VHPOP: Versatile Heuristic Partial Order Planner

Best Newcomer at the 3rd International Planning Competition.

VHPOP is a partial order causal link (POCL) planner loosely based on UCPOP. It draws from the experience gained in the early to mid 1990's on flaw selection strategies for POCL planning, and combines this with more recent developments in the field of domain independent planning such as distance based heuristics and reachability analysis. VHPOP also supports planning with durative actions by incorporating standard techniques for temporal constraint reasoning.

Read the anecdotal story about the development of the planner leading up the 3rd International Planning Competition.

Main features:

• Can plan with either ground or lifted actions.
• Can enforce joint parameter domain constraints when planning with lifted actions.
• Has several different plan ranking heuristics to choose from that can be combined into complex plan ranking functions.
• Efficiently implements all common flaw selection strategies, including LCFR and ZLIFO, and many novel ones, and allows flaw selection strategies to be specified using a concise notation.
• Several flaw selection strategies can be used simultaneously.
• Implements A*, IDA*, and hill climbing search.
• Fully supports levels 1 and 3 of PDDL+.

Released versions of VHPOP can be downloaded here.

The source code for VHPOP is hosted on GitHub.

Publications

• Håkan L. S. Younes and Reid G. Simmons. 2003. VHPOP: Versatile heuristic partial order planner. Journal of Artificial Intelligence Research 20: 405–430.

• Håkan L. S. Younes and Reid G. Simmons. 2002. On the role of ground actions in refinement planning. In Proceedings of the Sixth International Conference on Artificial Intelligence Planning and Scheduling Systems, edited by Malik Ghallab, Joachim Hertzberg, and Paolo Traverso, 54–61, Toulouse, France. AAAI Press.

Related Work

• RePOP
• UCPOP