A Classification of Plan Modification Strategies Based on Coverage and Information Requirements

he ability to modify an existing plan to make it conform to the t f constraints of a new (or changed) planning situation is importan or plan reuse, replanning and case-based planning. While , [ significant amount of past work addressed this problem (e.g. 2, 3] [5, 1] [13] [17], [16]), there is still a lack of understanding . F of the general types of modification strategies and their coverage or example, while it is generally agreed that the information e fl about the internal structure of the plan is important to facilitat exible plan modification, the general issue of relation between e m the types of remembered information and the modification/reus ethodologies they entail has not been adequately addressed. In r the course of our research on developing , a framework fo PRIAR e d flexible plan reuse in hierarchical planning [11, 12, 10], we hav eveloped a classification of plan modification strategies based d t on the nature of the modifications that are allowed by them, an he types of information they require to facilitate those r u modifications. The motivation behind it was to classify and bette nderstand the previous work on plan modification, and to s characterize ’s approach in that spectrum. We present thi PRIAR classification in the current paper, with the belief that it can help s e in better understanding the coverage and capabilities of variou xisting plan modification strategies, and in formulating the s p directions for further research. (Much of the discussion in thi aper generalizes in part also to reuse and modification of other dependent structures such as designs and problem solutions.)