On the Complexity of Case-Based Planning

TL;DR

This paper investigates the computational complexity of case-based planning, showing that planning from a single case or a library remains PSPACE-complete, with complexity influenced by case domain similarity.

Contribution

It provides a formal complexity analysis of case-based planning, revealing conditions under which complexity can be reduced.

Findings

Planning from a single case is as complex as generative planning.

Using similar domain cases can reduce complexity.

Planning from a library of cases remains PSPACE-complete.

Abstract

We analyze the computational complexity of problems related to case-based planning: planning when a plan for a similar instance is known, and planning from a library of plans. We prove that planning from a single case has the same complexity than generative planning (i.e., planning "from scratch"); using an extended definition of cases, complexity is reduced if the domain stored in the case is similar to the one to search plans for. Planning from a library of cases is shown to have the same complexity. In both cases, the complexity of planning remains, in the worst case, PSPACE-complete.