English

The graphs which are cospectral with the generalized pineapple graph

Combinatorics 2024-06-11 v2

Abstract

Let p,k,qp, k, q be positive integers with p2kp-2 \geqslant k and let Kp,kqK_{p,k}^{q} be the generalized pineapple graph which is obtained by joining independent set of qq vertices with kk vertices of a complete graph Kp.K_{p}. In \cite{TSH2}, Haemers et al. constructed graphs which cospectral with Kp,1q.K_{p,1}^{q}. In this paper, we determine all graphs which are cospectral with Kp,kqK_{p,k}^{q} by considering the eigenvalues of its adjacency matrix. Moreover, We extend the conclusions of Haemers et al. to a broader context.

Keywords

Cite

@article{arxiv.2307.12501,
  title  = {The graphs which are cospectral with the generalized pineapple graph},
  author = {Borchen Li and Qingzhong Ji},
  journal= {arXiv preprint arXiv:2307.12501},
  year   = {2024}
}
R2 v1 2026-06-28T11:38:16.090Z