Fluctuations of functions of sparse Erd\H{o}s-R\'enyi graphs

TL;DR

This paper investigates the fluctuations of functions of the adjacency matrix in sparse Erdős-Rényi graphs, revealing a phase transition in the distribution of diagonal entries across spectral scales.

Contribution

It characterizes the asymptotic distribution of matrix function entries in sparse graphs and identifies a phase transition phenomenon.

Findings

Distribution of $f(A)_{ii}$ is asymptotically Gaussian.

Two independent Gaussian components on different scales.

Phase transition in fluctuation behavior at certain spectral scales.

Abstract

Let $A$ be the (rescaled) adjacency matrix of the Erd\H{o}s-R\'enyi graphs $\cal G(N,p)$. For $N^{-1+\tau} \leqslant p\leqslant N^{-\tau}$, we study the fluctuation of $f(A)_{ii}$ on the global and mesoscopic spectral scales. We show that the distribution of $f(A)_{ii}$ is asymptotically the sum of two independent Gaussian random variables on different scales, where a phase transition occurs on the spectral scale $p$.