arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2103.10871math.CO
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$4$ - $χ_ρ$ -(顶点-)临界图的一个刻划

A characterization of $4$-$χ_ρ$-(vertex-)critical graphs

Jasmina Ferme

摘要:

给定一个图$G$,一个函数$c:V(G)\longrightarrow \{1,\ldots,k\}$具有性质:$c(u)=c(v)=i$蕴涵$u$和$v$之间的距离大于$i$,称为$G$的$k$ -填充染色.存在$G$的$k$ -填充染色的最小整数$k$称为$G$的填充色数,记为$χ_ρ$ .填充色顶点-临界图是指$G$的每个顶点$x$都有$χ_ρ(G-x) < χ_ρ(G)$成立的图.一个图$G$称为填充色临界图,如果对$G$的每个真子图$H$,都有$χ_ρ(H) < χ_ρ(G)$ .这两个关于填充色数的临界图的变化已经被研究过了。所有的填充色(顶点)临界图$G$与$χ_ρ(G)=3$的特征,而只有部分结果已知的图$G$与$χ_ρ(G)=4$。本文给出了所有填充色顶点-临界图$G$与$χ_ρ(G)=4$以及所有填充色临界图$G$与$χ_ρ(G)=4$的刻画.

英文摘要:

Given a graph $G$, a function $c:V(G)\longrightarrow \{1,\ldots,k\}$ with the property that $c(u)=c(v)=i$ implies that the distance between $u$ and $v$ is greater than $i$, is called a $k$-packing coloring of $G$. The smallest integer $k$ for which there exists a $k$-packing coloring of $G$ is called the packing chromatic number of $G$, and is denoted by $χ_ρ$. Packing chromatic vertex-critical graphs are the graphs $G$ for which $χ_ρ(G-x) < χ_ρ(G)$ holds for every vertex $x$ of $G$. A graph $G$ is called a packing chromatic critical graph if for every proper subgraph $H$ of $G$, $χ_ρ(H) < χ_ρ(G)$. Both of the mentioned variations of critical graphs with respect to the packing chromatic number have already been studied. All packing chromatic (vertex-)critical graphs $G$ with $χ_ρ(G)=3$ were characterized, while there were known only partial results for graphs $G$ with $χ_ρ(G)=4$. In this paper, we provide characterizations of all packing chromatic vertex-critical graphs $G$ with $χ_ρ(G)=4$ and all packing chromatic critical graphs $G$ with $χ_ρ(G)=4$.

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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