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Online Bilevel Optimization: Regret Analysis of Online Alternating Gradient Methods
Proceedings of The 27th International Conference on Artificial Intelligence and Statistics, PMLR 238:2854-2862, 2024.
Abstract
This paper introduces \textit{online bilevel optimization} in which a sequence of time-varying bilevel problems is revealed one after the other. We extend the known regret bounds for single-level online algorithms to the bilevel setting. Specifically, we provide new notions of \textit{bilevel regret}, develop an online alternating time-averaged gradient method that is capable of leveraging smoothness, and give regret bounds in terms of the path-length of the inner and outer minimizer sequences.