Approximability of average completion time scheduling on unrelated machines

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• 作者：René Sitters
• 关键词：Scheduling ; \(\mathcal {APX}\) ; hardness ; Approximation algorithms ; Average completion time ; Quadratic programming
• 刊名：Mathematical Programming
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：161
• 期：1-2
• 页码：135-158
• 全文大小：577KB
• 刊物类别：Mathematics and Statistics
• 刊物主题：Calculus of Variations and Optimal Control; Optimization; Mathematics of Computing; Numerical Analysis; Combinatorics; Theoretical, Mathematical and Computational Physics; Mathematical Methods in Phys
• 出版者：Springer Berlin Heidelberg
• ISSN：1436-4646
• 卷排序：161

文摘

We show that minimizing the average job completion time on unrelated machines is \(\mathcal {APX}\)-hard if preemption of jobs is allowed. This provides one of the last missing pieces in the complexity classification of machine scheduling with (weighted) sum of completion times objective. The proof is based on a mixed integer linear program. This means that verification of the reduction is partly done by an ILP-solver. This gives a concise proof which is easy to verify. In addition, we give a deterministic 1.698-approximation algorithm for the weighted version of the problem. The improvement is made by modifying and combining known algorithms and by the use of new lower bounds. These results improve on the known \(\mathcal {NP}\)-hardness and 2-approximability.