研究带有共同交货期的三台平行机排序问题.工件在加工过程中不允许中断,目标是极大化所有工件的提前完工量,即在交货期前所加工工件(或部分)的总加工时长.由于该问题是NP-难问题,本文应用经典LPT算法来解决该问题.我们证明了LPT算法求解该问题的最坏情况界至多为15,并给出实例说明最坏情况界的下界为27-25.

This paper investigates the parallel scheduling problem with a new feature that service requests from various customers who are entitled to many different grades of service(GOS) levels.Hence each job and machine are labelled with the GOS levels,and each job can be processed by a particular machine only when the GOS level of the job is not less than that of the machine.The objective is to minimize the makespan.This problem is proposed by HWANG et al.recently.For this problem,we present an algorithm,based on techniques from 'bin-packing',with a worst-case ratio of 32+(12)k for any m≥3,where k is the desired number of iteration,which improves the known result 2-1/m-1.