arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2007.05585math.CO
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开邻域上无着色的组合界

Combinatorial Bounds for Conflict-free Coloring on Open Neighborhoods

Sriram Bhyravarapu, Subrahmanyam Kalyanasundaram

摘要:

在无向图$G$中,关于开邻域的无冲突着色(表示为CFON着色)是对顶点的颜色分配,使得每个顶点在其开邻域中具有唯一着色的顶点。$G$的CFON着色所需的最小颜色数是$G$的CFON色数,用$χ_{ON}(G)$表示。询问$χ_{ON}(G) \leq k$是否是NP完全的决策问题。我们得到了以下结果:* Bodlaender,Kolay和Pieterse [WADS 2019]显示了上界$χ_{ON}(G)\leq {\sf fvs}(G)+3$,其中${\sf fvs}(G)$表示$G$的最小反馈顶点集的大小。我们证明了$χ_{ON}(G)\leq {\sf fvs}(G)+2$的改进界,它是紧的,从而回答了上述文件中的一个公开问题。* 本文研究了图$χ_{ON}(G)$与图$G$的路宽之间的关系,记为${\sf pw}(G)$ .上述来自WADS 2019的论文显示了上界$χ_{ON}(G) \leq 2{\sf tw}(G)+1$,其中${\sf tw}(G)$代表$G$的树宽。这意味着$χ_{ON}(G) \leq 2{\sf pw}(G)+1$的上界。给出了$χ_{ON}(G) \leq \lfloor \frac{5}{3}({\sf pw}(G)+1) \rfloor$的一个改进的界. * 我们证明$χ_{ON}(G)$的结构参数邻域多样性和聚类距离方面的新的界限,改善现有的结果。* 我们还研究了CFON着色问题的部分着色变体,它允许顶点不着色。令$χ^*_{ON}(G)$表示根据该变体为$G$着色所需的最小颜色数。Abel et.等人[SIDMA 2018]表明,当$G$为平面时,$χ^*_{ON}(G) \leq 8$。他们问,平面图的颜色是否更少就足够了。我们回答这个问题,表明$χ^*_{ON}(G) \leq 5$的所有平面$G$。我们所有的界限都是构造性算法程序的结果。

英文摘要:

In an undirected graph $G$, a conflict-free coloring with respect to open neighborhoods (denoted by CFON coloring) is an assignment of colors to the vertices such that every vertex has a uniquely colored vertex in its open neighborhood. The minimum number of colors required for a CFON coloring of $G$ is the CFON chromatic number of $G$, denoted by $χ_{ON}(G)$. The decision problem that asks whether $χ_{ON}(G) \leq k$ is NP-complete. We obtain the following results: * Bodlaender, Kolay and Pieterse [WADS 2019] showed the upper bound $χ_{ON}(G)\leq {\sf fvs}(G)+3$, where ${\sf fvs}(G)$ denotes the size of a minimum feedback vertex set of $G$. We show the improved bound of $χ_{ON}(G)\leq {\sf fvs}(G)+2$, which is tight, thereby answering an open question in the above paper. * We study the relation between $χ_{ON}(G)$ and the pathwidth of the graph $G$, denoted ${\sf pw}(G)$. The above paper from WADS 2019 showed the upper bound $χ_{ON}(G) \leq 2{\sf tw}(G)+1$ where ${\sf tw}(G)$ stands for the treewidth of $G$. This implies an upper bound of $χ_{ON}(G) \leq 2{\sf pw}(G)+1$. We show an improved bound of $χ_{ON}(G) \leq \lfloor \frac{5}{3}({\sf pw}(G)+1) \rfloor$. * We prove new bounds for $χ_{ON}(G)$ with respect to the structural parameters neighborhood diversity and distance to cluster, improving existing results. * We also study the partial coloring variant of the CFON coloring problem, which allows vertices to be left uncolored. Let $χ^*_{ON}(G)$ denote the minimum number of colors required to color $G$ as per this variant. Abel et. al. [SIDMA 2018] showed that $χ^*_{ON}(G) \leq 8$ when $G$ is planar. They asked if fewer colors would suffice for planar graphs. We answer this question by showing that $χ^*_{ON}(G) \leq 5$ for all planar $G$. All our bounds are a result of constructive algorithmic procedures.

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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