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Grundy coloring in some subclasses of bipartite graphs and their complements
Information Processing Letters ( IF 0.5 ) Pub Date : 2020-07-03 , DOI: 10.1016/j.ipl.2020.105999
Shaily Verma , B.S. Panda

A vertex v is a Grundy vertex with respect to a proper k-coloring c of a graph G=(V,E) if v has a neighbor of color j for every j (1j<ik), where i=c(v). A proper k-coloring c of G is called a Grundy k-coloring of G if every vertex is a Grundy vertex with respect to c and the largest integer k such that G admits a Grundy k-coloring is called the Grundy number of G which is denoted as Γ(G). Given a graph G and an integer k, the Grundy number decision problem is to decide whether Γ(G)k. The Grundy number decision problem is known to be NP-complete for bipartite graphs and complement of bipartite graphs. In this paper, we strengthen this result by showing that this problem remains NP-complete for perfect elimination bipartite graphs as well as for complement of perfect elimination bipartite graphs. Further, we give a linear-time algorithm to find the Grundy number of chain graphs, which is a proper subclass of the class of perfect elimination bipartite graphs. We also give a linear-time algorithm to find the Grundy number in complements of chain graphs. A partial Grundy coloring of a graph G is a proper k-coloring of G such that there is at least one Grundy vertex with each color i, 1ik and the partial Grundy number of G, Γ(G), is the largest integer k such that G admits a partial Grundy k-coloring. Given a graph G and an integer k, the partial Grundy number decision problem is to decide whether Γ(G)k. It is known that the partial Grundy number decision problem is NP-complete for bipartite graphs. In this paper, we prove that this problem is NP-complete in the complements of bipartite graphs by showing that the Grundy number and partial Grundy number are equal in complements of bipartite graphs.



中文翻译:

二部图及其补集的某些子类中的肮脏着色

顶点v是关于图的适当k着色cGrundy顶点G=VË如果vj有一个颜色j的邻居 1个Ĵ<一世ķ,在哪里 一世=Cv。一个适当的ķ -coloring Çģ称为格伦迪K-着色ģ如果每个顶点是相对于一个顶点格伦迪ç和最大整数ķ使得ģ承认一个格伦迪ķ -coloring称为格伦迪数目ģ其中表示为ΓG。给定一个图G和一个整数k格兰迪数决定问题是决定是否ΓGķ。对于二部图和二部图的补图,已知格伦迪数决策问题是NP完全的。在本文中,我们通过证明对于完全消除二分图以及对于完美消除二分图,该问题仍然是NP完全的,从而加强了这一结果。此外,我们给出了一个线性时间算法来找到链图的Grundy数,它是理想消除二分图类的适当子类。我们还给出了线性时间算法,以在链图的补码中找到格伦迪数。的曲线图的部分格伦迪着色ģ是一个适当的ķ -coloring的ģ使得存在至少一个顶点格伦迪与每个颜色1个一世ķ局部格伦迪数目ģΓG是最大的整数k,以使G允许部分Grundy k着色。给定一个图G和一个整数k偏葛兰迪数决定问题是决定是否ΓGķ。众所周知,对于二部图,部分Grundy数决策问题是NP完全的。在本文中,通过证明二部图的补中的格朗迪数和部分格伦迪数相等,证明了该问题在二部图的补图中是NP完全的。

更新日期:2020-07-03
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