Scheduling under a common due-data on parallel unrelated machines

Due-data determination problems have gained significant attention in recent years due to the industrial focus in the just-in-time philosophy. In this paper the problem of scheduling a set of independent jobs on parallel unrelated processors under a common due-date is examined. The common due-date is a decision variable. The objective is to allocate and sequence the jobs on the machines and to determine the optimal due-data, so that the total cost be minimised. This cost is composed of the due-date assignment, the total earliness and the total tardiness cost. As the problem is NP-hard, a polynomial time heuristic procedure, which provides efficient solutions, is developed. The procedure is illustrated by means of an example and is tested via two small size experiments.