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Ordered Landmarks in Planning

Hoffmann, J. and Porteous, J. and Sebastia, L. (2004) Ordered Landmarks in Planning. Journal of Artificial Intelligence Research, 22. pp. 215-278.

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Abstract

Many known planning tasks have inherent constraints concerning the best order in which to achieve the goals. A number of research efforts have been made to detect such constraints and to use them for guiding search, in the hope of speeding up the planning process. We go beyond the previous approaches by considering ordering constraints not only over the (top-level) goals, but also over the sub-goals that will necessarily arise during planning. Landmarks are facts that must be true at some point in every valid solution plan. We extend Koehler and Hoffmann's definition of reasonable orders between top level goals to the more general case of landmarks. We show how landmarks can be found, how their reasonable orders can be approximated, and how this information can be used to decompose a given planning task into several smaller sub-tasks. Our methodology is completely domain- and planner-independent. The implementation demonstrates that the approach can yield significant runtime performance improvements when used as a control loop around state-of-the-art sub-optimal planning systems, as exemplified by FF and LPG.

Item type: Article
ID code: 1873
Keywords: Electronic computers. Computer science, Artificial Intelligence
Subjects: Science > Mathematics > Electronic computers. Computer science
Department: Faculty of Science > Computer and Information Sciences
Depositing user: Strathprints Administrator
Date Deposited: 05 Oct 2006
Last modified: 18 Jun 2015 03:57
URI: http://strathprints.strath.ac.uk/id/eprint/1873

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