Evolutionary programming for minimizing the average flow time in the presence of non-zero ready times

In this paper, first manufacturing scheduling is briefly discussed and later the problem studied is introduced. The optimal solution to minimizing the average flow time in single machine scheduling is obtained by the Shortest Processing Time rule if ready times are zero for all jobs. In the case of non-zero ready times, preemption plays a key role in the solution. Preemption allowed version is solved optimally by using the Shortest Remaining Processing Time procedure. However, the version of preemption not allowed is known as NP-hard and delay and nondelay strategies might be used in a hybrid fashion. This paper focuses on minimizing the average flow time in the presence of non-zero times and when preemption is not allowed. The proposed method is evolutionary programming (EP). The results indicate that EP produces near optimal and consistent results in a short period of time.