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JOURNALS // Zhurnal Matematicheskoi Fiziki, Analiza, Geometrii [Journal of Mathematical Physics, Analysis, Geometry] // Archive

Zh. Mat. Fiz. Anal. Geom., 2016 Volume 12, Number 1, Pages 78–93 (Mi jmag629)

Eigenvalue distribution of bipartite large weighted random graphs. Resolvent approach

V. Vengerovsky

B. Verkin Institute for Low Temperature Physics and Engineering, National Academy of Sciences of Ukraine, 47 Nauki Ave., Kharkiv, 61103, Ukraine

Abstract: We study an eigenvalue distribution of the adjacency matrix $A^{(N,p, \alpha)}$ of the weighted random bipartite graphs $\Gamma= \Gamma_{N,p,\alpha}$. We assume that the graphs have $N$ vertices, the ratio of parts is $\frac{\alpha}{1-\alpha}$, and the average number of edges attached to one vertex is $\alpha p$ for the first part and $(1-\alpha) p$ for the second part of vertices. To each edge of the graph $e_{ij}$, we assign the weight given by a random variable $a_{ij}$ with the finite second moment.
We consider the resolvents $G^{(N,p, \alpha)}(z)$ of $A^{(N,p, \alpha)}$ and study the functions
\begin{gather*}f_{1,N}(u,z)=\frac{1}{[\alpha N]}\sum_{k=1}^{[\alpha N]}e^{-ua_k^2G_{kk}^{(N,p,\alpha)}(z)} \end{gather*}
and
\begin{gather*}f_{2,N}(u,z)=\frac{1}{N-[\alpha N]}\sum_{k=[\alpha N]+1}^Ne^{-ua_k^2G_{kk}^{(N,p,\alpha)}(z)}\end{gather*}
in the limit $N\to \infty$. We derive a closed system of equations that uniquely determine the limiting functions $f_{1}(u,z)$ and $f_{2}(u,z)$. This system of equations allows us to prove the existence of the limiting measure $\sigma_{p, \alpha}$. The weak convergence in probability of the normalized eigenvalue counting measures is proved.

Key words and phrases: sparse random matrices, bipartite graphs, normalized eigenvalue counting measure.

MSC: 15B52

Received: 26.01.2015
Revised: 16.06.2015

Language: English

DOI: 10.15407/mag12.01.078



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