Journal of Scheduling

, Volume 16, Issue 5, pp 461-477

First online:

Semi-online scheduling problems on a small number of machines

  • Kangbok LeeAffiliated withDepartment of Supply Chain Management & Marketing Sciences, Rutgers Business School
  • , Kyungkuk LimAffiliated withBK21 Project, Sogang Business School Email author 

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We consider the semi-online parallel machine scheduling problem of minimizing the makespan given a priori information: the total processing time, the largest processing time, the combination of the previous two or the optimal makespan. We propose a new algorithm that can be applied to the problem with the known total or largest processing time and prove that it has improved competitive ratios for the cases with a small number of machines. Improved lower bounds of the competitive ratio are also provided by presenting adversary lower bound examples.


Semi-online scheduling Competitive ratio Lower bound example