Title
A Single-Timescale Method for Stochastic Bilevel Optimization
Abstract
Stochastic bilevel optimization generalizes the classic stochastic optimization from the minimization of a single objective to the minimization of an objective function that depends on the solution of another optimization problem. Recently, bilevel optimization is regaining popularity in emerging machine learning applications such as hyper-parameter optimization and model-agnostic meta learning. To solve this class of optimization problems, existing methods require either double-loop or two-timescale updates, which are sometimes less efficient. This paper develops a new optimization method for a class of stochastic bilevel problems that we term Single-Timescale stochAstic BiLevEl optimization (STABLE) method. STABLE runs in a single loop fashion, and uses a single-timescale update with a fixed batch size. To achieve an epsilon-stationary point of the bilevel problem, STABLE requires O (epsilon(-2)) samples in total; and to achieve an epsilon-optimal solution in the strongly convex case, STABLE requires O (epsilon(-1)) samples. To the best of our knowledge, when STABLE was proposed, it is the first bilevel optimization algorithm achieving the same order of sample complexity as SGD for single-level stochastic optimization.
Year
Venue
DocType
2022
INTERNATIONAL CONFERENCE ON ARTIFICIAL INTELLIGENCE AND STATISTICS, VOL 151
Conference
Volume
ISSN
Citations 
151
2640-3498
0
PageRank 
References 
Authors
0.34
0
4
Name
Order
Citations
PageRank
Tianyi Chen1437.52
Yuejiao Sun200.34
Quan Xiao300.68
Wotao Yin45038243.92