Isolating where planning and scheduling interact

In many cases it is possible to separate out the causal and temporal reasoning needed for temporal planning into classical planning and scheduling. However, where the two problems are tightly coupled, that is, where there are temporal constraints encoded in the problem which will affect the choice of action, this strategy can lead to producing un-schedulable plans. This paper analyses where such cases can arise through encoding temporal constraints as durative actions and then examining where the constraints can be broken. It is found that it is not always possible to translate the problem to loosen the coupling. One option still open is to leave the problems connected only where necessary. The paper looks at how this could be done and the advantage of taking this approach.