Operations Research Transactions ›› 2026, Vol. 30 ›› Issue (1): 188-196.doi: 10.15960/j.cnki.issn.1007-6093.2026.01.013

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Approximation algorithm for mixed batch parallel machine scheduling with nested processing set restrictions

WU Hongyi1, WANG Dong1, WAN Long2, LUO Wenchang1,†   

  1. 1. School of Mathematics and Statistics, Ningbo University, Ningbo 315211, Zhejiang, China;
    2. School of Information Management, Jiangxi University of Finance and Economics, Nanchang 330013, Jiangxi, China
  • Received:2022-12-22 Published:2026-03-16

Abstract: In this paper, we investigate the mixed batch parallel machine scheduling problem in which a set of jobs should be processed on one of the parallel batch machines with nested processing set restrictions. Each job has its processing time and its machine set for processing with these machine sets satisfying the nested processing set restrictions. Each machine can process a group of jobs as a batch simultaneously, as long as the total number of jobs in this batch does not exceed the capacity of the machine. For a given batch, its processing time is equal to the weighted sum of the maximum processing time and the total processing time of jobs in the batch. The objective function is to minimize the makespan. The problem includes the classic parallel machine scheduling problem as a special case, which is strongly NP-hard. For the studied problem, we derive an approximation algorithm with a performance ratio of $\left({2 + \alpha} \right)$, where $\alpha$ is a given parameter for weight with $0\leq\alpha\leq 1$.

Key words: mixed batch scheduling, nested processing set, makespan, approximation algorithm

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