Title
Lipschitz Bandits: Regret Lower Bounds and Optimal Algorithms.
Abstract
We consider stochastic multi-armed bandit problems where the expected reward is a Lipschitz function of the arm, and where the set of arms is either discrete or continuous. For discrete Lipschitz bandits, we derive asymptotic problem specific lower bounds for the regret satisfied by any algorithm, and propose OSLB and CKL-UCB, two algorithms that efficiently exploit the Lipschitz structure of the problem. In fact, we prove that OSLB is asymptotically optimal, as its asymptotic regret matches the lower bound. The regret analysis of our algorithms relies on a new concentration inequality for weighted sums of KL divergences between the empirical distributions of rewards and their true distributions. For continuous Lipschitz bandits, we propose to first discretize the action space, and then apply OSLB or CKL-UCB, algorithms that provably exploit the structure efficiently. This approach is shown, through numerical experiments, to significantly outperform existing algorithms that directly deal with the continuous set of arms. Finally the results and algorithms are extended to contextual bandits with similarities.
Year
Venue
Keywords
2014
COLT
computer science
DocType
Volume
Citations 
Journal
abs/1405.4758
15
PageRank 
References 
Authors
0.79
10
3
Name
Order
Citations
PageRank
Stefan Magureanu1292.82
Richard Combes2211.72
Alexandre Proutiere355840.94