English

Graphs whose normalized Laplacian has three eigenvalues

Combinatorics 2012-02-15 v1

Abstract

We give a combinatorial characterization of graphs whose normalized Laplacian has three distinct eigenvalues. Strongly regular graphs and complete bipartite graphs are examples of such graphs, but we also construct more exotic families of examples from conference graphs, projective planes, and certain quasi-symmetric designs.

Keywords

Cite

@article{arxiv.1202.3027,
  title  = {Graphs whose normalized Laplacian has three eigenvalues},
  author = {Edwin R. van Dam and Gholamreza Omidi},
  journal= {arXiv preprint arXiv:1202.3027},
  year   = {2012}
}
R2 v1 2026-06-21T20:19:11.146Z