On the Utility of Systematicity: Understanding Tradeoffs Between Redundancy and Commitment in Partial-Ordering Planning

In this paper we shall argue that the performance of a POPI planner depends more closely on the way it deals with the tradeoff between redundancy and commitment, than with the systematicity of its search. We will start with a rational reconstruction of the motivations behind systematicity in POPI planning and show that systematicity is just one extreme solution for the tradeoff between redundancy and commitment. We will show that there are a spectrum of solutions to this tradeoff, and identify the dimensions along which they vary. We will explore the relative utility of the different solutions through a comparative study of seven planners that fall at different points on the spectrum.