An Admissible HTN Planning Heuristic

Pascal Bercher, Gregor Behnke, Daniel Höller, Susanne Biundo
2017 Proceedings of the Twenty-Sixth International Joint Conference on Artificial Intelligence  
Hierarchical task network (HTN) planning is well-known for being an efficient planning approach. This is mainly due to the success of the HTN planning system SHOP2. However, its performance depends on hand-designed search control knowledge. At the time being, there are only very few domain-independent heuristics, which are designed for differing hierarchical planning formalisms. Here, we propose an admissible heuristic for standard HTN planning, which allows to find optimal solutions
more » ... ly. It bases upon the so-called task decomposition graph (TDG), a data structure reflecting reachable parts of the task hierarchy. We show (both in theory and empirically) that rebuilding it during planning can improve heuristic accuracy thereby decreasing the explored search space. The evaluation further studies the heuristic both in terms of plan quality and coverage.
doi:10.24963/ijcai.2017/68 dblp:conf/ijcai/BercherBHB17 fatcat:hnzgdtwwbnbellzhzmfaj5hzai