Chordal graphs with bounded tree-width

Fuente: arXiv
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Main Authors: Castellví, Jordi, Drmota, Michael, Noy, Marc, Requilé, Clément
Format: Preprint
Published: 2022
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author Castellví, Jordi
Drmota, Michael
Noy, Marc
Requilé, Clément
author_facet Castellví, Jordi
Drmota, Michael
Noy, Marc
Requilé, Clément
contents Given $t\geq 2$ and $0\leq k\leq t$, we prove that the number of labelled $k$-connected chordal graphs with $n$ vertices and tree-width at most $t$ is asymptotically $c n^{-5/2} γ^n n!$, as $n\to\infty$, for some constants $c,γ>0$ depending on $t$ and $k$. Additionally, we show that the number of $i$-cliques ($2\leq i\leq t$) in a uniform random $k$-connected chordal graph with tree-width at most $t$ is normally distributed as $n\to\infty$. The asymptotic enumeration of graphs of tree-width at most $t$ is wide open for $t\geq 3$. To the best of our knowledge, this is the first non-trivial class of graphs with bounded tree-width where the asymptotic counting problem is solved. Our starting point is the work of Wormald [Counting Labelled Chordal Graphs, Graphs and Combinatorics (1985)], were an algorithm is developed to obtain the exact number of labelled chordal graphs on $n$ vertices.
format Preprint
id arxiv_https___arxiv_org_abs_2301_00194
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle Chordal graphs with bounded tree-width
Castellví, Jordi
Drmota, Michael
Noy, Marc
Requilé, Clément
Combinatorics
05C30
Given $t\geq 2$ and $0\leq k\leq t$, we prove that the number of labelled $k$-connected chordal graphs with $n$ vertices and tree-width at most $t$ is asymptotically $c n^{-5/2} γ^n n!$, as $n\to\infty$, for some constants $c,γ>0$ depending on $t$ and $k$. Additionally, we show that the number of $i$-cliques ($2\leq i\leq t$) in a uniform random $k$-connected chordal graph with tree-width at most $t$ is normally distributed as $n\to\infty$. The asymptotic enumeration of graphs of tree-width at most $t$ is wide open for $t\geq 3$. To the best of our knowledge, this is the first non-trivial class of graphs with bounded tree-width where the asymptotic counting problem is solved. Our starting point is the work of Wormald [Counting Labelled Chordal Graphs, Graphs and Combinatorics (1985)], were an algorithm is developed to obtain the exact number of labelled chordal graphs on $n$ vertices.
title Chordal graphs with bounded tree-width
topic Combinatorics
05C30
url https://arxiv.org/abs/2301.00194