2.2.1 Job Characteristic
The first element in the scheduling problem is job characteristic where for each job j
the following features can be obtained;
Processing time (g ij ): the required time for processing job j on machine i.
Ready time (r j ): the arrival time of job j in the system for processing.
Due date (d i ): the time by which job j should be completed.
Weight (w i ): the weight (w i ) is the factor for determining the priority of execution
for each job i relative to the other jobs in the system
Additionally, its setup time does or does not allow any pre-emption. Pre-emption
(the processing of any job on a machine that can be interrupted at any time and that
allows for the processing of another job on the same machine) is allowed or not,
depending on arrival time, and departure time of other jobs. These job features can
affect the definitions of the scheduling problem types and the complexity of each
type. For example, jobs which depend on processing time only are easier to deal
with than those which depend on processing time and due date. That is, increasing
the number of features of any job can raise the complexity of the scheduling
problem. Furthermore, increasing the number of jobs inside the scheduling problem
can increase the complexity of the problem. For example, dealing with problems that
include a limited number of jobs is easier than dealing with problems that include an
unlimited number of jobs.