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Forbidden subgraphs in enhanced power graphs of finite groups

Xuanlong Ma, Samir Zahirović, Yubo Lv, Yanhong She

Abstract

The enhanced power graph of a group is the simple graph whose vertex set is consisted of all elements of the group, and whose any pair of vertices are adjacent if they generate a cyclic subgroup. In this paper, we classify all finite groups whose enhanced power graphs are split and threshold. We also classify all finite nilpotent groups whose enhanced power graphs are chordal graphs and cographs. Finally, we give some families of non-nilpotent groups whose enhanced power graphs are chordal graphs and cographs. These results partly answer a question posed by Peter J. Cameron.

Forbidden subgraphs in enhanced power graphs of finite groups

Abstract

The enhanced power graph of a group is the simple graph whose vertex set is consisted of all elements of the group, and whose any pair of vertices are adjacent if they generate a cyclic subgroup. In this paper, we classify all finite groups whose enhanced power graphs are split and threshold. We also classify all finite nilpotent groups whose enhanced power graphs are chordal graphs and cographs. Finally, we give some families of non-nilpotent groups whose enhanced power graphs are chordal graphs and cographs. These results partly answer a question posed by Peter J. Cameron.

Paper Structure

This paper contains 7 sections, 18 theorems, 15 equations, 1 figure.

Key Result

Lemma 2.1

Let $G$ be a group and $H$ its subgroup. If $\mathcal{P}_{e}(G)$ is split, threshold, chordal, chordal, or a cograph, then $\mathcal{P}_e(H)$ is also split, threshold, chordal, chordal, or a cograph, respectively.

Figures (1)

  • Figure 1:

Theorems & Definitions (23)

  • Lemma 2.1
  • Lemma 2.2
  • Lemma 3.1
  • Lemma 3.2
  • Theorem 3.3
  • Lemma 4.1
  • Lemma 4.2
  • Theorem 4.3
  • Corollary 4.4
  • Remark 4.5
  • ...and 13 more