arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1207.0932cs.DM
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折叠图

Folding graphs

Ton Kloks, Yue-Li Wang

摘要:

设G是一个图。考虑两个不相邻的顶点x和y有一个共同的邻居。关于x和y折叠G是标识x和y的运算。在一个极大的折叠级数之后,图是一个不相交的团并。最大折叠级数后出现的最小团数等于G的色数。本文研究了确定一个极大折叠级数后所能出现的最大团数的问题。我们把这个数记为Sigma(G),称之为最大折叠数。我们表明,这个问题是NP-完全的,即使限制到类,如平凡完美图,cobipartite图和平面图。我们证明了树的最大折叠数是2。

英文摘要:

Let G be a graph. Consider two nonadjacent vertices x and y that have a common neighbor. Folding G with respect to x and y is the operation which identifies x and y. After a maximal series of foldings the graph is a disjoint union of cliques. The minimal clique number that can appear after a maximal series of foldings is equal to the chromatic number of G. In this paper we consider the problem to determine the maximal clique number which can appear after a maximal series of foldings. We denote this number as Sigma(G) and we call it the max-folding number. We show that the problem is NP-complete, even when restricted to classes such as trivially perfect graphs, cobipartite graphs and planar graphs. We show that the max-folding number of trees is two.

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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