5 papers
Supersaturation in Nosal graphs: Triangles and books
Hongzhang Chen, Yongtao Li, Quanyu Tang
In this paper, we use the spectral surplus to measure how far lies above the Nosal threshold, and prove the following edge-spectral supersaturation results fo…
An edge-spectral supersaturation of Mubayi's theorem for color-critical graphs
Hongzhang Chen, Yongtao Li
We study the supersaturation problem in its edge-spectral form. Let be the adjacency spectral radius of . Nikiforov proved that every -free graph with ed…
Spectral extremal graphs for even factors
Zeyuan Wu, Hongzhang Chen, Xinting Shi +1
An even factor of a graph is a spanning subgraph in which every vertex has positive even degree. It is known that the minimum degree is a trivial necessary conditio…
On a conjecture of distance spectral extremal problems
Hongzhang Chen, Jianxi Li, Yongtao Li
Brualdi and Hoffman proposed a well-known problem of determining the graph with maximum adjacency spectral radius among all graphs with given size . Early work by Friedland and…
An exponentially small gap of the Perron vector on independent sets
Hongzhang Chen, Jianxi Li, Yongtao Li +2
A classical result of Cioabă states that if is a connected graph with the unit Perron vector , then any independent set of satisfies $\sum_{v\in S} x_v^2 \l…