Classification of equiangular lines with fixed angle $\arccos(1/(1+2\sqrt2))$

Fuente: arXiv
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Main Authors: Gossett, Theodore, Jiang, Zilin, Teets, Adam, Wellner, Zoe
Format: Preprint
Published: 2026
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author Gossett, Theodore
Jiang, Zilin
Teets, Adam
Wellner, Zoe
author_facet Gossett, Theodore
Jiang, Zilin
Teets, Adam
Wellner, Zoe
contents We determine the maximum number $N_α(d)$ of equiangular lines with fixed angle $\arccosα$ for $α= 1/(1+2\sqrt2)$ in $d$-dimensional Euclidean space: $2,3,4,6,8,10,14,15,16,17,18,20,22$ for $d \in \{2,\dots,14\}$, and $\max(24, \lfloor 3(d-1)/2 \rfloor)$ for $d \ge 15$. This appears to be the first complete determination of $N_α(d)$ in all dimensions $d$ for a fixed nontrivial $α$, since the work of Lemmens and Seidel for $α= 1/3$ in 1973.
format Preprint
id arxiv_https___arxiv_org_abs_2603_02469
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Classification of equiangular lines with fixed angle $\arccos(1/(1+2\sqrt2))$
Gossett, Theodore
Jiang, Zilin
Teets, Adam
Wellner, Zoe
Combinatorics
Metric Geometry
05C50, 52C35
We determine the maximum number $N_α(d)$ of equiangular lines with fixed angle $\arccosα$ for $α= 1/(1+2\sqrt2)$ in $d$-dimensional Euclidean space: $2,3,4,6,8,10,14,15,16,17,18,20,22$ for $d \in \{2,\dots,14\}$, and $\max(24, \lfloor 3(d-1)/2 \rfloor)$ for $d \ge 15$. This appears to be the first complete determination of $N_α(d)$ in all dimensions $d$ for a fixed nontrivial $α$, since the work of Lemmens and Seidel for $α= 1/3$ in 1973.
title Classification of equiangular lines with fixed angle $\arccos(1/(1+2\sqrt2))$
topic Combinatorics
Metric Geometry
05C50, 52C35
url https://arxiv.org/abs/2603.02469