Title
Model Selection in Contextual Stochastic Bandit Problems
Abstract
We study model selection in stochastic bandit problems. Our approach relies on a master algorithm that selects its actions among candidate base algorithms. While this problem is studied for specific classes of stochastic base algorithms, our objective is to provide a method that can work with more general classes of stochastic base algorithms. We propose a master algorithm inspired by CORRAL \cite{DBLP:conf/colt/AgarwalLNS17} and introduce a novel and generic smoothing transformation for stochastic bandit algorithms that permits us to obtain $O(\sqrt{T})$ regret guarantees for a wide class of base algorithms when working along with our master. We exhibit a lower bound showing that even when one of the base algorithms has $O(\log T)$ regret, in general it is impossible to get better than $\Omega(\sqrt{T})$ regret in model selection, even asymptotically. We apply our algorithm to choose among different values of $\epsilon$ for the $\epsilon$-greedy algorithm, and to choose between the $k$-armed UCB and linear UCB algorithms. Our empirical studies further confirm the effectiveness of our model-selection method.
Year
Venue
DocType
2020
NIPS 2020
Conference
Volume
Citations 
PageRank 
33
0
0.34
References 
Authors
0
7
Name
Order
Citations
PageRank
Aldo Pacchiano11011.62
My V. T. Phan281.83
Yasin Abbasi-Yadkori327323.80
Anup Rao458132.80
Julian Zimmert522.80
Tor Lattimore617429.15
Csaba Szepesvári71774157.06