English

Tricyclic graphs for which the second largest distance eigenvalue less than $-\frac{1}{2}$

Combinatorics 2025-09-17 v1

Abstract

Let GG be a simple connected graph with vertex set V(G)={v1,v2,,vn}V(G)=\{v_{1}, v_{2}, \ldots, v_{n}\}. The distance dG(vi,vj)d_G(v_i,v_j) between two vertices viv_i and vjv_j of GG is the length of a shortest path between viv_i and vjv_j. The distance matrix of GG is defined as D(G)=(dG(vi,vj))n×nD(G)=(d_G(v_i,v_j))_{n\times n}. The second largest distance eigenvalue of G G is the second largest eigenvalues of D(G)D(G). Guo and Zhou [Discrete Math. 347(2024), 114082] proved that any connected graph with the second largest distance eigenvalue less than 12-\frac{1}{2} is chordal, and characterize all bicyclic graphs and split graphs with the second largest distance eigenvalue less than 12-\frac{1}{2}. Based on this, we characterize all tricyclic graphs with the second largest distance eigenvalue less than 12-\frac{1}{2}.

Keywords

Cite

@article{arxiv.2509.12640,
  title  = {Tricyclic graphs for which the second largest distance eigenvalue less than $-\frac{1}{2}$},
  author = {Kexin Yang and Ligong Wang},
  journal= {arXiv preprint arXiv:2509.12640},
  year   = {2025}
}
R2 v1 2026-07-01T05:38:20.915Z