Zhao Da

collaborators

3 papers

math.CO2025

Almost all graphs have no cospectral mate with fixed level

Wei Wang, Da Zhao

Haemers conjectures that almost all graphs are determined by their spectra. Suppose $G \sim G (n, p)$ is a random graph with each edge chosen independently with probabilit…

math.CO2024

Upper bounds of Steklov eigenvalues on graphs

Huiqiu Lin, Lianping Liu, Zhe You +1

Let $Δ$ and $B$ be the maximum vertex degree and a subset of vertices in a graph $G$ respectively. In this paper, we study the first (non-trivial) Steklov eigenvalue $σ_{2}$ of $G$ w…

math.CO2024

Bivariate $Q$ -polynomial structures for the nonbinary Johnson scheme and the association scheme obtained from attenuated spaces

Eiichi Bannai, Hirotake Kurihara, Da Zhao +1

The study of $P$ -polynomial association schemes (distance-regular graphs) and $Q$ -polynomial association schemes, and in particular $P$ - and $Q$ -polynomial association schemes, has…

Almost all graphs have no cospectral mate with fixed level

Upper bounds of Steklov eigenvalues on graphs

Bivariate Q-polynomial structures for the nonbinary Johnson scheme and the association scheme obtained from attenuated spaces

Bivariate $Q$ -polynomial structures for the nonbinary Johnson scheme and the association scheme obtained from attenuated spaces