What to Do if a Plan Does Not Comply with an HTN Model?

Abstract

Plan verification deals with the problem of checking whether a given sequence of actions is a valid plan according to a planning domain model. If the action sequence is not a valid plan, the next question is where the problem is. This question can be addressed by plan correction - modifying the plan to get a valid plan. The paper presents the first system to correct totally ordered hierarchical plans by action deletion and action insertion. Supporting action insertion, which is the major novelty here, significantly extends the applicability of plan correction to areas such as plan recognition and even planning itself. The new system is also faster than the existing plan correction system when only action deletion is allowed.