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Hauptverfasser: Nie, Hantao, Li, Jiaxiang, Wen, Zaiwen
Format: Preprint
Veröffentlicht: 2025
Schlagworte:
Online-Zugang:https://arxiv.org/abs/2509.24249
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author Nie, Hantao
Li, Jiaxiang
Wen, Zaiwen
author_facet Nie, Hantao
Li, Jiaxiang
Wen, Zaiwen
contents Recently, lower-level constrained bilevel optimization has attracted increasing attention. However, existing methods mostly focus on either deterministic cases or problems with linear constraints. The main challenge in stochastic cases with general constraints is the bias and variance of the hyper-gradient, arising from the inexact solution of the lower-level problem. In this paper, we propose a novel stochastic augmented Lagrangian value function method for solving stochastic bilevel optimization problems with nonlinear lower-level constraints. Our approach reformulates the original bilevel problem using an augmented Lagrangian-based value function and then applies a penalized stochastic gradient method that carefully manages the noise from stochastic oracles. We establish an equivalence between the stochastic single-level reformulation and the original constrained bilevel problem and provide a non-asymptotic rate of convergence for the proposed method. The rate is further enhanced by employing variance reduction techniques. Extensive experiments on synthetic problems and real-world applications demonstrate the effectiveness of our approach.
format Preprint
id arxiv_https___arxiv_org_abs_2509_24249
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle An Augmented Lagrangian Value Function Method for Lower-level Constrained Stochastic Bilevel Optimization
Nie, Hantao
Li, Jiaxiang
Wen, Zaiwen
Optimization and Control
Recently, lower-level constrained bilevel optimization has attracted increasing attention. However, existing methods mostly focus on either deterministic cases or problems with linear constraints. The main challenge in stochastic cases with general constraints is the bias and variance of the hyper-gradient, arising from the inexact solution of the lower-level problem. In this paper, we propose a novel stochastic augmented Lagrangian value function method for solving stochastic bilevel optimization problems with nonlinear lower-level constraints. Our approach reformulates the original bilevel problem using an augmented Lagrangian-based value function and then applies a penalized stochastic gradient method that carefully manages the noise from stochastic oracles. We establish an equivalence between the stochastic single-level reformulation and the original constrained bilevel problem and provide a non-asymptotic rate of convergence for the proposed method. The rate is further enhanced by employing variance reduction techniques. Extensive experiments on synthetic problems and real-world applications demonstrate the effectiveness of our approach.
title An Augmented Lagrangian Value Function Method for Lower-level Constrained Stochastic Bilevel Optimization
topic Optimization and Control
url https://arxiv.org/abs/2509.24249