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Tight Regret Bounds for Bayesian Optimization in One Dimension
Proceedings of the 35th International Conference on Machine Learning, PMLR 80:4500-4508, 2018.
Abstract
We consider the problem of Bayesian optimization (BO) in one dimension, under a Gaussian process prior and Gaussian sampling noise. We provide a theoretical analysis showing that, under fairly mild technical assumptions on the kernel, the best possible cumulative regret up to time T behaves as Ω(√T) and O(√TlogT). This gives a tight characterization up to a √logT factor, and includes the first non-trivial lower bound for noisy BO. Our assumptions are satisfied, for example, by the squared exponential and Matérn-ν kernels, with the latter requiring ν>2. Our results certify the near-optimality of existing bounds (Srinivas et al., 2009) for the SE kernel, while proving them to be strictly suboptimal for the Matérn kernel with ν>2.