Defining the Problem, Designing a Model
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| IBM ILOG Scheduler User's Manual > Advanced Concepts > Scheduling with Discrete Resources: the Ship-loading Problem > Defining the Problem, Designing a Model |
Defining the Problem, Designing a Model |
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The first step consists of defining the problem.
IloDiscreteResource represents the resource, and the capacity of the resource is passed as an argument to the constructor.
IloActivity represent the activities, and again, the duration of each activity is passed as an argument to the constructor.
IloActivity::startsAfterEnd declares the precedence constraints.
requires member function of the class IloActivity is used to declare the resource requirement constraints.
The underlying constraint propagation mechanism in Scheduler systematically updates the earliest and latest start and end times for activities when decisions are made. For each activity A, it is guaranteed that the earliest and latest start and end times of A are consistent with the temporal constraints and with the resource requirements of "scheduled" activities (that is, activities for which the start and end times have been fixed).1 This fact, in turn, guarantees that any attempt to fix the start and end times of all activities will succeed only if the chosen start and end times satisfy all the constraints of the problem.
1This does not mean that the earliest and latest start and end times of all activities (scheduled and unscheduled) are globally consistent. It is necessary to explore the search space to determine a globally consistent solution.
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