The first Steklov eigenvalue of planar graphs and beyond

Fuente: arXiv
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Auteurs principaux: Lin, Huiqiu, Zhao, Da
Format: Preprint
Publié: 2024
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author Lin, Huiqiu
Zhao, Da
author_facet Lin, Huiqiu
Zhao, Da
contents The Steklov eigenvalue problem was introduced over a century ago, and its discrete form attracted interest recently. Let $D$ and $δΩ$ be the maximum vertex degree and the set of vertices of degree one in a graph $\mathcal{G}$ respectively. Let $λ_2$ be the first (non-trivial) Steklov eigenvalue of $(\mathcal{G}, δΩ)$. In this paper, using the circle packing theorem and conformal mapping, we first show that $λ_2 \leq 8D / |δΩ|$ for planar graphs. This can be seen as a discrete analogue of Kokarev's bound, that is, $λ_2 < 8π/ |\partial Ω|$ for compact surfaces with boundary of genus $0$. Let $B$ and $L$ be the maximum block size and the diameter of a block graph $\mathcal{G}$ respectively. Secondly, we prove that $λ_2 \leq 4 (B-1) (D-1)/ |δΩ|$ and $λ_2 \leq B/L$ for block graphs, which extend the results on trees by He and Hua. In the end, for trees with fixed leaf number and maximum degree, candidates that achieve the maximum first Steklov eigenvalue are given.
format Preprint
id arxiv_https___arxiv_org_abs_2407_08301
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle The first Steklov eigenvalue of planar graphs and beyond
Lin, Huiqiu
Zhao, Da
Combinatorics
47A75, 49J40, 49R05, 05C10
The Steklov eigenvalue problem was introduced over a century ago, and its discrete form attracted interest recently. Let $D$ and $δΩ$ be the maximum vertex degree and the set of vertices of degree one in a graph $\mathcal{G}$ respectively. Let $λ_2$ be the first (non-trivial) Steklov eigenvalue of $(\mathcal{G}, δΩ)$. In this paper, using the circle packing theorem and conformal mapping, we first show that $λ_2 \leq 8D / |δΩ|$ for planar graphs. This can be seen as a discrete analogue of Kokarev's bound, that is, $λ_2 < 8π/ |\partial Ω|$ for compact surfaces with boundary of genus $0$. Let $B$ and $L$ be the maximum block size and the diameter of a block graph $\mathcal{G}$ respectively. Secondly, we prove that $λ_2 \leq 4 (B-1) (D-1)/ |δΩ|$ and $λ_2 \leq B/L$ for block graphs, which extend the results on trees by He and Hua. In the end, for trees with fixed leaf number and maximum degree, candidates that achieve the maximum first Steklov eigenvalue are given.
title The first Steklov eigenvalue of planar graphs and beyond
topic Combinatorics
47A75, 49J40, 49R05, 05C10
url https://arxiv.org/abs/2407.08301