Scheduling
In this planning module detailed scheduling problems are solved. Thousands of problem-specific planning models and solution approaches are available in the literature. One of the simplest problems is to find the sequence of jobs with different processing times that wait at a given point in time at a single machine. If the objective is to minimize the average flow time of all jobs, then this single-machine sequencing problem can be solved by sorting the jobs in ascending order according to their processing time (SPT, shortest processing time rule) and process the jobs in that order. Other problem scenarios, including multiple machines with multiple production stages, are much more complicated.
The detailed scheduling module of a typical Advanced Planning System usually is built on a fairly general model specification of the considered scheduling problem, which is then solved with a general-purpose algorithm, such as a genetic algorithm.