A Hierarchical Two-tier Approach to Hyper-parameter Optimization in Reinforcement Learning
This work addresses the problem of automating hyper-parameter tuning for reinforcement learning users, but it is incremental as it builds on existing Bayesian optimization methods.
The paper tackles hyper-parameter optimization in reinforcement learning by proposing a hierarchical two-tier approach using Bayesian optimization, validated in a simulated control task with promising results.
Optimization of hyper-parameters in reinforcement learning (RL) algorithms is a key task, because they determine how the agent will learn its policy by interacting with its environment, and thus what data is gathered. In this work, an approach that uses Bayesian optimization to perform a two-step optimization is proposed: first, categorical RL structure hyper-parameters are taken as binary variables and optimized with an acquisition function tailored for such variables. Then, at a lower level of abstraction, solution-level hyper-parameters are optimized by resorting to the expected improvement acquisition function, while using the best categorical hyper-parameters found in the optimization at the upper-level of abstraction. This two-tier approach is validated in a simulated control task. Results obtained are promising and open the way for more user-independent applications of reinforcement learning.