English

The Hoffman program for mixed graphs

Combinatorics 2025-08-06 v2

Abstract

We consider Hoffman's program about the limit points of the spectral radius of the Hermitian adjacency matrix of mixed graphs. In particular, we determine all mixed graphs without negative 44-cycle whose spectral radius does not exceed 2+5\sqrt{2+\sqrt{5}}, and identify all limit points of spectral radii of mixed graphs.

Keywords

Cite

@article{arxiv.2406.18318,
  title  = {The Hoffman program for mixed graphs},
  author = {Yuantian Yu and Edwin R. van Dam},
  journal= {arXiv preprint arXiv:2406.18318},
  year   = {2025}
}

Comments

17 pages, 12 figures

R2 v1 2026-06-28T17:19:52.548Z