Generating Parallel Execution Plans with a Partial-order Planner

Many real-world planning problems require generating plans that maximize the parallelism inherent in a problem. There are a number of partial-order planners that generate such plans; however, in most of these planners it is unclear under what conditions the resulting plans will be correct and whether the planner can even find a plan if one exists. This paper identifies the underlying assumptions about when a partial plan can be executed in parallel, defines the classes of parallel plans that can be generated by different partial-order planners, and describes the changes required to turn UCPOP into a parallel execution planner. In addition, we describe how this planner can be applied to the problem of query access planning, where parallel execution produces substantial reductions in overall execution time.