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arXiv · 2007.07520

Neumaier graphs with few eigenvalues

Aida Abiad·Bart De Bruyn·Jozefien D'haeseleer·Jack H. Koolen
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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.

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Aida Abiad, Bart De Bruyn, Jozefien D'haeseleer, Jack H. Koolen. 2020-07-15. Neumaier graphs with few eigenvalues. https://arxiv.org/abs/2007.07520

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