Abstract This paper investigates the set partitioning containing kernels. This problem can also be considered as the identical machine scheduling problem with nonsimultaneous machine release times. That the algorithm ...Abstract This paper investigates the set partitioning containing kernels. This problem can also be considered as the identical machine scheduling problem with nonsimultaneous machine release times. That the algorithm MULTIFIT has a worst case bound of 6/5 is proved. Through combining MULTIFIT and LPT, an algorithm MULTILPT with a worst case bound of 7/6 has been obtained.展开更多
In this paper, we investigate the/-preemptive scheduling on parallel machines to maximize the minimum machine completion time, i.e., machine covering problem with limited number of preemptions. It is aimed to obtain t...In this paper, we investigate the/-preemptive scheduling on parallel machines to maximize the minimum machine completion time, i.e., machine covering problem with limited number of preemptions. It is aimed to obtain the worst case ratio of the objective value of the optimal schedule with unlimited preemptions and that of the schedule allowed to be preempted at most i times. For the m identical machines case, we show the worst case ratio is 2m-i-1/m and we present a polynomial time algorithm which can guarantee the ratio for any 0 〈 i 〈2 m - 1. For the /-preemptive scheduling on two uniform machines case, we only need to consider the cases of i = 0 and i = 1. For both cases, we present two linear time algorithms and obtain the worst case ratios with respect to s, i.e., the ratio of the speeds of two machines.展开更多
文摘Abstract This paper investigates the set partitioning containing kernels. This problem can also be considered as the identical machine scheduling problem with nonsimultaneous machine release times. That the algorithm MULTIFIT has a worst case bound of 6/5 is proved. Through combining MULTIFIT and LPT, an algorithm MULTILPT with a worst case bound of 7/6 has been obtained.
基金Supported by the National Natural Science Foundation of China(11001242,11071220)
文摘In this paper, we investigate the/-preemptive scheduling on parallel machines to maximize the minimum machine completion time, i.e., machine covering problem with limited number of preemptions. It is aimed to obtain the worst case ratio of the objective value of the optimal schedule with unlimited preemptions and that of the schedule allowed to be preempted at most i times. For the m identical machines case, we show the worst case ratio is 2m-i-1/m and we present a polynomial time algorithm which can guarantee the ratio for any 0 〈 i 〈2 m - 1. For the /-preemptive scheduling on two uniform machines case, we only need to consider the cases of i = 0 and i = 1. For both cases, we present two linear time algorithms and obtain the worst case ratios with respect to s, i.e., the ratio of the speeds of two machines.
