Yaojun Chen

activity

20222026

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6 papers · 1 filter

math.CO2026

Any $k$ -graph with zero $ℓ$ -degree Turán density is layered

Jiabao Yang, Xiaona Fang, Yaojun Chen

The codegree Turán density $π_{co} (F)$ is the supremum over all $γ \in [0, 1)$ such that, for arbitrarily large $n$ , there exists an $n$ -vertex $F$ -free $k$ -graph $H$ whose…

math.CO2026

On the codegree Turán density of projective geometries

Xiaona Fang, Yaojun Chen

Let $F$ be a $k$ -uniform hypergraph, abbreviated as $k$ -graph. The codegree Turán density $γ (F)$ is the supremum over all $γ \in [0, 1)$ such that, for arbitrarily large $n$ , there e…

math.CO2026

On linear $k$ -graphs with codegree Turán density arbitrarily close to zero

Xiaona Fang, Yaojun Chen

Let $F$ be a $k$ -uniform hypergraph, abbreviated as $k$ -graph. The codegree Turán density $π_{co} (F)$ is the supremum over all $γ \in [0, 1)$ such that, for arbitrarily larg…

math.CO2026

On the threshold Ramsey multiplicity conjectures for paths and even cycles

Ting Huang, Jiabao Yang, Yaojun Chen

The Ramsey number $r (H)$ of a graph $H$ is the minimum positive integer $n$ such that every red/blue edge-coloring of the complete graph $K_{n}$ on $n$ vertices contains a monochroma…

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…

Any k-graph with zero ℓ-degree Turán density is layered

On the codegree Turán density of projective geometries

On linear k-graphs with codegree Turán density arbitrarily close to zero

On the threshold Ramsey multiplicity conjectures for paths and even cycles

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

New bounds for Ramsey numbers involving graphs with a center

Any $k$ -graph with zero $ℓ$ -degree Turán density is layered

On linear $k$ -graphs with codegree Turán density arbitrarily close to zero