No-regret optimization of time-varying bilevel problems

Fuente: arXiv
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Main Authors: Mauduit, Eliabelle, Berthier, Eloïse, Simonetto, Andrea
Format: Preprint
Published: 2026
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author Mauduit, Eliabelle
Berthier, Eloïse
Simonetto, Andrea
author_facet Mauduit, Eliabelle
Berthier, Eloïse
Simonetto, Andrea
contents Bilevel optimization problems arise in many applications where decisions must account for the optimal response of another system, such as in game-theoretic settings. However, these problems are notoriously challenging, as even linear bilevel programs are strongly NP-hard. In this work, we consider bilevel optimization with a known upper-level objective and an unknown, potentially time-varying lower-level response, accessible only through noisy zeroth-order observations. We propose W-SparQ-BL, a Bayesian optimization framework that models the lower-level mapping using multi-output Gaussian processes and enables efficient optimization under uncertainty. Our approach leverages a sparse, observation-based approximation to control the effect of noise and temporal variability, while requiring only limited access to additional information over time. We establish regularity results linking the lower-level response to standard RKHS assumptions for common kernels, including Matérn and squared exponential. We prove that W-SparQ-BL achieves sublinear dynamic regret in both stationary and time-varying settings. Experiments on representative time-varying game-theoretic problems demonstrate the effectiveness of our approach.
format Preprint
id arxiv_https___arxiv_org_abs_2605_20962
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle No-regret optimization of time-varying bilevel problems
Mauduit, Eliabelle
Berthier, Eloïse
Simonetto, Andrea
Optimization and Control
Bilevel optimization problems arise in many applications where decisions must account for the optimal response of another system, such as in game-theoretic settings. However, these problems are notoriously challenging, as even linear bilevel programs are strongly NP-hard. In this work, we consider bilevel optimization with a known upper-level objective and an unknown, potentially time-varying lower-level response, accessible only through noisy zeroth-order observations. We propose W-SparQ-BL, a Bayesian optimization framework that models the lower-level mapping using multi-output Gaussian processes and enables efficient optimization under uncertainty. Our approach leverages a sparse, observation-based approximation to control the effect of noise and temporal variability, while requiring only limited access to additional information over time. We establish regularity results linking the lower-level response to standard RKHS assumptions for common kernels, including Matérn and squared exponential. We prove that W-SparQ-BL achieves sublinear dynamic regret in both stationary and time-varying settings. Experiments on representative time-varying game-theoretic problems demonstrate the effectiveness of our approach.
title No-regret optimization of time-varying bilevel problems
topic Optimization and Control
url https://arxiv.org/abs/2605.20962