We study the problem of modeling spatiotemporal trajectories over long time
horizons using expert demonstrations. For instance, in sports, agents often
choose action sequences with long-term goals in mind, such as achieving a
certain strategic position. Conventional policy learning approaches, such as
those based on Markov decision processes, generally fail at learning cohesive
long-term behavior in such high-dimensional state spaces, and are only
effective when myopic modeling lead to the desired behavior. The key difficulty
is that conventional approaches are "shallow" models that only learn a single
state-action policy. We instead propose a hierarchical policy class that
automatically reasons about both long-term and short-term goals, which we
instantiate as a hierarchical neural network. We showcase our approach in a
case study on learning to imitate demonstrated basketball trajectories, and
show that it generates significantly more realistic trajectories compared to
non-hierarchical baselines as judged by professional sports analysts.

本文利用专家示范解决关于建模长时间轨迹的问题，通过提出一种层次化神经网络结构，能够在高维状态空间中，自动识别长短期目标，进而实现不同于传统方法由单一策略为核心，解决了传统方法在涉及长期行为建模上的局限。作者以模拟篮球运动轨迹的案例为例，通过专业体育分析师的判断得出，相较传统基准方法，作者提出的层次化策略能够生成更为真实的轨迹。