Handling Empty Decomposition Methods in Hierarchical Planning





hierarchical planning, empty methods, planning, HTN, hierarchical task networks


Hierarchical planning is a form of planning where tasks decompose into sub-tasks until primitive tasks (actions) are obtained. These decompositions might contain additional constraints, such as subtask ordering and state constraints. If a task is already fulfilled, it does not need to decompose into anything, but it may still require satisfaction of a particular state constraint (to check that the task is fulfilled). Such decomposition methods are called empty. Despite practical usefulness, many hierarchical planning models do not support empty methods fully. This paper shows that two recently introduced hierarchical planning formalisms are equivalent with respect to empty methods. We also discuss the possibility of compiling such methods away. In particular, we show how to compile them away in totally ordered domains and discuss the difficulties in partially ordered domains.




How to Cite

Ondrčková, S., Pantůčková, K., & Barták, R. (2024). Handling Empty Decomposition Methods in Hierarchical Planning. The International FLAIRS Conference Proceedings, 37(1). https://doi.org/10.32473/flairs.37.1.135304