The multi-level friendship paradox for sparse random graphs

Fuente: arXiv
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Autores principales: Hazra, Rajat Subhra, Hollander, Frank den, Parvaneh, Azadeh
Formato: Preprint
Publicado: 2025
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author Hazra, Rajat Subhra
Hollander, Frank den
Parvaneh, Azadeh
author_facet Hazra, Rajat Subhra
Hollander, Frank den
Parvaneh, Azadeh
contents In Hazra, den Hollander and Parvaneh (2025) we analysed the friendship paradox for sparse random graphs. For four classes of random graphs we characterised the empirical distribution of the friendship biases between vertices and their neighbours at distance $1$, proving convergence as $n\to\infty$ to a limiting distribution, with $n$ the number of vertices, and identifying moments and tail exponents of the limiting distribution. In the present paper we look at the multi-level friendship bias between vertices and their neighbours at distance $k \in \mathbb{N}$ obtained via a $k$-step exploration according to a backtracking or a non-backtracking random walk. We identify the limit of empirical distribution of the multi-level friendship biases as $n\to\infty$ and/or $k\to\infty$. We show that for non-backtracking exploration the two limits commute for a large class of sparse random graphs, including those that locally converge to a rooted Galton-Watson tree. In particular, we show that the same limit arises when $k$ depends on $n$, i.e., $k=k_n$, provided $\lim_{n\to\infty} k_n = \infty$ under some mild conditions. We exhibit cases where the two limits do not commute and show the relevance of the mixing time of the exploration.
format Preprint
id arxiv_https___arxiv_org_abs_2502_17724
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The multi-level friendship paradox for sparse random graphs
Hazra, Rajat Subhra
Hollander, Frank den
Parvaneh, Azadeh
Probability
05C80, 60C05, 60F15, 60J80, 60G50
In Hazra, den Hollander and Parvaneh (2025) we analysed the friendship paradox for sparse random graphs. For four classes of random graphs we characterised the empirical distribution of the friendship biases between vertices and their neighbours at distance $1$, proving convergence as $n\to\infty$ to a limiting distribution, with $n$ the number of vertices, and identifying moments and tail exponents of the limiting distribution. In the present paper we look at the multi-level friendship bias between vertices and their neighbours at distance $k \in \mathbb{N}$ obtained via a $k$-step exploration according to a backtracking or a non-backtracking random walk. We identify the limit of empirical distribution of the multi-level friendship biases as $n\to\infty$ and/or $k\to\infty$. We show that for non-backtracking exploration the two limits commute for a large class of sparse random graphs, including those that locally converge to a rooted Galton-Watson tree. In particular, we show that the same limit arises when $k$ depends on $n$, i.e., $k=k_n$, provided $\lim_{n\to\infty} k_n = \infty$ under some mild conditions. We exhibit cases where the two limits do not commute and show the relevance of the mixing time of the exploration.
title The multi-level friendship paradox for sparse random graphs
topic Probability
05C80, 60C05, 60F15, 60J80, 60G50
url https://arxiv.org/abs/2502.17724