Exploiting Action Impact Regularity and Partially Known Models for Offline Reinforcement Learning

Offline reinforcement learning-learning a policy from a batch of data-is known to be hard: without making strong assumptions, it is easy to construct counterexamples such that existing algorithms fail. In this work, we instead consider a property of certain real world problems where offline reinforcement learning should be effective: those where actions only have limited impact for a part of the state. We formalize and introduce this Action Impact Regularity (AIR) property. We further propose an algorithm that assumes and exploits the AIR property, and bound the suboptimality of the output policy when the MDP satisfies AIR. Finally, we demonstrate that our algorithm outperforms existing offline reinforcement learning algorithms across different data collection policies in two simulated environments where the regularity holds.