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A Parameter-Free and Near-Optimal Zeroth-Order Algorithm for Stochastic Convex Optimization
Proceedings of the 42nd International Conference on Machine Learning, PMLR 267:51450-51470, 2025.
Abstract
This paper studies zeroth-order optimization for stochastic convex minimization problems. We propose a parameter-free stochastic zeroth-order method (POEM), which introduces a step-size scheme based on the distance over finite difference and an adaptive smoothing parameter. Our theoretical analysis shows that POEM achieves near-optimal stochastic zeroth-order oracle complexity. Furthermore, numerical experiments demonstrate that POEM outperforms existing zeroth-order methods in practice.