sibel Korkmaz , Marta Zagórowska , Mehmet Mercangöz

We consider a variant of the best arm identification task in stochastic multi-armed bandits. Motivated by risk-averse decision-making problems, our goal is to identify a set of $m$ arms with the highest $\tau$-quantile values within a fixed…

Machine Learning · Computer Science 2023-02-22 Mengyan Zhang , Cheng Soon Ong

Bandit convex optimization (BCO) is a general framework for online decision making under uncertainty. While tight regret bounds for general convex losses have been established, existing algorithms achieving these bounds have prohibitive…

Machine Learning · Computer Science 2024-10-04 Arun Suggala , Y. Jennifer Sun , Praneeth Netrapalli , Elad Hazan

Classical multi-armed bandit problems use the expected value of an arm as a metric to evaluate its goodness. However, the expected value is a risk-neutral metric. In many applications like finance, one is interested in balancing the…

Machine Learning · Computer Science 2019-06-04 Anmol Kagrecha , Jayakrishnan Nair , Krishna Jagannathan

We study reward maximisation in a wide class of structured stochastic multi-armed bandit problems, where the mean rewards of arms satisfy some given structural constraints, e.g. linear, unimodal, sparse, etc. Our aim is to develop methods…

Machine Learning · Statistics 2020-07-03 Rémy Degenne , Han Shao , Wouter M. Koolen

Many challenges in science and engineering, such as drug discovery and communication network design, involve optimizing complex and expensive black-box functions across vast search spaces. Thus, it is essential to leverage existing data to…

Machine Learning · Computer Science 2024-12-04 Juncheng Dong , Zihao Wu , Hamid Jafarkhani , Ali Pezeshki , Vahid Tarokh

We consider an online stochastic game with risk-averse agents whose goal is to learn optimal decisions that minimize the risk of incurring significantly high costs. Specifically, we use the Conditional Value at Risk (CVaR) as a risk measure…

Machine Learning · Computer Science 2022-06-17 Zifan Wang , Yi Shen , Michael M. Zavlanos

Best-of-both-worlds algorithms for online learning which achieve near-optimal regret in both the adversarial and the stochastic regimes have received growing attention recently. Existing techniques often require careful adaptation to every…

Machine Learning · Computer Science 2023-02-21 Christoph Dann , Chen-Yu Wei , Julian Zimmert