Neurosymbolic Reinforcement Learning with Formally Verified Exploration

Understand

We present Revel, a partially neural reinforcement learning (RL) framework for provably safe exploration in continuous state and action spaces.

• A key challenge for provably safe deep RL is that repeatedly verifying neural networks within a learning loop is computationally infeasible.
• We address this challenge using two policy classes: a general, neurosymbolic class with approximate gradients and a more restricted class of symbolic policies that allows efficient verification.
• Our learning algorithm is a mirror descent over policies: in each iteration, it safely lifts a symbolic policy into the neurosymbolic space, performs safe gradient updates to the resulting policy, and projects the updated policy into the safe symbolic subset, all without requiring explicit verification of neural networks.