First-Order Methods for Linearly Constrained Bilevel Optimization

Fuente: arXiv
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Main Authors: Kornowski, Guy, Padmanabhan, Swati, Wang, Kai, Zhang, Zhe, Sra, Suvrit
Format: Preprint
Published: 2024
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_version_ 1866915250420318208
author Kornowski, Guy
Padmanabhan, Swati
Wang, Kai
Zhang, Zhe
Sra, Suvrit
author_facet Kornowski, Guy
Padmanabhan, Swati
Wang, Kai
Zhang, Zhe
Sra, Suvrit
contents Algorithms for bilevel optimization often encounter Hessian computations, which are prohibitive in high dimensions. While recent works offer first-order methods for unconstrained bilevel problems, the constrained setting remains relatively underexplored. We present first-order linearly constrained optimization methods with finite-time hypergradient stationarity guarantees. For linear equality constraints, we attain $ε$-stationarity in $\widetilde{O}(ε^{-2})$ gradient oracle calls, which is nearly-optimal. For linear inequality constraints, we attain $(δ,ε)$-Goldstein stationarity in $\widetilde{O}(d{δ^{-1} ε^{-3}})$ gradient oracle calls, where $d$ is the upper-level dimension. Finally, we obtain for the linear inequality setting dimension-free rates of $\widetilde{O}({δ^{-1} ε^{-4}})$ oracle complexity under the additional assumption of oracle access to the optimal dual variable. Along the way, we develop new nonsmooth nonconvex optimization methods with inexact oracles. We verify these guarantees with preliminary numerical experiments.
format Preprint
id arxiv_https___arxiv_org_abs_2406_12771
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle First-Order Methods for Linearly Constrained Bilevel Optimization
Kornowski, Guy
Padmanabhan, Swati
Wang, Kai
Zhang, Zhe
Sra, Suvrit
Optimization and Control
Machine Learning
Algorithms for bilevel optimization often encounter Hessian computations, which are prohibitive in high dimensions. While recent works offer first-order methods for unconstrained bilevel problems, the constrained setting remains relatively underexplored. We present first-order linearly constrained optimization methods with finite-time hypergradient stationarity guarantees. For linear equality constraints, we attain $ε$-stationarity in $\widetilde{O}(ε^{-2})$ gradient oracle calls, which is nearly-optimal. For linear inequality constraints, we attain $(δ,ε)$-Goldstein stationarity in $\widetilde{O}(d{δ^{-1} ε^{-3}})$ gradient oracle calls, where $d$ is the upper-level dimension. Finally, we obtain for the linear inequality setting dimension-free rates of $\widetilde{O}({δ^{-1} ε^{-4}})$ oracle complexity under the additional assumption of oracle access to the optimal dual variable. Along the way, we develop new nonsmooth nonconvex optimization methods with inexact oracles. We verify these guarantees with preliminary numerical experiments.
title First-Order Methods for Linearly Constrained Bilevel Optimization
topic Optimization and Control
Machine Learning
url https://arxiv.org/abs/2406.12771