Memetic Algorithm for Flexible Job Shop Scheduling with Preemption

Flexible job shop scheduling problem)FJSP(is an extension of the classical job shop scheduling problem which allows an operation to be processed by any machine from a given set. FJSP is NP-hard and mainly presents two difficulties. The first one is to assign each operation to a machine out of a set of capable machines, and the second one deals with sequencing the assigned operations on the machines. However, it is quite difficult to achieve an optimal solution to this problem in medium and large size problems with traditional optimization approaches. In this paper a memetic algorithm (MA) or flexible job shop scheduling with overlapping in operation is proposed that solves the FJSP to minimize makespan time and obtain the optimum solution for small problem and best solution for medium and large scale problems. In this paper we also used preemption to improve the results of memetic algorithm and reduce the makespan.