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Main Authors: Gonzalez, Fulton, Nebeker, Adelaide, Hallett, Katie, Sailstad, Andew
Format: Preprint
Published: 2025
Subjects:
Online Access:https://arxiv.org/abs/2512.19136
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author Gonzalez, Fulton
Nebeker, Adelaide
Hallett, Katie
Sailstad, Andew
author_facet Gonzalez, Fulton
Nebeker, Adelaide
Hallett, Katie
Sailstad, Andew
contents By definition, a wave on a homogeneous tree $\mathfrak X$ is a solution to the discrete wave equation on $\mathfrak{X}$; that is, a family $\{f_k\}_{k\in\mathbb Z}$ of complex-valued functions on $\mathfrak X$ satisfying the partial difference equation $μ_1 f_k=(f_{k+1}+f_{k-1})/2$ for all $k$, where $μ_1$ is the mean value operator on $\mathfrak X$ of radius $1$. The function $f_k$ is called the snapshot of the wave at time $k$. For $k\geq 2$, we will show that there exist infinitely many waves having given snapshots at times $0$ and $k$, but that all such waves have the same snapshots at times which are multiples of $k$. For integers $0<k<\ell$, we then consider necessary and sufficient conditions for the existence and uniqueness of a wave with given snapshots at times $0,\,k,\,\ell$.
format Preprint
id arxiv_https___arxiv_org_abs_2512_19136
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The Snapshot Problem for Wave Equations on Homogeneous Trees
Gonzalez, Fulton
Nebeker, Adelaide
Hallett, Katie
Sailstad, Andew
Combinatorics
Primary: 43A85, Secondary: 39A14
By definition, a wave on a homogeneous tree $\mathfrak X$ is a solution to the discrete wave equation on $\mathfrak{X}$; that is, a family $\{f_k\}_{k\in\mathbb Z}$ of complex-valued functions on $\mathfrak X$ satisfying the partial difference equation $μ_1 f_k=(f_{k+1}+f_{k-1})/2$ for all $k$, where $μ_1$ is the mean value operator on $\mathfrak X$ of radius $1$. The function $f_k$ is called the snapshot of the wave at time $k$. For $k\geq 2$, we will show that there exist infinitely many waves having given snapshots at times $0$ and $k$, but that all such waves have the same snapshots at times which are multiples of $k$. For integers $0<k<\ell$, we then consider necessary and sufficient conditions for the existence and uniqueness of a wave with given snapshots at times $0,\,k,\,\ell$.
title The Snapshot Problem for Wave Equations on Homogeneous Trees
topic Combinatorics
Primary: 43A85, Secondary: 39A14
url https://arxiv.org/abs/2512.19136