
1.7 A Running Example: Dock-Worker Robots 13
when other assumptions are relaxed, as we have seen in the case of nondeterministic
systems (assumption A3) or when relaxing assumptions A1, A3, A4, and A6. Plans
as partially ordered sets or as sequences of sets of actions, studied in Chapter 6 and
in Part II, are more easily handled than conditional plans and policies that will be
seen in Part V.
Relaxing Assumption A6 (Implicit Time). In many planning domains, action dura-
tion and concurrency have to be taken into account. Time may also be needed for
expressing temporally constrained goals and occurrence of events with respect to
an absolute time reference. ...