Randomized Greedy Algorithms for Neural Network Optimization

Fuente: arXiv
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Autori principali: Xu, Jinchao, Xu, Xiaofeng
Natura: Preprint
Pubblicazione: 2024
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author Xu, Jinchao
Xu, Xiaofeng
author_facet Xu, Jinchao
Xu, Xiaofeng
contents Greedy algorithms have been successfully analyzed and applied in training neural networks for solving variational problems, ensuring guaranteed convergence orders. In this paper, we extend the analysis of the orthogonal greedy algorithm (OGA) to convex optimization problems, establishing its optimal convergence rate. This result broadens the applicability of OGA by generalizing its optimal convergence rate from function approximation to convex optimization problems. In addition, we also address the issue regarding practical applicability of greedy algorithms, which is due to significant computational costs from the subproblems that involve an exhaustive search over a discrete dictionary. We propose to use a more practical approach of randomly discretizing the dictionary at each iteration of the greedy algorithm. We quantify the required size of the randomized discrete dictionary and prove that, with high probability, the proposed algorithm realizes a weak greedy algorithm, achieving optimal convergence orders. Through numerous numerical experiments on function approximation, linear and nonlinear elliptic partial differential equations, we validate our analysis on the optimal convergence rate and demonstrate the advantage of using randomized discrete dictionaries over a deterministic one by showing orders of magnitude reductions in the size of the discrete dictionary, particularly in higher dimensions.
format Preprint
id arxiv_https___arxiv_org_abs_2407_17763
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Randomized Greedy Algorithms for Neural Network Optimization
Xu, Jinchao
Xu, Xiaofeng
Numerical Analysis
65D15, 65N12, 65N75, 41A25
Greedy algorithms have been successfully analyzed and applied in training neural networks for solving variational problems, ensuring guaranteed convergence orders. In this paper, we extend the analysis of the orthogonal greedy algorithm (OGA) to convex optimization problems, establishing its optimal convergence rate. This result broadens the applicability of OGA by generalizing its optimal convergence rate from function approximation to convex optimization problems. In addition, we also address the issue regarding practical applicability of greedy algorithms, which is due to significant computational costs from the subproblems that involve an exhaustive search over a discrete dictionary. We propose to use a more practical approach of randomly discretizing the dictionary at each iteration of the greedy algorithm. We quantify the required size of the randomized discrete dictionary and prove that, with high probability, the proposed algorithm realizes a weak greedy algorithm, achieving optimal convergence orders. Through numerous numerical experiments on function approximation, linear and nonlinear elliptic partial differential equations, we validate our analysis on the optimal convergence rate and demonstrate the advantage of using randomized discrete dictionaries over a deterministic one by showing orders of magnitude reductions in the size of the discrete dictionary, particularly in higher dimensions.
title Randomized Greedy Algorithms for Neural Network Optimization
topic Numerical Analysis
65D15, 65N12, 65N75, 41A25
url https://arxiv.org/abs/2407.17763