A memory-based hierarchical planner

This paper describes a memory-based planning system. The memory constitutes a collection of generalized plans, which we call skeletons. Each skeleton embodies a style, and organizes planning knowledge in a packaging hierarchy. Traversal of this hierarchy results in hierarchical plan development, and the process is guided by a secondary memory which organizes the properties of ingredients into an inheritance hierarchy. A simple indexing hierarchy allows access to each skeleton, which is quite distinct and captures a whole class of plans in that style. Stepwise refinement of the plan is accompanied by modifications which add ingredient specific steps on the way. A system has been implemented in the culinary domain.