Jiming Guo

collaborators

3 papers

math.CO2026

Upper bounds of the second largest eigenvalue of graphs

Zhiwen Wang, Zihao Geng, Ji-Ming Guo

Let $λ_{i} (G)$ denote the $i$ -th largest eigenvalue of adjacency matrix of a graph $G$ . Gerschgorin's Theorem indicates $λ_{1} (G)$ belongs to the largest disk, i.e., $λ_{1} (G) \leq Δ_{1} (G)$ ,…

math.CO2026

Extremal results on the second largest eigenvalue of graphs with given order

Zhiwen Wang, Ji-Ming Guo

In this paper, we demonstrate the effects on the second largest eigenvalue $λ_{2} (G)$ of a connected graph $G$ after edge addition or deletion. In 1989, Chung, Graham and Wilson show…

math.CO2019

On the rank (nullity) of a connected graph

Zhiwen Wang, Jiming Guo

The rank $r (G)$ of a graph $G$ is the rank of its adjacency matrix $A (G)$ and the nullity $η (G)$ of $G$ is the multiplicity of $0$ as an eigenvalue of $A (G)$ . In this paper, we pro…