Improving Policy Optimization via ε-Retrain

We present 𝐿-retrain, an exploration strategy encouraging a behavioral preference while optimizing policies with monotonic improvement guarantees. To this end, we introduce an iterative procedure for collecting retrain areas—parts of the state space where an agent did not satisfy the behavioral preference. Our method switches between the typical uniform restart state distribution and the retrain areas using a decaying factor 𝐿, allowing agents to retrain on situations where they violated the preference. We also employ formal veri! cation of neural networks to provably quantify the degree to which agents adhere to these behavioral preferences. Experiments over hundreds of seeds across locomotion, power network, and navigation tasks show that our method yields agents that exhibit signi! cant performance and sample e"ciency improvements.

Authors

• Luca Marzari University of Verona
• Priya L. Donti Massachusetts Institute of Technology
• Changliu Liu Carnegie Mellon University
• Enrico Marchesini Massachusetts Institute of Technology

Keywords

• Reinforcement learning
• policy gradient
• formal veri! cation