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Hauptverfasser: Aoki, Hiroki, Kawanoue, Hiraku
Format: Preprint
Veröffentlicht: 2025
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Online-Zugang:https://arxiv.org/abs/2503.03605
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author Aoki, Hiroki
Kawanoue, Hiraku
author_facet Aoki, Hiroki
Kawanoue, Hiraku
contents Root systems are sets with remarkable symmetries and therefore they appear in many situations in mathematics. Among others, denominator formulae of root systems are very beautiful and mysterious equations which have several meanings from a variety of disciplines in mathematics. In this paper, we show a converse statement of this phenomena. Namely, for a given finite subset $ S $ of a Euclidean vector space $ V $, define an equation $ F $ in the group ring $ {\mathbb{Z}}[V] $ featuring the product part of denominator formulae. Then, a geometric condition for the support of $ F $ characterizes $ S $ being a set of positive roots of a finite/affine root system, recovering the denominator formula. This gives a novel characterization of the sets of positive roots of reduced finite/affine root systems.
format Preprint
id arxiv_https___arxiv_org_abs_2503_03605
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle A characterization of root systems from the viewpoint of denominator formulae
Aoki, Hiroki
Kawanoue, Hiraku
Rings and Algebras
17B22
Root systems are sets with remarkable symmetries and therefore they appear in many situations in mathematics. Among others, denominator formulae of root systems are very beautiful and mysterious equations which have several meanings from a variety of disciplines in mathematics. In this paper, we show a converse statement of this phenomena. Namely, for a given finite subset $ S $ of a Euclidean vector space $ V $, define an equation $ F $ in the group ring $ {\mathbb{Z}}[V] $ featuring the product part of denominator formulae. Then, a geometric condition for the support of $ F $ characterizes $ S $ being a set of positive roots of a finite/affine root system, recovering the denominator formula. This gives a novel characterization of the sets of positive roots of reduced finite/affine root systems.
title A characterization of root systems from the viewpoint of denominator formulae
topic Rings and Algebras
17B22
url https://arxiv.org/abs/2503.03605