2020

A Two-Timescale Framework for Bilevel Optimization: Complexity Analysis and Application to Actor-Critic

Hong, Mingyi, Wai, Hoi-To, Wang, Zhaoran et al.

Understand

This paper analyzes a two-timescale stochastic algorithm framework for bilevel optimization.

  • Bilevel optimization is a class of problems which exhibit a two-level structure, and its goal is to minimize an outer objective function with variables which are constrained to be the optimal solution to an (inner) optimization problem.
  • We consider the case when the inner problem is unconstrained and strongly convex, while the outer problem is constrained and has a smooth objective function.
  • We propose a two-timescale stochastic approximation (TTSA) algorithm for tackling such a bilevel problem.

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