Temporal Planning With Required Concurrency Using Classical Planning

In this paper we describe two novel algorithms for temporal planning. The first algorithm, TP, is an adaptation of the TEMPO algorithm. It compiles each temporal action into two classical actions, corresponding to the start and end of the temporal action, but handles the temporal constraints on actions through a modification of the Fast Downward planning system. The second algorithm, TPSHE, is a pure compilation from temporal to classical planning for the case in which required concurrency only appears in the form of single hard envelopes. We describe novel classes of temporal planning instances for which TPSHE is provably sound and complete. Compiling a temporal instance into a classical one gives a lot of freedom in terms of the planner or heuristic used to solve the instance. In experiments TPSHE significantly outperforms all planners from the temporal track of the International Planning Competition.