Offline reinforcement learning suffers from the out-of-distribution issue and extrapolation error. Most policy constraint methods regularize the density of the trained policy towards the behavior policy, which is too restrictive in most cases. We propose Supported Trust Region optimization (STR) which performs trust region policy optimization with the policy constrained within the support of the behavior policy, enjoying the less restrictive support constraint. We show that, when assuming no approximation and sampling error, STR guarantees strict policy improvement until convergence to the optimal support-constrained policy in the dataset. Further with both errors incorporated, STR still guarantees safe policy improvement for each step. Empirical results validate the theory of STR and demonstrate its state-of-the-art performance on MuJoCo locomotion domains and much more challenging AntMaze domains.

在离线强化学习中，基于行为策略的支持约束的支持下的支持信任区域优化（STR）保证了严格的策略改进，并在包括近似误差和采样误差的情况下保证步骤的安全策略改进，其理论和实证结果验证了其在MuJoCo运动领域和具有更具挑战性的AntMaze领域的卓越性能。

离线强化学习的支持信任域优化