
15.2 Elements of Scheduling Problems 351
may be unnecessary: if one is not interested in distinguishing between these five
cranes, backtracking on this choice is meaningless. If this set of cranes is modeled
as a resource, then a load action reduces during its duration the number of available
cranes by one. The choice of which of the five cranes will be used is not a decision
point at planning time. The set of robots in the DWR domain can also be modeled
as a resource if they are considered to be identical or as several resources corre-
sponding to the different types of available robots (see Section 20.4). Containers,
on the other hand, cannot be modeled ...