English

Mixed graphs with smallest eigenvalue greater than $-\frac{\sqrt{5}+1}{2}$

Combinatorics 2021-05-05 v3

Abstract

The classical problem of characterizing the graphs with bounded eigenvalues may date back to the work of Smith in 1970. Especially, the research on graphs with smallest eigenvalues not less than 2-2 has attracted widespread attention. Mixed graphs are natural generalization of undirected graphs. In this paper, we completely characterize the mixed graphs with smallest Hermitian eigenvalue greater than 5+12-\frac{\sqrt{5}+1}{2}, which consists of three infinite classes of mixed graphs and 3030 scattered mixed graphs. By the way, we get a new class of mixed graphs switching equivalent to their underlying graphs.

Keywords

Cite

@article{arxiv.2012.13149,
  title  = {Mixed graphs with smallest eigenvalue greater than $-\frac{\sqrt{5}+1}{2}$},
  author = {Lu Lu and ZhenZhen Lou},
  journal= {arXiv preprint arXiv:2012.13149},
  year   = {2021}
}

Comments

15 pages

R2 v1 2026-06-23T21:21:45.778Z