Scheduling jobs on unrelated parallel machines so as to minimize makespan is one of the basic problems in the area of machine scheduling. In the first part of the paper, we prove that the power of preemption, i.e., the worst-case ratio between the makespan of an optimal nonpreemptive and that of an optimal preemptive schedule, is at least 4. This matches the upper bound proposed in Lin and Vitt...

A new hybrid flow shop scheduling problem with blocking is studied. The problem is characterized by multistage unrelated parallel machines and no intermediate buffer. Firstly, the math model of the hybrid scheduling problem is constructed. And then the computation method of production period is given. Due to there is no intermediate buffer, and there are unrelated parallel machines in multi-sta...

A new unrelated parallel machine scheduling problem with deteriorating 26 effect and the objective of makespan minimization is presented in this paper. The 27 deterioration of each machine (and therefore of the job processing times) is a function of the 28 sequence of jobs that have been processed by the machine and not (as considered in the 29 literature) by the time at which each job is assig...