2021/05/24 by Wang, Kun, Dong, Jing, Wang, Baoxiang +2
#FOS: Computer and information sciences #Machine Learning (cs.LG)
paper · doi:10.48550/arxiv.2105.11126
This paper studies differential privacy (DP) and local differential privacy (LDP) in cascading bandits. Under DP, we propose an algorithm which guarantees ε-indistinguishability and a regret of O((\fraclog Tε)1+ξ) for an arbitrarily small ξ. This is a significant improvement from the previous work of O(\fraclog3 Tε) regret. Under (ε,δ)-LDP, we relax the K2 dependence through the tradeoff between privacy budget ε and error probability δ, and obtain a regret of O((Klog (1/δ) log T)/(ε2)), where K is the size of the arm subset. This result holds for both Gaussian mechanism and Laplace mechanism by analyses on the composition. Our results extend to combinatorial semi-bandit. We show respective lower bounds for DP and LDP cascading bandits. Extensive experiments corroborate our theoretic findings.