Roux schemes which carry association schemes locally

Fuente: arXiv
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Main Authors: Gavrilyuk, Alexander L., Lansdown, Jesse, Munemasa, Akihiro, Suda, Sho
Format: Preprint
Published: 2025
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author Gavrilyuk, Alexander L.
Lansdown, Jesse
Munemasa, Akihiro
Suda, Sho
author_facet Gavrilyuk, Alexander L.
Lansdown, Jesse
Munemasa, Akihiro
Suda, Sho
contents A roux scheme is an association scheme formed from a special "roux" matrix and the regular permutation representation of an associated group. They were introduced by Iverson and Mixon for their connection to equiangular tight frames and doubly transitive lines. We show how roux matrices can be produced from association schemes and characterise roux schemes for which the neighbourhood of a vertex induces an association scheme possessing the same number of relations as the thin radical. An important example arises from the $64$ equiangular lines in $\mathbb{C}^8$ constructed by Hoggar which we prove is unique (determined by its parameters up to isomorphism). We also characterise roux schemes by their eigenmatrices and provide new families of roux schemes using our construction.
format Preprint
id arxiv_https___arxiv_org_abs_2507_18960
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Roux schemes which carry association schemes locally
Gavrilyuk, Alexander L.
Lansdown, Jesse
Munemasa, Akihiro
Suda, Sho
Combinatorics
05E30, 05C50, 05E18
A roux scheme is an association scheme formed from a special "roux" matrix and the regular permutation representation of an associated group. They were introduced by Iverson and Mixon for their connection to equiangular tight frames and doubly transitive lines. We show how roux matrices can be produced from association schemes and characterise roux schemes for which the neighbourhood of a vertex induces an association scheme possessing the same number of relations as the thin radical. An important example arises from the $64$ equiangular lines in $\mathbb{C}^8$ constructed by Hoggar which we prove is unique (determined by its parameters up to isomorphism). We also characterise roux schemes by their eigenmatrices and provide new families of roux schemes using our construction.
title Roux schemes which carry association schemes locally
topic Combinatorics
05E30, 05C50, 05E18
url https://arxiv.org/abs/2507.18960