Yanbo Zhang

collaborators

3 papers

math.CO2026

Ramsey numbers and Gallai--Ramsey numbers of disjoint unions of cherries

Yanbo Zhang, Qian Chen, Yaojun Chen

For graphs $G_{1}, \dots, G_{k}$ , the Ramsey number $R (G_{1}, \dots, G_{k})$ is the smallest positive integer $N$ such that every $k$ -edge-coloring of $K_{N}$ contains a monochromatic copy of…

math.CO2026

New bounds for Ramsey numbers involving graphs with a center

Yanbo Zhang, Yaojun Chen

Let $F_{n}$ , $W_{n}$ , and $K_{n}$ be the graphs obtained by joining a vertex to $n$ independent edges, a cycle and a path of order $n - 1$ , respectively. In this paper, we give n…

math.CO2024

Disproofs of four Gallai-Ramsey-type conjectures

Yanbo Zhang, Yaojun Chen

As a significant variation of Ramsey numbers, the Gallai-Ramsey number $G R_{k} (H)$ refers to the smallest positive integer $r$ such that, by coloring the edges of $K_{r}$ with at most…