Junjie Wang

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5 papers · 1 filter

math.CO2026

On a conjecture of Kolokolnikov on algebraic connectivity

Cheng Chi, Junjie Wang, Jiaxin Zheng

For a graph $G$ , let $α (G)$ be the second smallest eigenvalue of the Laplacian matrix of $G$ , also known as the algebraic connectivity. Algebraic connectivity plays an important ro…

math.CO2026

A lifting theorem for generalized Turán numbers of triangles

Junjie Wang, Yaoping Hou

For graphs $H$ and $F$ , the generalized Turán number $ex (n, H, F)$ denotes the maximum number of copies of $H$ in an $n$ -vertex $F$ -free graph. We prove a general lift…

math.CO2023

Spectral condition for the existence of a chorded cycle

Jiaxin Zheng, Xueyi Huang, Junjie Wang

A chord of a cycle $C$ is an edge joining two non-consecutive vertices of $C$ . A cycle $C$ in a graph $G$ is chorded if the vertex set of $C$ induces at least one chord. In this pa…

math.CO2023

Turán problem for $C_{2 k + 1}^{-}$ -free signed graph

Junjie Wang, Yaoping Hou, Xueyi Huang

In this paper, we study the Turán problem for $C_{2 k + 1}^{-}$ . Suppose that $G ˙$ is an unbalanced signed graph of order $n$ with $e (G ˙)$ edges. Let $λ_{1} (G ˙)$ be th…

math.CO2022

Spectral radius conditions for fractional $[a, b]$ -covered graphs

Junjie Wang, Jiaxin Zheng, Yonglei Chen

A graph $G$ is called fractional $[a, b]$ -covered if for every edge $e$ of $G$ there is a fractional $[a, b]$ -factor with the indicator function $h$ such that $h (e) = 1$ . In this paper…

On a conjecture of Kolokolnikov on algebraic connectivity

A lifting theorem for generalized Turán numbers of triangles

Spectral condition for the existence of a chorded cycle

Turán problem for C2k+1−​-free signed graph

Spectral radius conditions for fractional [a,b]-covered graphs

Turán problem for $C_{2 k + 1}^{-}$ -free signed graph

Spectral radius conditions for fractional $[a, b]$ -covered graphs