Summary information for reasoning about hierarchical plans
L de Silva, Sebastian Sardiña, Lin Padgham · RMIT Research Repository (RMIT University Library) · 2016
Hierarchically structured agent plans are important for efficient planning and acting, and they also serve (among other things) to produce 'richer' classical plans, composed not just of a sequence of primitive actions, but also 'abstract' ones representing the supplied hierarchies. A crucial step for this and other approaches is deriving precondition and effect 'summaries' from a given plan hierarchy. This paper provides mechanisms to do this for more pragmatic and conventional hierarchies than in the past. To this end, we formally define the notion of a precondition and an effect for a hierarchical plan; we present data structures and algorithms for automatically deriving this information; and we analyse the properties of the presented algorithms. We conclude the paper by detailing how our algorithms may be used together with a classical planner in order to obtain abstract plans.