Gradient-free stochastic optimization for additive models

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Hauptverfasser: Akhavan, Arya, Tsybakov, Alexandre B.
Format: Preprint
Veröffentlicht: 2025
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author Akhavan, Arya
Tsybakov, Alexandre B.
author_facet Akhavan, Arya
Tsybakov, Alexandre B.
contents We address the problem of zero-order optimization from noisy observations for an objective function satisfying the Polyak-Łojasiewicz or the strong convexity condition. Additionally, we assume that the objective function has an additive structure and satisfies a higher-order smoothness property, characterized by the Hölder family of functions. The additive model for Hölder classes of functions is well-studied in the literature on nonparametric function estimation, where it is shown that such a model benefits from a substantial improvement of the estimation accuracy compared to the Hölder model without additive structure. We study this established framework in the context of gradient-free optimization. We propose a randomized gradient estimator that, when plugged into a gradient descent algorithm, allows one to achieve minimax optimal optimization error of the order $dT^{-(β-1)/β}$, where $d$ is the dimension of the problem, $T$ is the number of queries and $β\ge 2$ is the Hölder degree of smoothness. We conclude that, in contrast to nonparametric estimation problems, no substantial gain of accuracy can be achieved when using additive models in gradient-free optimization.
format Preprint
id arxiv_https___arxiv_org_abs_2503_02131
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Gradient-free stochastic optimization for additive models
Akhavan, Arya
Tsybakov, Alexandre B.
Machine Learning
We address the problem of zero-order optimization from noisy observations for an objective function satisfying the Polyak-Łojasiewicz or the strong convexity condition. Additionally, we assume that the objective function has an additive structure and satisfies a higher-order smoothness property, characterized by the Hölder family of functions. The additive model for Hölder classes of functions is well-studied in the literature on nonparametric function estimation, where it is shown that such a model benefits from a substantial improvement of the estimation accuracy compared to the Hölder model without additive structure. We study this established framework in the context of gradient-free optimization. We propose a randomized gradient estimator that, when plugged into a gradient descent algorithm, allows one to achieve minimax optimal optimization error of the order $dT^{-(β-1)/β}$, where $d$ is the dimension of the problem, $T$ is the number of queries and $β\ge 2$ is the Hölder degree of smoothness. We conclude that, in contrast to nonparametric estimation problems, no substantial gain of accuracy can be achieved when using additive models in gradient-free optimization.
title Gradient-free stochastic optimization for additive models
topic Machine Learning
url https://arxiv.org/abs/2503.02131