Zenan Du

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20222026

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Showing math.COShow all

4 papers · 1 filter

math.CO2026

Signed graphs with exactly two main eigenvalues: The unicyclic case

Zenan Du, Fenjin Liu, Hechao Liu +2

An eigenvalue $λ$ of a signed graph $S$ of order $n$ is called a main eigenvalue if its eigenspace is not orthogonal to the all-ones vector $j$ . Characterizing signed graphs with e…

math.CO2025

Signless Laplacian spectral conditions for even factors in graphs

Lu Li, Hechao Liu, Hongbo Hua +1

A spanning subgraph $F$ of a graph $G$ is defined as an even factor of $G$ , if the degree $d_{F} (v) = 2 k, k \in N^{+}$ for every vertex $v \in V (G)$ . This note establishes a suffic…

math.CO2024

Spectral conditions for spanning $k$ -trees or $k$ -ended-trees of $t$ -connected graphs

Jifu Lin, Zenan Du, Xinghui Zhao +1

Let $G$ be a connected graph of order $n$ . A spanning $k$ -tree of $G$ is a spanning tree with the maximum degree at most $k$ , and a spanning $k$ -ended-tree of $G$ is a spanning tre…

math.CO2022

The Sombor index and coindex of two-trees

Zenan Du, Lihua You, Hechao Liu +1

The Sombor index of a graph $G$ , introduced by Ivan Gutman, is defined as the sum of the weights $d_{G} (u)^{2} + d_{G} (v)^{2}$ of all edges $uv$ of $G$ , where $d_{G} (u)$ denotes the deg…

Signed graphs with exactly two main eigenvalues: The unicyclic case

Signless Laplacian spectral conditions for even factors in graphs

Spectral conditions for spanning k-trees or k-ended-trees of t-connected graphs

The Sombor index and coindex of two-trees

Spectral conditions for spanning $k$ -trees or $k$ -ended-trees of $t$ -connected graphs