A Provably Convergent Plug-and-Play Framework for Stochastic Bilevel Optimization

Fuente: arXiv
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Autori principali: Chu, Tianshu, Xu, Dachuan, Yao, Wei, Yu, Chengming, Zhang, Jin
Natura: Preprint
Pubblicazione: 2025
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author Chu, Tianshu
Xu, Dachuan
Yao, Wei
Yu, Chengming
Zhang, Jin
author_facet Chu, Tianshu
Xu, Dachuan
Yao, Wei
Yu, Chengming
Zhang, Jin
contents Bilevel optimization has recently attracted significant attention in machine learning due to its wide range of applications and advanced hierarchical optimization capabilities. In this paper, we propose a plug-and-play framework, named PnPBO, for developing and analyzing stochastic bilevel optimization methods. This framework integrates both modern unbiased and biased stochastic estimators into the single-loop bilevel optimization framework introduced in [9], with several improvements. In the implementation of PnPBO, all stochastic estimators for different variables can be independently incorporated, and an additional moving average technique is applied when using an unbiased estimator for the upper-level variable. In the theoretical analysis, we provide a unified convergence and complexity analysis for PnPBO, demonstrating that the adaptation of various stochastic estimators (including PAGE, ZeroSARAH, and mixed strategies) within the PnPBO framework achieves optimal sample complexity, comparable to that of single-level optimization. This resolves the open question of whether the optimal complexity bounds for solving bilevel optimization are identical to those for single-level optimization. Finally, we empirically validate our framework, demonstrating its effectiveness on several benchmark problems and confirming our theoretical findings.
format Preprint
id arxiv_https___arxiv_org_abs_2505_01258
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle A Provably Convergent Plug-and-Play Framework for Stochastic Bilevel Optimization
Chu, Tianshu
Xu, Dachuan
Yao, Wei
Yu, Chengming
Zhang, Jin
Optimization and Control
Machine Learning
Bilevel optimization has recently attracted significant attention in machine learning due to its wide range of applications and advanced hierarchical optimization capabilities. In this paper, we propose a plug-and-play framework, named PnPBO, for developing and analyzing stochastic bilevel optimization methods. This framework integrates both modern unbiased and biased stochastic estimators into the single-loop bilevel optimization framework introduced in [9], with several improvements. In the implementation of PnPBO, all stochastic estimators for different variables can be independently incorporated, and an additional moving average technique is applied when using an unbiased estimator for the upper-level variable. In the theoretical analysis, we provide a unified convergence and complexity analysis for PnPBO, demonstrating that the adaptation of various stochastic estimators (including PAGE, ZeroSARAH, and mixed strategies) within the PnPBO framework achieves optimal sample complexity, comparable to that of single-level optimization. This resolves the open question of whether the optimal complexity bounds for solving bilevel optimization are identical to those for single-level optimization. Finally, we empirically validate our framework, demonstrating its effectiveness on several benchmark problems and confirming our theoretical findings.
title A Provably Convergent Plug-and-Play Framework for Stochastic Bilevel Optimization
topic Optimization and Control
Machine Learning
url https://arxiv.org/abs/2505.01258