The Dimensions of Driverlog

The International Planning Competition has provided a means of comparing the performance of planners. It is supposed to be a driving-force for planning technology. As the competition has advanced, more and more complex domains have been introduced. However, the methods for generating the competition instances are typically simplistic. At best, this means that our planners are not tested on the broad range of problem structures that can be expressed in each of the domains. At worst, it means that some search techniques (such as symmetry-breaking and graph-abstraction) are ineffective for the competition instances. It is our opinion that a competition with interesting instances (those with varied structural properties) would better drive the community to developing techniques that address real-world issues, and not just solving contrived competition test-cases. Towards this end, we present a preliminary problem generator for the Driverlog domain, and introduce several important qualities (or dimensions) of the domain. The performance of three planners on instances generated by our generator are compared with their performance on the competition instances.