Subgraph probability of random graphs with specified degrees and applications to chromatic number and connectivity

Fuente: arXiv
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Autori principali: Gao, Pu, Ohapkin, Yuval
Natura: Preprint
Pubblicazione: 2020
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author Gao, Pu
Ohapkin, Yuval
author_facet Gao, Pu
Ohapkin, Yuval
contents Given a graphical degree sequence ${\bf d}=(d_1,\ldots, d_n)$, let $G(n, {\bf d})$ denote a uniformly random graph on vertex set $[n]$ where vertex $ i$ has degree $d_i$ for every $1\le i\le n$. We give upper and lower bounds on the joint probability of an arbitrary set of edges in $G(n,{\bf d})$. These upper and lower bounds are approximately what one would get in the configuration model, and thus the analysis in the configuration model can be translated directly to $G(n,{\bf d})$, without conditioning on that the configuration model produces a simple graph. Many existing results of $G(n,{\bf d})$ in the literature can be significantly improved with simpler proofs, by applying this new probabilistic tool. One example we give is about the chromatic number of $G(n,{\bf d})$. In another application, we use these joint probabilities to study the connectivity of $G(n,{\bf d})$. When $Δ^2=o(M)$ where $Δ$ is the maximum component of ${\bf d}$, we fully characterise the connectivity phase transition of $G(n,{\bf d})$. We also give sufficient conditions for $G(n,{\bf d})$ being connected when $Δ$ is unrestricted.
format Preprint
id arxiv_https___arxiv_org_abs_2007_02216
institution arXiv
publishDate 2020
record_format arxiv
spellingShingle Subgraph probability of random graphs with specified degrees and applications to chromatic number and connectivity
Gao, Pu
Ohapkin, Yuval
Combinatorics
05C80
Given a graphical degree sequence ${\bf d}=(d_1,\ldots, d_n)$, let $G(n, {\bf d})$ denote a uniformly random graph on vertex set $[n]$ where vertex $ i$ has degree $d_i$ for every $1\le i\le n$. We give upper and lower bounds on the joint probability of an arbitrary set of edges in $G(n,{\bf d})$. These upper and lower bounds are approximately what one would get in the configuration model, and thus the analysis in the configuration model can be translated directly to $G(n,{\bf d})$, without conditioning on that the configuration model produces a simple graph. Many existing results of $G(n,{\bf d})$ in the literature can be significantly improved with simpler proofs, by applying this new probabilistic tool. One example we give is about the chromatic number of $G(n,{\bf d})$. In another application, we use these joint probabilities to study the connectivity of $G(n,{\bf d})$. When $Δ^2=o(M)$ where $Δ$ is the maximum component of ${\bf d}$, we fully characterise the connectivity phase transition of $G(n,{\bf d})$. We also give sufficient conditions for $G(n,{\bf d})$ being connected when $Δ$ is unrestricted.
title Subgraph probability of random graphs with specified degrees and applications to chromatic number and connectivity
topic Combinatorics
05C80
url https://arxiv.org/abs/2007.02216