English

The signed graphs with two eigenvalues unequal to $\pm 1$

Combinatorics 2023-01-05 v1

Abstract

We complete the determination of the signed graphs for which the adjacency matrix has all but at most two eigenvalues equal to ±1\pm 1. The unsigned graphs and the disconnected, the bipartite and the complete signed graphs with this property have already been determined in two earlier papers. Here we deal with the remaining cases.

Keywords

Cite

@article{arxiv.2301.01623,
  title  = {The signed graphs with two eigenvalues unequal to $\pm 1$},
  author = {Willem Haemers and Hatice Topcu},
  journal= {arXiv preprint arXiv:2301.01623},
  year   = {2023}
}
R2 v1 2026-06-28T08:02:33.090Z