Expressive Value Learning for Scalable Offline Reinforcement Learning
This work addresses scalability issues in offline RL for robotics and other domains, offering a method that avoids common bottlenecks, though it appears incremental as it builds on existing expressive models.
The paper tackles the scalability challenge in offline reinforcement learning by introducing EVOR, which integrates expressive policies and value functions to avoid computationally prohibitive methods like backpropagation through time or policy distillation, and it outperforms baselines on diverse offline RL tasks.
Reinforcement learning (RL) is a powerful paradigm for learning to make sequences of decisions. However, RL has yet to be fully leveraged in robotics, principally due to its lack of scalability. Offline RL offers a promising avenue by training agents on large, diverse datasets, avoiding the costly real-world interactions of online RL. Scaling offline RL to increasingly complex datasets requires expressive generative models such as diffusion and flow matching. However, existing methods typically depend on either backpropagation through time (BPTT), which is computationally prohibitive, or policy distillation, which introduces compounding errors and limits scalability to larger base policies. In this paper, we consider the question of how to develop a scalable offline RL approach without relying on distillation or backpropagation through time. We introduce Expressive Value Learning for Offline Reinforcement Learning (EVOR): a scalable offline RL approach that integrates both expressive policies and expressive value functions. EVOR learns an optimal, regularized Q-function via flow matching during training. At inference-time, EVOR performs inference-time policy extraction via rejection sampling against the expressive value function, enabling efficient optimization, regularization, and compute-scalable search without retraining. Empirically, we show that EVOR outperforms baselines on a diverse set of offline RL tasks, demonstrating the benefit of integrating expressive value learning into offline RL.