Alfonso Gerevini, Ivan Serina, Alessandro Saetti, and Sergio Spinoni
We present some techniques for planning in temporal domains specified with the recent standard languange PDDL2.1. These techniques are implemented in LPG, a fully-automated system that took part in the third International Planning Competition (Toulouse, 2002) showing excellent performance. The planner is based on a stochastic local search method and on a graph-based representation called "Temporal Action Graphs" (TA-graphs). In this paper we present some new heuristics to guide the search in LPG using this representation. An experimental analysis of the performance of LPG on a large set of test problems used in the competition shows that our techniques can be very effective, and that often our planner outperforms all other fully-automated temporal planners that took part in the contest.