We study the problem of representation transfer in offline Reinforcement Learning (RL), where a learner has access to episodic data from a number of source tasks collected a priori, and aims to learn a shared representation to be used in finding a good policy for a target task. Unlike in online RL where the agent interacts with the environment while learning a policy, in the offline setting there cannot be such interactions in either the source tasks or the target task; thus multi-task offline RL can suffer from incomplete coverage. We propose an algorithm to compute pointwise uncertainty measures for the learnt representation, and establish a data-dependent upper bound for the suboptimality of the learnt policy for the target task. Our algorithm leverages the collective exploration done by source tasks to mitigate poor coverage at some points by a few tasks, thus overcoming the limitation of needing uniformly good coverage for a meaningful transfer by existing offline algorithms. We complement our theoretical results with empirical evaluation on a rich-observation MDP which requires many samples for complete coverage. Our findings illustrate the benefits of penalizing and quantifying the uncertainty in the learnt representation.

我们研究了离线强化学习中的表示转移问题，提出了一种算法来计算学习表示的点态不确定性度量，并通过扩展数据的数据依赖上界证明了针对目标任务的学习策略的次优性。我们的算法利用源任务的集体探索来解决现有离线算法在一些点上覆盖不足的问题，并在需要完全覆盖的富观测马尔可夫决策过程上进行了实证评估，展示了惩罚和量化学习表示中的不确定性的益处。

离线多任务转移强化学习与表示惩罚