Jia-Bao Yang

collaborators

11 papers

math.CO2026

Coordinate-extension degrees and layered $k$ -uniform hypergraphs

Jiabao Yang

Let $\Palt=(\C,\T)$ be a $k$ -palette. For $0 \leq t \leq k - 1$ , its $t$ th coordinate-extension degree is the minimum, over every choice of $t$ coordinates and every assignment of colors…

math.CO2026

Ramsey multiplicity and extremal colorings for odd cycles

Ting Huang, Junying Lu, Jiabao Yang +1

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

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

New upper bound for the Ramsey number of odd cycles

Ting Huang, Jiabao Yang, Yaojun Chen

The \emph{ $k$ -color Ramsey number} $R_{k} (C_{2 ℓ + 1})$ is the least integer $n$ such that any $k$ -edge-coloring of a complete graph $K_{n}$ has a monochromatic odd cycle $C_{2 ℓ + 1}$ …

math.CO2026

Proofs of two conjectures on generalizations of Brouwer's Laplacian conjecture

Junying Lu, Jiabao Yang

Let $G = (V, E)$ be a simple graph of order $n$ and let $λ_{1} (G) \geq \dots \geq λ_{n} (G)$ be the eigenvalues of its Laplacian matrix. Brouwer conjectured that for every $1 \leq k \leq n$ , $\s…

math.CO2026

Odd covers for complete graphs and complete 3-graphs

Ting Huang, Jiabao Yang, Yaojun Chen

The Graham-Pollak theorem says that one needs at least $n - 1$ complete bipartite graphs to cover each edge of a complete graph $K_{n}$ on $n$ vertices exactly once. The odd cover…

math.CO2026

Further Results on the Maximum Number of Stars in Graphs with Forbidden Properties

Yuxuan Liu, Jia-Bao Yang, Leilei Zhang

A graph $G$ is called $k$ -edge-hamiltonian if every linear forest (i.e., a disjoint union of paths) with at most $k$ edges is contained in a Hamilton cycle of $G$ . In 2018, Füredi,…

math.CO2026

Counterexamples to the Balogh-Linz-Patkós Conjecture

Jia-Bao Yang, Leilei Zhang

A set system $F$ is called $t$ -intersecting if $∣ A \cap B ∣ \geq t$ for every pair of sets $A, B \in F .$ A set system $F$ is $k$ -Sperner if it does not cont…

math.CO2026

On the distinct maximal-clique sizes in $k$ -uniform hypergraphs

Jiabao Yang, Lixiang Yu, Leilei Zhang

Let $g (n, k)$ be the maximum number of distinct sizes of maximal cliques in an $n$ -vertex $k$ -uniform hypergraph, and let $f (n, k) = n - g (n, k)$ . We determine the asymptotic order of $f(…

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

The maximum number of triangles in graphs without vertex disjoint friendship graphs

Wanfang Chen, Jia-Bao Yang, Leilei Zhang

Given graphs $H$ and $F$ , the generalized Turán number $ex (n, H, F)$ is the maximum number of copies of $H$ among all $n$ -vertex $F$ -free graphs. The friendship graph $F_{k}$ …

Coordinate-extension degrees and layered k-uniform hypergraphs

Ramsey multiplicity and extremal colorings for odd cycles

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

New upper bound for the Ramsey number of odd cycles

Proofs of two conjectures on generalizations of Brouwer's Laplacian conjecture

Odd covers for complete graphs and complete 3-graphs

Further Results on the Maximum Number of Stars in Graphs with Forbidden Properties

Counterexamples to the Balogh-Linz-Patkós Conjecture

On the distinct maximal-clique sizes in k-uniform hypergraphs

On the threshold Ramsey multiplicity conjectures for paths and even cycles

The maximum number of triangles in graphs without vertex disjoint friendship graphs

Coordinate-extension degrees and layered $k$ -uniform hypergraphs

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

On the distinct maximal-clique sizes in $k$ -uniform hypergraphs