Yanbo Zhang

activity

20242026

collaborators

10 papers

math.CO2026

Erdős--Ko--Rado theorems in $ℓ_{2}$ -norm for three finite spaces

Qian Bao, Yaojun Chen, Yanbo Zhang

Let $F$ be a $k$ -uniform hypergraph. The famous Erdős--Ko--Rado (1961) theorem determines the maximum size and extremal structure for $F$ being $t$ -intersecting…

math.CO2026

A note on tree-cycle Ramsey numbers

Ting Huang, Yanbo Zhang, Yaojun Chen

Let $R (T_{n}, C_{m})$ denote the Ramsey number of a tree $T_{n}$ on $n$ vertices versus a cycle $C_{m}$ of length $m$ . Burr, Erdős, Faudree, Rousseau, and Schelp (1982) asked for the least…

math.CO2026

Online Ramsey numbers of the claw versus cycles

Hexuan Zhi, Yanbo Zhang

The online Ramsey number $r ~ (G, H)$ is defined via a Builder--Painter game on an empty graph with countably many vertices. In each round, Builder reveals an edge, which Painte…

math.CO2025

Fan-goodness of sparse graphs

Ting Huang, Yanbo Zhang, Yaojun Chen

Let $G$ be a connected graph of order $n$ , $F_{k}$ be a fan consisting of $k$ triangles sharing a common vertex, and $t F_{k}$ be $t$ vertex-disjoint copies of $F_{k}$ . Brennan (2017) sho…

math.CO2025

Ramsey numbers of sparse graphs versus disjoint books

Ting Huang, Yanbo Zhang, Yaojun Chen

Let $B_{k}$ denote a book on $k + 2$ vertices and $t B_{k}$ be $t$ vertex-disjoint $B_{k}$ 's. For any integers $k \geq 2$ and $t \geq 1$ , there exists a positive constant $ε = ε (k, t)$ such that eve…

math.CO2025

Minimum degree and sparse connected spanning subgraphs

Ting Huang, Yanbo Zhang, Yaojun Chen

Let $G$ be a connected graph on $n$ vertices and at most $n (1 + ε)$ edges with bounded maximum degree, and $F$ a graph on $n$ vertices with minimum degree at least $n - k$ , where $ε$ i…

math.CO2025

Ramsey goodness of stars and fans for the Hajós graph

Jiafu He, Haiyu Zeng, Yanbo Zhang

Given two graphs $G_{1}$ and $G_{2}$ , the Ramsey number $R (G_{1}, G_{2})$ denotes the smallest integer $N$ such that any red-blue coloring of the edges of $K_{N}$ contains either a red $G_{1}$ …

math.CO2025

Trichotomy and $t K_{m}$ -goodness of sparse graphs

Yanbo Zhang, Yaojun Chen

Let $G$ be a connected graph with $n$ vertices and $n + k - 2$ edges and $t K_{m}$ denote the disjoint union of $t$ complete graphs $K_{m}$ . In this paper, by developing a trichotomy for sp…

math.CO2025

Turán problems for suspension of a balanced tree

Xiutao Zhu, Xiaolin Wang, Yanbo Zhang +1

The Turán number $\ex(n,H)$ is the maximum number of edges that an $n$ -vertex $H$ -free graph can have. The suspension $H$ is obtained from $H$ by adding a new vertex whic…

math.CO2024

Improved bound on the number of edges of diameter- $k$ -critical graphs

Xiaolin Wang, Yanbo Zhang, Xiutao Zhu

A graph is diameter- $k$ -critical if its diameter equals $k$ and the deletion of any edge increases its diameter. The Murty-Simon Conjecture states that for any diameter-2-critical…

Erdős--Ko--Rado theorems in ℓ2​-norm for three finite spaces

A note on tree-cycle Ramsey numbers

Online Ramsey numbers of the claw versus cycles

Fan-goodness of sparse graphs

Ramsey numbers of sparse graphs versus disjoint books

Minimum degree and sparse connected spanning subgraphs

Ramsey goodness of stars and fans for the Hajós graph

Trichotomy and tKm​-goodness of sparse graphs

Turán problems for suspension of a balanced tree

Improved bound on the number of edges of diameter-k-critical graphs

Erdős--Ko--Rado theorems in $ℓ_{2}$ -norm for three finite spaces

Trichotomy and $t K_{m}$ -goodness of sparse graphs

Improved bound on the number of edges of diameter- $k$ -critical graphs