Ligong Wang

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20232026

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Showing 2025 · math.COShow all

5 papers · 2 filters

math.CO2025

Spectral extremal problems for $(a, b, k)$ -critical and fractional $(a, b, k)$ -critical graphs

Zengzhao Xu, Ligong Wang, Weige Xi

A factor of a graph is essentially a specific type spanning subgraph. The study of characterizing the existence of $[a, b]$ -factors based on eigenvalue conditions can be traced bac…

math.CO2025

Spectral radius and size conditions for fractional $(a, b, m)$ -covered graphs

Zengzhao Xu, Ligong Wang, Weige Xi

A fractional $(a, b, m)$ -covered graph is a generalization of the concept of a fractional $[a, b]$ -covered graph. For any $H \subseteq G$ with edge set $∣ E (H) ∣ = m$ , if there exists a…

math.CO2025

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

Kexin Yang, Ligong Wang

Let $G$ be a simple connected graph with vertex set $V (G) = {v_{1}, v_{2}, \dots, v_{n}}$ . The distance $d_{G} (v_{i}, v_{j})$ between two vertices $v_{i}$ and $v_{j}$ of $G$ is the length of…

math.CO2025

On the distance signless Laplacian spectral radius, fractional matching and factors of graphs

Z. H. Zhang, L. G. Wang

The distance signless Laplacian matrix of a graph $G$ is define as $Q (G) =$ Tr $(G) + D (G)$ , where Tr $(G)$ and $D (G)$ are the diagonal matrix of vertex transmissions and the distance ma…

math.CO2025

Ordering digraphs with maximum outdegrees by their $A_{α}$ spectral radius

Zengzhao Xu, Weige Xi, Ligong Wang

Let $G$ be a strongly connected digraph with $n$ vertices and $m$ arcs. For any real $α \in [0, 1]$ , the $A_{α}$ matrix of a digraph $G$ is defined as $A_{α} (G) = α D (G) + (1 - α) A (G),$ where…

Spectral extremal problems for (a,b,k)-critical and fractional (a,b,k)-critical graphs

Spectral radius and size conditions for fractional (a,b,m)-covered graphs

Tricyclic graphs for which the second largest distance eigenvalue less than −21​

On the distance signless Laplacian spectral radius, fractional matching and factors of graphs

Ordering digraphs with maximum outdegrees by their Aα​ spectral radius

Spectral extremal problems for $(a, b, k)$ -critical and fractional $(a, b, k)$ -critical graphs

Spectral radius and size conditions for fractional $(a, b, m)$ -covered graphs

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

Ordering digraphs with maximum outdegrees by their $A_{α}$ spectral radius