SOLVING SCHEDULING PROBLEM WITH TIME DEPENDENT LEARNING EFFECT TO NUMBER OF TARDY JOBS AND RANGE OF LATENESS CRITERIA

In traditional scheduling problems, most literature assumes that the processing time of a job is fixed. however, there are many situations where the processing time of a job depends on the starting time or the position of the job in a sequence. in such situations, the actual processing time of a job may be more or less than its normal processing time if it is scheduled later. this phenomenon is known as the ‘‘learning effect’’. in this study, we introduce a time-dependent learning effect into a single-machine scheduling problem. we consider the following objective function minimize range of lateness subject to the number of tardy jobs. a non-linear programming model is developed for the problem which belongs to np-hard class. also the model is tested on an example.