Title
Statistically Robust, Risk-Averse Best Arm Identification in Multi-Armed Bandits
Abstract
Traditional multi-armed bandit (MAB) formulations usually make certain assumptions about the underlying arms’ distributions, such as bounds on the support or their tail behaviour. Moreover, such parametric information is usually ‘baked’ into the algorithms. In this paper, we show that specialized algorithms that exploit such parametric information are prone to inconsistent learning performance when the parameter is misspecified. Our key contributions are twofold: (i) We establish fundamental performance limits of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">statistically robust</i> MAB algorithms under the fixed-budget pure exploration setting, and (ii) We propose two classes of algorithms that are asymptotically near-optimal. Additionally, we consider a risk-aware criterion for best arm identification, where the objective associated with each arm is a linear combination of the mean and the conditional value at risk (CVaR). Throughout, we make a very mild ‘bounded moment’ assumption, which lets us work with both light-tailed and heavy-tailed distributions within a unified framework.
Year
DOI
Venue
2022
10.1109/TIT.2022.3163524
IEEE Transactions on Information Theory
Keywords
DocType
Volume
Multi-armed bandits,best arm identification,conditional value-at-risk,concentration inequalities,robust statistics
Journal
68
Issue
ISSN
Citations 
8
0018-9448
0
PageRank 
References 
Authors
0.34
11
3
Name
Order
Citations
PageRank
Kagrecha, Anmol101.35
Jayakrishnan Nair27220.59
Krishna Jagannathan332.76