A Theory of Conflict Resolution in Planning

Connict resolution in planning is the process of constraining a plan to remove harmful interactions that threaten its correctness. It has been a major contributing factor to the complexity of classical planning systems. Traditional planning methods have dealt with the problem of connict resolution in a local and incremental manner, by considering and resolving connicts individually. This paper presents a theory of connict resolution that supports a global consideration of connicts. The theory enables one to formally represent, reason about and resolve connicts using an extended framework of constraint satisfaction. The computational advantage of the theory stems from its ability to remove inconsistencies early in a search process, to detect deadends with low computational overhead, to remove redundancies in a search space, and to guide the search by providing an intelligent order in which to resolve connicts. The paper also presents empirical results showing the utilities of the theory, by investigating the characteristics of problem domains where the theory is expected to work well, and the types of planning systems for which the theory can ooer a marked computational advantage.