Chapter 13 - Time for Planning

Abstract

This chapter presents temporal representations and temporal reasoning techniques that are useful to planning with time and resources. In planning, temporal relations can be conveniently represented and handled with constraint satisfaction problem (CSP)-based approaches and techniques. Two main formalisms for qualitative relations are developed—the time-point algebra, and the interval algebra. PA enable to relate in time a set of instants with qualitative constraints without necessarily ordering them. IA enables to relate in time a set of intervals with qualitative constraints. The relationships between these two formalisms are discussed. The quantitative temporal constraint networks are also introduced in the chapter. A calculus for relating a set of instants with quantitative, absolute, and relative numerical constraints is developed. The simple case where every constraint is a simple interval and the general case where disjunctions of intervals are allowed are explained in the chapter.