Effects of symbiotic evolution in genetic algorithms for job-shop scheduling

In our research, we showed results of the comparative study on the effects of using several kinds of scheduling evaluation criteria as the fitness function of a genetic algorithm for job shop scheduling. From these results, we obtained that the idle time criterion sometimes can provide a good makespan-minimizing schedule for a job-shop scheduling problem. In this paper, according to the above results, we propose a symbiotic genetic algorithm. The symbiotic genetic algorithm is structured with two kinds of evolution processes: a co-evolution process in which both makespan and idle time schedule criteria are employed as the fitness functions into the operation-based genetic algorithm for job-shop scheduling; and a sub-evolution process in which the total job waiting time schedule criterion is used as the fitness to provide high diversity for chromosome population. The symbiotic genetic algorithm is tested on famous benchmark job-shop scheduling problems. Further, we introduce the concept of software system for job-shop scheduling based on the proposed method.