论文标题

新的复杂性和近似性结果,以最大程度地减少受到不可再生资源约束的单个机器的总加权完成时间

New complexity and approximability results for minimizing the total weighted completion time on a single machine subject to non-renewable resource constraints

论文作者

Györgyi, Péter, Kis, Tamás

论文摘要

在本文中,我们考虑了单个机器调度问题,并具有其他不可再生资源约束。不可再生资源的示例包括原材料,能源或金钱。通常,它们有初始库存,并且随着时间的推移,补充量会在A-Priori已知的时间点和数量上到达。这些工作从资源中有一些要求,只有在每个必需资源的可用数量超过工作要求的情况下才能启动工作。开始工作后,它会消耗其要求,从而减少了各个不可再生资源的可用数量。这类问题有广泛的理论和实用背景。大多数文献都集中在Makepan和最大迟到目标上。本文重点介绍了总加权完成时间目标,近似算法的列表非常短。在本文中,我们通过考虑新的特殊情况并获得新的复杂性结果和近似算法来扩展该列表。我们表明,即使只有一个不可再生的资源,每个作业都具有单位权重,并且只需要一个来自资源的单位,问题仍然是NP-HARD,但是,在我们的构建中,我们需要对输入中的作业进行高度的编码。我们还为一个变体提出了一个FPTA,其中作业具有任意权重,并且供应时间点的数量是由常数界定的。最后,我们证明了一些简单的贪婪算法为问题的一些进一步变体提供了一些非平凡的近似保证。

In this paper we consider single machine scheduling problems with additional non-renewable resource constraints. Examples for non-renewable resources include raw materials, energy, or money. Usually they have an initial stock and replenishments arrive over time at a-priori known time points and quantities. The jobs have some requirements from the resources and a job can only be started if the available quantity from each of the required resources exceeds the requirements of the job. Upon starting a job, it consumes its requirements which decreases the available quantities of the respective non-renewable resources. There is a broad theoretical and practical background for this class of problems. Most of the literature concentrate on the makespan, and the maximum lateness objectives. This paper focuses on the total weighted completion time objective for which the list of the approximation algorithms is very short. In this paper we extend that list by considering new special cases and obtain new complexity results and approximation algorithms. We show that even if there is only a single non-renewable resource, and each job has unit weight and requires only one unit from the resource, the problem is still NP-hard, however, in our construction we need a high-multiplicity encoding of the jobs in the input. We also propose an FPTAS for a variant in which the jobs have arbitrary weights, and the number of supply time points is bounded by a constant. Finally, we prove some non-trivial approximation guarantees for simple greedy algorithms for some further variants of the problem.

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