Totally and Partially Ordered Hierarchical Planners in PDDL4J Library
  In this paper, we outline the implementation of the TFD (Totally Ordered Fast
Downward) and the PFD (Partially ordered Fast Downward) hierarchical planners
that participated in the first HTN IPC competition in 2020. These two planners
are based on forward-chaining task decomposition coupled with a compact
grounding of actions, methods, tasks and HTN problems.
