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arXiv 1305.2986math.CO
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有向图的明智划分

Judicious partitions of directed graphs

Choongbum Lee, Po-Shen Loh, Benny Sudakov

摘要:

明智划分领域考虑了划分问题的一般家族,其中一个寻求同时优化多个参数,并且这些问题已经在各种组合背景下被广泛研究。在本文中,我们研究本质上是最基本的明智的分区问题的有向图,这自然扩展了经典的最大割问题,这个设置:我们寻求bipartisons中,许多边缘在每个方向交叉。很容易看出,一个最小出度条件是必要的,以便问题是非平凡的,我们证明了每一个有向图的M条边和最小出度至少为2承认一个双划分,其中至少有(1/6 + o(1))M条边在每个方向上交叉。我们还证明了,如果最小出度至少是3,那么常数可以增加到1/5。如果最小出度随N趋于无穷大,则常数增加到1/4。所有这些常数都是最佳可能的,并为亚历克斯·斯科特的问题提供了渐进答案。

英文摘要:

The area of judicious partitioning considers the general family of partitioning problems in which one seeks to optimize several parameters simultaneously, and these problems have been widely studied in various combinatorial contexts. In this paper, we study essentially the most fundamental judicious partitioning problem for directed graphs, which naturally extends the classical Max Cut problem to this setting: we seek bipartitions in which many edges cross in each direction. It is easy to see that a minimum outdegree condition is required in order for the problem to be nontrivial, and we prove that every directed graph with M edges and minimum outdegree at least two admits a bipartition in which at least (1/6 + o(1))M edges cross in each direction. We also prove that if the minimum outdegree is at least three, then the constant can be increased to 1/5. If the minimum outdegree tends to infinity with N, then the constant increases to 1/4. All of these constants are best-possible, and provide asymptotic answers to a question of Alex Scott.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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