Stochastic Zeroth-Order Optimization under Strongly Convexity and Lipschitz Hessian: Minimax Sample Complexity

Fuente: arXiv
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Autori principali: Yu, Qian, Wang, Yining, Huang, Baihe, Lei, Qi, Lee, Jason D.
Natura: Preprint
Pubblicazione: 2024
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author Yu, Qian
Wang, Yining
Huang, Baihe
Lei, Qi
Lee, Jason D.
author_facet Yu, Qian
Wang, Yining
Huang, Baihe
Lei, Qi
Lee, Jason D.
contents Optimization of convex functions under stochastic zeroth-order feedback has been a major and challenging question in online learning. In this work, we consider the problem of optimizing second-order smooth and strongly convex functions where the algorithm is only accessible to noisy evaluations of the objective function it queries. We provide the first tight characterization for the rate of the minimax simple regret by developing matching upper and lower bounds. We propose an algorithm that features a combination of a bootstrapping stage and a mirror-descent stage. Our main technical innovation consists of a sharp characterization for the spherical-sampling gradient estimator under higher-order smoothness conditions, which allows the algorithm to optimally balance the bias-variance tradeoff, and a new iterative method for the bootstrapping stage, which maintains the performance for unbounded Hessian.
format Preprint
id arxiv_https___arxiv_org_abs_2406_19617
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Stochastic Zeroth-Order Optimization under Strongly Convexity and Lipschitz Hessian: Minimax Sample Complexity
Yu, Qian
Wang, Yining
Huang, Baihe
Lei, Qi
Lee, Jason D.
Machine Learning
Information Theory
Optimization and Control
Optimization of convex functions under stochastic zeroth-order feedback has been a major and challenging question in online learning. In this work, we consider the problem of optimizing second-order smooth and strongly convex functions where the algorithm is only accessible to noisy evaluations of the objective function it queries. We provide the first tight characterization for the rate of the minimax simple regret by developing matching upper and lower bounds. We propose an algorithm that features a combination of a bootstrapping stage and a mirror-descent stage. Our main technical innovation consists of a sharp characterization for the spherical-sampling gradient estimator under higher-order smoothness conditions, which allows the algorithm to optimally balance the bias-variance tradeoff, and a new iterative method for the bootstrapping stage, which maintains the performance for unbounded Hessian.
title Stochastic Zeroth-Order Optimization under Strongly Convexity and Lipschitz Hessian: Minimax Sample Complexity
topic Machine Learning
Information Theory
Optimization and Control
url https://arxiv.org/abs/2406.19617