An Accelerated Gradient Method for Convex Smooth Simple Bilevel Optimization

Fuente: arXiv
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Main Authors: Cao, Jincheng, Jiang, Ruichen, Hamedani, Erfan Yazdandoost, Mokhtari, Aryan
Format: Preprint
Published: 2024
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author Cao, Jincheng
Jiang, Ruichen
Hamedani, Erfan Yazdandoost
Mokhtari, Aryan
author_facet Cao, Jincheng
Jiang, Ruichen
Hamedani, Erfan Yazdandoost
Mokhtari, Aryan
contents In this paper, we focus on simple bilevel optimization problems, where we minimize a convex smooth objective function over the optimal solution set of another convex smooth constrained optimization problem. We present a novel bilevel optimization method that locally approximates the solution set of the lower-level problem using a cutting plane approach and employs an accelerated gradient-based update to reduce the upper-level objective function over the approximated solution set. We measure the performance of our method in terms of suboptimality and infeasibility errors and provide non-asymptotic convergence guarantees for both error criteria. Specifically, when the feasible set is compact, we show that our method requires at most $\mathcal{O}(\max\{1/\sqrt{ε_{f}}, 1/ε_g\})$ iterations to find a solution that is $ε_f$-suboptimal and $ε_g$-infeasible. Moreover, under the additional assumption that the lower-level objective satisfies the $r$-th Hölderian error bound, we show that our method achieves an iteration complexity of $\mathcal{O}(\max\{ε_{f}^{-\frac{2r-1}{2r}},ε_{g}^{-\frac{2r-1}{2r}}\})$, which matches the optimal complexity of single-level convex constrained optimization when $r=1$.
format Preprint
id arxiv_https___arxiv_org_abs_2402_08097
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle An Accelerated Gradient Method for Convex Smooth Simple Bilevel Optimization
Cao, Jincheng
Jiang, Ruichen
Hamedani, Erfan Yazdandoost
Mokhtari, Aryan
Optimization and Control
Machine Learning
In this paper, we focus on simple bilevel optimization problems, where we minimize a convex smooth objective function over the optimal solution set of another convex smooth constrained optimization problem. We present a novel bilevel optimization method that locally approximates the solution set of the lower-level problem using a cutting plane approach and employs an accelerated gradient-based update to reduce the upper-level objective function over the approximated solution set. We measure the performance of our method in terms of suboptimality and infeasibility errors and provide non-asymptotic convergence guarantees for both error criteria. Specifically, when the feasible set is compact, we show that our method requires at most $\mathcal{O}(\max\{1/\sqrt{ε_{f}}, 1/ε_g\})$ iterations to find a solution that is $ε_f$-suboptimal and $ε_g$-infeasible. Moreover, under the additional assumption that the lower-level objective satisfies the $r$-th Hölderian error bound, we show that our method achieves an iteration complexity of $\mathcal{O}(\max\{ε_{f}^{-\frac{2r-1}{2r}},ε_{g}^{-\frac{2r-1}{2r}}\})$, which matches the optimal complexity of single-level convex constrained optimization when $r=1$.
title An Accelerated Gradient Method for Convex Smooth Simple Bilevel Optimization
topic Optimization and Control
Machine Learning
url https://arxiv.org/abs/2402.08097