Heuristic Search Planner 2.0

We describe the HSP2.0 planning algorithm that entered the Second Planning Contest held in AIPS2000. HSP2.0 is a domain independent planning algorithm that implements the family of heuristic search planners that are characterized by the state space that is searched (either progression or regression space), the search algorithm used, and the heuristic function that is used. This general planner implements a scheduler that tries different variants in parallel with different (time) resource bounds. We also describe how HSP2.0 can be used as an optimal (and near-optimal) planning algorithm, and compare its performance with the other two optimal planners stan and blackbox.