A Surrogate Value Function Formulation for Bilevel Optimization

Fuente: arXiv
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Hauptverfasser: Xu, Mengwei, Dai, Yu-Hong, Liu, Xin-Wei, Ma, Meiqi
Format: Preprint
Veröffentlicht: 2025
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_version_ 1866915563179081728
author Xu, Mengwei
Dai, Yu-Hong
Liu, Xin-Wei
Ma, Meiqi
author_facet Xu, Mengwei
Dai, Yu-Hong
Liu, Xin-Wei
Ma, Meiqi
contents The value function formulation captures the hierarchical nature of bilevel optimization through the optimal value function of the lower level problem, yet its implicit and nonsmooth characteristics pose significant analytical and computational difficulties. We introduce a surrogate value function formulation that replaces the intractable value function with an explicit surrogate derived from lower level stationarity conditions. This surrogate formulation preserves the essential idea of the classical value function model but fundamentally departs from Karush Kuhn Tucker (KKT) formulations, which embed lower level stationary points into the upper level feasible region and obscure the hierarchical dependence. Instead, it enforces the hierarchy through a dominance constraint that remains valid even when lower level constraint qualifications fail at the solution. We establish equivalence with the original bilevel problem, reveal the failure of standard constraint qualifications, and show that its strong stationarity implies that of KKT models. To handle the complementarity constraints in the surrogate formulation, we apply a smoothing barrier augmented Lagrangian method and prove its convergence to solutions and Clarke stationary points. Extensive experiments demonstrate the robustness and high numerical precision of this formulation, especially in nonconvex settings, including the classical Mirrlees problem where KKT models fail.
format Preprint
id arxiv_https___arxiv_org_abs_2510_16818
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle A Surrogate Value Function Formulation for Bilevel Optimization
Xu, Mengwei
Dai, Yu-Hong
Liu, Xin-Wei
Ma, Meiqi
Optimization and Control
90C26, 90C30, 90C33
The value function formulation captures the hierarchical nature of bilevel optimization through the optimal value function of the lower level problem, yet its implicit and nonsmooth characteristics pose significant analytical and computational difficulties. We introduce a surrogate value function formulation that replaces the intractable value function with an explicit surrogate derived from lower level stationarity conditions. This surrogate formulation preserves the essential idea of the classical value function model but fundamentally departs from Karush Kuhn Tucker (KKT) formulations, which embed lower level stationary points into the upper level feasible region and obscure the hierarchical dependence. Instead, it enforces the hierarchy through a dominance constraint that remains valid even when lower level constraint qualifications fail at the solution. We establish equivalence with the original bilevel problem, reveal the failure of standard constraint qualifications, and show that its strong stationarity implies that of KKT models. To handle the complementarity constraints in the surrogate formulation, we apply a smoothing barrier augmented Lagrangian method and prove its convergence to solutions and Clarke stationary points. Extensive experiments demonstrate the robustness and high numerical precision of this formulation, especially in nonconvex settings, including the classical Mirrlees problem where KKT models fail.
title A Surrogate Value Function Formulation for Bilevel Optimization
topic Optimization and Control
90C26, 90C30, 90C33
url https://arxiv.org/abs/2510.16818