Decoupling Exploration and Policy Optimization: Uncertainty Guided Tree Search for Hard Exploration
Zak Mhammedi, Google Reasearch
The process of discovery requires active exploration—the act of collecting new and informative data. However, efficient autonomous exploration remains a major unsolved problem. The dominant paradigm addresses this challenge by using Reinforcement Learning (RL) to train agents with intrinsic motivation, maximizing a composite objective of extrinsic and intrinsic rewards. We suggest that this approach incurs unnecessary overhead: while policy optimization is necessary for precise task execution, employing such machinery solely to expand state coverage may be inefficient.
In this talk, we propose a new paradigm that explicitly separates exploration from exploitation and bypasses RL during the exploration phase. Our method uses a tree-search strategy inspired by the Go-With-The-Winner algorithm, paired with a measure of epistemic uncertainty to systematically drive exploration. By removing the overhead of policy optimization, our approach explores an order of magnitude more efficiently than standard intrinsic motivation baselines on hard Atari benchmarks. Further, we will demonstrate that this unsupervised exploration mechanism generates high cumulative reward trajectories that can successfully be distilled into robust executable policies using existing supervised backward learning algorithms.