English

Neumaier graphs with few eigenvalues

Combinatorics 2020-07-16 v1

Abstract

A Neumaier graph is a non-complete edge-regular graph containing a regular clique. In this paper we give some sufficient and necessary conditions for a Neumaier graph to be strongly regular. Further we show that there does not exist Neumaier graphs with exactly four distinct eigenvalues. We also determine the Neumaier graphs with smallest eigenvalue -2.

Keywords

Cite

@article{arxiv.2007.07520,
  title  = {Neumaier graphs with few eigenvalues},
  author = {Aida Abiad and Bart De Bruyn and Jozefien D'haeseleer and Jack H. Koolen},
  journal= {arXiv preprint arXiv:2007.07520},
  year   = {2020}
}
R2 v1 2026-06-23T17:07:54.895Z