Spectral Theory of the Toroidal 3D Queen Graph

Fuente: arXiv
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Main Author: Ramani, Mahesh
Format: Preprint
Published: 2026
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author Ramani, Mahesh
author_facet Ramani, Mahesh
contents We study the adjacency spectrum of the toroidal three-dimensional queen graph $G_n$ on $(\mathbb{Z}_n)^3$. Since $G_n$ is a Cayley graph on an abelian group, its adjacency matrix is diagonalized by Fourier characters. For each frequency $a\in(\mathbb{Z}_n)^3$, the corresponding eigenvalue is $λ(a)=nμ(a)-13$, where $μ(a)$ counts the queen directions orthogonal to $a$ modulo $n$. In the generic odd case, meaning $n$ odd with $3\nmid n$, the possible values of $μ(a)$ are exactly $0,1,2,3,4,$ and $13$, and each multiplicity is given by an explicit polynomial in $n$. The proof combines a geometric classification of frequency points by orthogonality type with two global counting identities.
format Preprint
id arxiv_https___arxiv_org_abs_2604_03842
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Spectral Theory of the Toroidal 3D Queen Graph
Ramani, Mahesh
Combinatorics
Spectral Theory
05C50, 05C25
We study the adjacency spectrum of the toroidal three-dimensional queen graph $G_n$ on $(\mathbb{Z}_n)^3$. Since $G_n$ is a Cayley graph on an abelian group, its adjacency matrix is diagonalized by Fourier characters. For each frequency $a\in(\mathbb{Z}_n)^3$, the corresponding eigenvalue is $λ(a)=nμ(a)-13$, where $μ(a)$ counts the queen directions orthogonal to $a$ modulo $n$. In the generic odd case, meaning $n$ odd with $3\nmid n$, the possible values of $μ(a)$ are exactly $0,1,2,3,4,$ and $13$, and each multiplicity is given by an explicit polynomial in $n$. The proof combines a geometric classification of frequency points by orthogonality type with two global counting identities.
title Spectral Theory of the Toroidal 3D Queen Graph
topic Combinatorics
Spectral Theory
05C50, 05C25
url https://arxiv.org/abs/2604.03842