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arXiv 2401.04789math.GRmath.CO
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有限群的Gruenberg--Kegel图的组合性质

On combinatorial properties of Gruenberg--Kegel graphs of finite groups

Mingzhu Chen, Ilya B. Gorshkov, Natalia V. Maslova, Nanying Yang

AI总结:

本文研究有限群的Gruenberg-Kegel图(素图)的组合性质,证明了偶数阶群中与2不相邻的顶点构成团的并,并给出了强正则图及完全二部图(每部分大小至少3)能否作为有限群素图的判定条件。

摘要:

若$G$是有限群,则谱$\omega(G)$是$G$的所有元素阶的集合。素谱$\pi(G)$是属于$\omega(G)$的所有素数的集合。以$\pi(G)$为顶点集,且两个不同顶点$r$和$s$相邻当且仅当$rs \in \omega(G)$的简单图$\Gamma(G)$称为$G$的Gruenberg-Kegel图或素图。在本文中,我们证明若$G$是偶数阶群,则$\Gamma(G)$中与$2$不相邻的顶点集合构成团(clique)的并。此外,我们确定了强正则图何时同构于有限群的Gruenberg-Kegel图。除此之外,我们证明每个部分大小至少为$3$的完全二部图不能同构于有限群的Gruenberg-Kegel图。

英文摘要:

If $G$ is a finite group, then the spectrum $ω(G)$ is the set of all element orders of $G$. The prime spectrum $π(G)$ is the set of all primes belonging to $ω(G)$. A simple graph $Γ(G)$ whose vertex set is $π(G)$ and in which two distinct vertices $r$ and $s$ are adjacent if and only if $rs \in ω(G)$ is called the Gruenberg-Kegel graph or the prime graph of $G$. In this paper, we prove that if $G$ is a group of even order, then the set of vertices which are non-adjacent to $2$ in $Γ(G)$ form a union of cliques. Moreover, we decide when a strongly regular graph is isomorphic to the Gruenberg-Kegel graph of a finite group. Besides this, we prove that a complete bipartite graph with each part of size at least $3$ can not be isomorphic to the Gruenberg-Kegel graph of a finite group.

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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