Guest Editors

David E. Smith

Special Track Contents

The International Planning Competition Series began in 1998 and has been running biennially since that date. The competitions have been an important driver for research in the field. In particular, they have resulted in an evolving language for describing planning domains and problems (PDDL), a body of benchmark domains and problems in that language, and the ability to directly compare different generative planning techniques. All of this has contributed to significant advances in both the character and difficulty of problems that can be represented and solved by generative planning techniques.

The papers in this JAIR Special Issue cover the 3rd International Planning Competition (IPC-3), held in conjunction with the 6th International Conference on AI Planning and Scheduling (AIPS-02). This competition marks the introduction of planning problems and systems that deal explicitly with time and numeric quantities. The first paper (Long & Fox) describes the results of the competition. The second paper (Fox & Long) presents the language extensions to PDDL that allow it to express numeric quantities, metric optimization criteria, and actions having duration. Because the language extensions were controversial, the paper is followed by a collection of short commentaries by prominent members of the field. The remaining papers describe the techniques and systems that figured prominently in the competition.