Sharp isoperimetric inequalities for infinite plane graphs with bounded vertex and face degrees

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Auteur principal: Oh, Byung-Geun
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Publié: 2020
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author Oh, Byung-Geun
author_facet Oh, Byung-Geun
contents We provide sharp bounds for the isoperimetric constants of infinite plane graphs (tessellations) with bounded vertex and face degrees. For example, if $G$ is a plane graph satisfying the inequalities $p_1 \leq \mbox{deg}\ v \leq p_2$ for $v \in V(G)$ and $q_1 \leq \mbox{deg}\ f \leq q_2$ for $f \in F(G)$, where $p_1, p_2, q_1$, and $q_2$ are natural numbers such that $1/p_i + 1/q_i \leq 1/2$, $i=1,2$, then we show that \[ Φ(p_1, q_1) \leq \inf_S \frac{|\partial S|}{|V(S)|} \leq Φ(p_2, q_2), \] where the infimum is taken over all finite nonempty subgraphs $S \subset G$, $\partial S$ is the set of edges connecting $S$ to $G \setminus S$, and $Φ(p,q)$ is defined by \[ Φ(p, q) = (p-2) \sqrt{1 - \frac{4}{(p-2)(q-2)}}. \] For $p_1=3$ this gives an affirmative answer to a conjecture by Lawrencenko, Plummer, and Zha from 2002, and for general $p_i$ and $q_i$ our result fully resolves a question posed in the book by Lyons and Peres from 2016, where they extended the conjecture of Lawrencenko et al. to the above form.
format Preprint
id arxiv_https___arxiv_org_abs_2009_04394
institution arXiv
publishDate 2020
record_format arxiv
spellingShingle Sharp isoperimetric inequalities for infinite plane graphs with bounded vertex and face degrees
Oh, Byung-Geun
Combinatorics
Metric Geometry
05C10, 05B45, 05C63, 52C20
We provide sharp bounds for the isoperimetric constants of infinite plane graphs (tessellations) with bounded vertex and face degrees. For example, if $G$ is a plane graph satisfying the inequalities $p_1 \leq \mbox{deg}\ v \leq p_2$ for $v \in V(G)$ and $q_1 \leq \mbox{deg}\ f \leq q_2$ for $f \in F(G)$, where $p_1, p_2, q_1$, and $q_2$ are natural numbers such that $1/p_i + 1/q_i \leq 1/2$, $i=1,2$, then we show that \[ Φ(p_1, q_1) \leq \inf_S \frac{|\partial S|}{|V(S)|} \leq Φ(p_2, q_2), \] where the infimum is taken over all finite nonempty subgraphs $S \subset G$, $\partial S$ is the set of edges connecting $S$ to $G \setminus S$, and $Φ(p,q)$ is defined by \[ Φ(p, q) = (p-2) \sqrt{1 - \frac{4}{(p-2)(q-2)}}. \] For $p_1=3$ this gives an affirmative answer to a conjecture by Lawrencenko, Plummer, and Zha from 2002, and for general $p_i$ and $q_i$ our result fully resolves a question posed in the book by Lyons and Peres from 2016, where they extended the conjecture of Lawrencenko et al. to the above form.
title Sharp isoperimetric inequalities for infinite plane graphs with bounded vertex and face degrees
topic Combinatorics
Metric Geometry
05C10, 05B45, 05C63, 52C20
url https://arxiv.org/abs/2009.04394