Yuejian Peng

activity

20092023

most citedThe spectral radius of graphs with no intersecting odd cycles

44 citations · 172 across the 37 of their papers we have counts for

collaborators

37 papers

math.CO2023★ 1 cited

Non-empty pairwise cross-intersecting families

Yang Huang, Yuejian Peng

Two families $A$ and $B$ are cross-intersecting if $A \cap B \neq = \emptyset$ for any $A \in A$ and $B \in B$ . We call $t$ families $\mathcal{A}_1…

math.CO2023★ 4 cited

Tight bound on the minimum degree to guarantee graphs forbidding some odd cycles to be bipartite

Xiaoli Yuan, Yuejian Peng

Erdős and Simonovits asked the following question: For an integer $r \geq 2$ and a family of non-bipartite graphs $H$ , determine the infimum of $α$ such that any $\mathcal…

math.CO2023★ 1 cited

Monochromatic cycles in 2-edge-colored bipartite graphs with large minimum degree

Yiran Zhang, Yuejian Peng

For graphs $G_{0}$ , $G_{1}$ and $G_{2}$ , write $G_{0} ⟼ (G_{1}, G_{2})$ if each red-blue-edge-coloring of $G_{0}$ yields a red $G_{1}$ or a blue $G_{2}$ . The Ramsey number $r (G_{1}, G_{2})$ is t…

math.CO2023★ 12 cited

A spectral extremal problem on non-bipartite triangle-free graphs

Yongtao Li, Lihua Feng, Yuejian Peng

A theorem of Nosal and Nikiforov states that if $G$ is a triangle-free graph with $m$ edges, then $λ (G) \leq m$ , where the equality holds if and only if $G$ is a complete bipa…

math.CO2022★ 29 cited

Spectral extremal graphs for the bowtie

Yongtao Li, Lu Lu, Yuejian Peng

Let $F_{k}$ be the (friendship) graph obtained from $k$ triangles by sharing a common vertex. The $F_{k}$ -free graphs of order $n$ which attain the maximal spectral radius was firstly…

math.CO2022

Lagrangian densities of some $3$ -uniform hypergraphs

Zilong Yan, Yuejian Peng

The Lagrangian density of an $r$ -uniform hypergraph $H$ is $r!$ multiplying the supremum of the Lagrangians of all $H$ -free $r$ -uniform hypergraphs. For an $r$ -uniform graph $H$ wi…

math.CO2022

Stability of intersecting families

Yang Huang, Yuejian Peng

The celebrated Erdős-Ko-Rado theorem \cite{EKR1961} states that the maximum intersecting $k$ -uniform family on $[n]$ is a full star if $n \geq 2 k + 1$ . Furthermore, Hilton-Milner \cite…

math.CO2022★ 21 cited

The maximum spectral radius of non-bipartite graphs forbidding short odd cycles

Yongtao Li, Yuejian Peng

It is well-known that eigenvalues of graphs can be used to describe structural properties and parameters of graphs. A theorem of Nosal states that if $G$ is a triangle-free graph w…

math.CO2022★ 18 cited

Refinement on spectral Turán's theorem

Yongtao Li, Yuejian Peng

A well-known result in extremal spectral graph theory, due to Nosal and Nikiforov, states that if $G$ is a triangle-free graph on $n$ vertices, then $λ(G) \le λ(K_{\lfloor \frac{n}…

math.CO2022★ 1 cited

New proofs of stability theorems on spectral graph problems

Yongtao Li, Yuejian Peng

Both the Simonovits stability theorem and the Nikiforov spectral stability theorem are powerful tools for solving exact values of Turán numbers in extremal graph theory. Recently,…

math.CO2022

The Ramsey Number for a Forest versus Disjoint Union of Complete Graphs

Sinan Hu, Yuejian Peng

Given two graphs $G$ and $H$ , the Ramsey number $R (G, H)$ is the minimum integer $N$ such that any coloring of the edges of $K_{N}$ in red or blue yields a red $G$ or a blue $H$ . Let…

math.CO2021

Tree Embeddings and Tree-Star Ramsey Numbers

Zilong Yan, Yuejian Peng

We say that a graph $F$ can be embedded into a graph $G$ if $G$ contains an isomorphic copy of $F$ as a subgraph. Guo and Volkmann \cite{GV} conjectured that if $G$ is a connected…

math.CO2021

Non-jumping Turán densities of hypergraphs

Zilong Yan, Yuejian Peng

A real number $α \in [0, 1)$ is a jump for an integer $r \geq 2$ if there exists $c > 0$ such that no number in $(α, α + c)$ can be the Turán density of a family of $r$ -uniform graphs. A…

math.CO2021

An irrational Lagrangian density of a single hypergraph

Zilong Yan, Yuejian Peng

The {\em Turán number} of an $r$ -uniform graph $F$ , denoted by $e x (n, F)$ , is the maximum number of edges in an $F$ -free $r$ -uniform graph on $n$ vertices. The {\em Turán density} o…

math.CO2021

The bipartite Ramsey number $b r (C_{2 n}, C_{2 m})$

Zilong Yan, Yuejian Peng

Given bipartite graphs $H_{1}$ , \dots , $H_{k}$ , the bipartite Ramsey number $b r (H_{1}, \dots, H_{k})$ is the minimum integer $N$ such that any $k$ -edge-coloring of complete bipartite graph…

math.FA2021★ 1 cited

An Oppenheim type inequality for positive definite block matrices

Yongtao Li, Yuejian Peng

We present an Oppenheim type determinantal inequality for positive definite block matrices. Recently, Lin [Linear Algebra Appl. 452 (2014) 1--6] proved a remarkable extension of Op…

math.CO2021★ 1 cited

Sufficient spectral conditions for graphs being $k$ -edge-Hamiltonian or $k$ -Hamiltonian

Yongtao Li, Yuejian Peng

A graph $G$ is $k$ -edge-Hamiltonian if any collection of vertex-disjoint paths with at most $k$ edges altogether belong to a Hamiltonian cycle in $G$ . A graph $G$ is $k$ -Hamiltonia…

math.CO2021★ 44 cited

The spectral radius of graphs with no intersecting odd cycles

Yongtao Li, Yuejian Peng

Let $H_{s, t_{1}, \dots, t_{k}}$ be the graph with $s$ triangles and $k$ odd cycles of lengths $t_{1}, \dots, t_{k} \geq 5$ intersecting in exactly one common vertex. Recently, Hou, Qiu and L…

math.CO2019

Lagrangian densities of short 3-uniform linear paths and Turán numbers of their extensions

Biao Wu, Yuejian Peng

For a fixed positive integer $n$ and an $r$ -uniform hypergraph $H$ , the Turán number $e x (n, H)$ is the maximum number of edges in an $H$ -free $r$ -uniform hypergraph on $n$ vertices,…

math.CO2018★ 4 cited

Lagrangian densities of hypergraph cycles

Yuejian Peng, Zilong Yan

The Lagrangian density of an $r$ -uniform hypergraph $F$ is $r!$ multiplying the supremum of the Lagrangians of all $F$ -free $r$ -uniform hypergraphs. For an $r$ -graph $H$ with $t$ v…

math.CO2018★ 1 cited

3-colored asymmetric bipartite Ramsey number of connected matchings and cycles

Zhidan Luo, Yuejian Peng

Let $k, l, m$ be integers and $r (k, l, m)$ be the minimum integer $N$ such that for any red-blue-green coloring of $K_{N, N}$ , there is a red matching of size at least $k$ in a componen…

math.CO2018★ 3 cited

Bipartite Ramsey numbers of large cycles

Shaoqiang Liu, Yuejian Peng

For an integer $r \geq 2$ and bipartite graphs $H_{i}$ , where $1 \leq i \leq r$ , the bipartite Ramsey number $b r (H_{1}, H_{2}, \dots, H_{r})$ is the minimum integer $N$ such that any $r$ -edge c…

math.CO2018★ 9 cited

On Lagrangians of $3$ -uniform hypergraphs

Hui Lei, Linyuan Lu, Yuejian Peng

Frankl and Füredi conjectured in 1989 that the maximum Lagrangian of all $r$ -uniform hypergraphs of fixed size $m$ is realized by the minimum hypergraph $C_{r, m}$ under the colexic…

math.CO2017★ 6 cited

On a conjecture of Hefetz and Keevash on Lagrangians of intersecting hypergraphs and Turán numbers

Biao Wu, Yuejian Peng, Pingge Chen

Let $S^{r} (n)$ be the $r$ -graph on $n$ vertices with parts $A$ and $B$ , where the edges consist of all $r$ -tuples with $1$ vertex in $A$ and $r - 1$ vertices in $B$ , and the sizes of $…

Non-empty pairwise cross-intersecting families

Tight bound on the minimum degree to guarantee graphs forbidding some odd cycles to be bipartite

Monochromatic cycles in 2-edge-colored bipartite graphs with large minimum degree

A spectral extremal problem on non-bipartite triangle-free graphs

Spectral extremal graphs for the bowtie

Lagrangian densities of some 3-uniform hypergraphs

Stability of intersecting families

The maximum spectral radius of non-bipartite graphs forbidding short odd cycles

Refinement on spectral Turán's theorem

New proofs of stability theorems on spectral graph problems

The Ramsey Number for a Forest versus Disjoint Union of Complete Graphs

Tree Embeddings and Tree-Star Ramsey Numbers

Non-jumping Turán densities of hypergraphs

An irrational Lagrangian density of a single hypergraph

The bipartite Ramsey number br(C2n​,C2m​)

An Oppenheim type inequality for positive definite block matrices

Sufficient spectral conditions for graphs being k-edge-Hamiltonian or k-Hamiltonian

The spectral radius of graphs with no intersecting odd cycles

Lagrangian densities of short 3-uniform linear paths and Turán numbers of their extensions

Lagrangian densities of hypergraph cycles

3-colored asymmetric bipartite Ramsey number of connected matchings and cycles

Bipartite Ramsey numbers of large cycles

On Lagrangians of 3-uniform hypergraphs

On a conjecture of Hefetz and Keevash on Lagrangians of intersecting hypergraphs and Turán numbers

Lagrangian densities of some $3$ -uniform hypergraphs

The bipartite Ramsey number $b r (C_{2 n}, C_{2 m})$

Sufficient spectral conditions for graphs being $k$ -edge-Hamiltonian or $k$ -Hamiltonian

On Lagrangians of $3$ -uniform hypergraphs