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Spectral radius and second largest eigenvalues of power graphs of finite groups

Priti Prasanna Mondal, Basit Auyoob Mir, Fouzul Atik

Abstract

Consider a group $\mathbb{G}$ and construct its power graph, whose vertex set consists of the elements of $\mathbb{G}$. Two distinct vertices (elements) are adjacent in the graph if and only if one element can be expressed as an integral power of the other. In this article, we improved the bounds of the spectral radius of the power graphs of the cyclic group $C_{n}$, the dihedral group $\mathcal{D}_{2n}$, and the dicyclic group $\mathcal{Q}_{4n}$. For $n\neq p^{m},$ the power graph of the cyclic group $C_{n}$ is not a complete multipartite graph. We find the second largest eigenvalue bounds of the same with the clique number. In some cases, we find the bounds are exact if and only if they belong to a particular family of graphs. Lastly, we work on the distance spectral radius of the power graphs of the same groups

Spectral radius and second largest eigenvalues of power graphs of finite groups

Abstract

Consider a group and construct its power graph, whose vertex set consists of the elements of . Two distinct vertices (elements) are adjacent in the graph if and only if one element can be expressed as an integral power of the other. In this article, we improved the bounds of the spectral radius of the power graphs of the cyclic group , the dihedral group , and the dicyclic group . For the power graph of the cyclic group is not a complete multipartite graph. We find the second largest eigenvalue bounds of the same with the clique number. In some cases, we find the bounds are exact if and only if they belong to a particular family of graphs. Lastly, we work on the distance spectral radius of the power graphs of the same groups

Paper Structure

This paper contains 10 sections, 19 theorems, 77 equations, 2 figures.

Key Result

Theorem 1.1

Brow Let $A$ be a symmetric matrix whose rows and columns are partitioned according to $\{X_1,X_2,\ldots,X_m\}$, and let $Q$ be the corresponding quotient matrix. Then the eigenvalues of $Q$ interlace the eigenvalues of $A$.

Figures (2)

  • Figure 1: Induced subgraph
  • Figure 2: Power graph of $\mathbb{Z}_{6}$

Theorems & Definitions (38)

  • Theorem 1.1
  • Theorem 1.2
  • Theorem 1.3: Perron--Frobenius
  • Theorem 2.1
  • proof
  • Theorem 2.2
  • proof
  • Theorem 2.3
  • Lemma 2.1
  • proof
  • ...and 28 more