AN EXCHANGE HEURISTIC FOR GENERALIZED JOB SHOP SCHEDULING

Abstract

Abstract An efficient heuristic for the generalized job shop scheduling problem, with or without multiple parallel machines, is herein presented. This heuristic, in a somewhat more general form, was explained in some detail in our earlier work in project scheduling; and we now suggest that, through this approach, problems in the areas of job shop scheduling and project scheduling may be viewed as elements of the same class. Given an initial feasible solution, the algorithm seeks to improve on this schedule through reduction of makespan by effectively identifying rearrangement opportunities. The quality of the final schedule appears to be, in general, directly correlated to the quality of the starting solution. However, it is recommended that the process be initiated with a reasonably good randomly-generated schedule, rather than a better one produced through rule-based scheduling (such as the Longest Processing Time rule), owing to the fact that such better schedules actually tend to offer less opportunit...