We ran the planners in four 8-puzzle
problems and in two 15-puzzle ones, taken by Bonet and Geffner (2001). Two of
the four 8-puzzle are hard and their optimal solution involves 31 actions, the
maximum plan length in this domain. The 15-puzzle problems are of medium difficulty.
Figure 22 presents the results.
Figure 22: Solution length and time (msecs) in
the puzzle domain.
Stan solved only
the 8-puzzle instances, but it produced the best plans. The other planners
solved all the problems, but they presented variations in the quality of their
plans, with the Ff planning
system producing worst plans in most of the cases. Regarding solution time, Ff was the fastest in the easier
problems and Grt in the more
difficult ones, followed by Hsp-2
and Altalt. Stan was the slowest planner in this
domain.
Ioannis
Refanidis
14-8-2001