Applying reinforcement learning (RL) to sparse reward domains is notoriously challenging due to insufficient guiding signals. Common techniques for addressing such domains include (1) learning from demonstrations and (2) curriculum learning. While these two approaches have been studied in detail, they have rarely been considered together. This paper aims to do so by introducing a principled task phasing approach that uses demonstrations to automatically generate a curriculum sequence. Using inverse RL from (suboptimal) demonstrations we define a simple initial task. Our task phasing approach then provides a framework to gradually increase the complexity of the task all the way to the target task, while retuning the RL agent in each phasing iteration. Two approaches for phasing are considered: (1) gradually increasing the proportion of time steps an RL agent is in control, and (2) phasing out a guiding informative reward function. We present conditions that guarantee the convergence of these approaches to an optimal policy. Experimental results on 3 sparse reward domains demonstrate that our task phasing approaches outperform state-of-the-art approaches with respect to their asymptotic performance.

本文介绍了一种基于任务分阶段的机器学习方法，通过逐步提高任务复杂度并调节反馈信息，针对稀疏奖励问题下的强化学习进行探索，并取得了较好成果。

任务分阶段：从示范中自动学习课程