English

Laplacian Spectra of Comaximal Graph of $\mathbb{Z}_{n}$

Combinatorics 2021-11-24 v2

Abstract

This article focuses on finding the eigenvalues of the Laplacian matrix of the comaximal graph Γ(Zn)\Gamma(\mathbb Z_n) of the ring Zn\mathbb Z_n for n>2n> 2. We determine the eigenvalues of Γ(Zn)\Gamma(\mathbb Z_n) for various nn and also provide a procedure to find the eigenvalues of Γ(Zn)\Gamma(\mathbb Z_n) for any n>2n> 2. We show that Γ(Zn)\Gamma(\mathbb Z_n) is Laplacian Integral for n=pαqβn=p^\alpha q^\beta where p,qp,q are primes and α,β\alpha, \beta are non-negative integers. The algebraic and vertex connectivity of Γ(Zn)\Gamma(\mathbb Z_n) have been shown to be equal for all n>2n> 2. An upper bound on the second largest eigenvalue of Γ(Zn)\Gamma(\mathbb Z_n) has been obtained and a necessary and sufficient condition for its equality has also been determined. Finally we discuss the multiplicity of the spectral radius and the multiplicity of the algebraic connectivity of Γ(Zn)\Gamma(\mathbb Z_n). Some problems have been discussed at the end of this article for further research.

Keywords

Cite

@article{arxiv.2005.02316,
  title  = {Laplacian Spectra of Comaximal Graph of $\mathbb{Z}_{n}$},
  author = {Subarsha Banerjee},
  journal= {arXiv preprint arXiv:2005.02316},
  year   = {2021}
}