Computing the unit group of a commutative finite $\mathbb{Z}$-algebra

Fuente: arXiv
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Hauptverfasser: Kreuzer, Martin, Walsh, Florian
Format: Preprint
Veröffentlicht: 2024
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author Kreuzer, Martin
Walsh, Florian
author_facet Kreuzer, Martin
Walsh, Florian
contents For a commutative finite $\mathbb{Z}$-algebra, i.e., for a commutative ring $R$ whose additive group is finitely generated, it is known that the group of units of $R$ is finitely generated, as well. Our main results are algorithms to compute generators and the structure of this group. This is achieved by reducing the task first to the case of reduced rings, then to torsion-free reduced rings, and finally to an order in a reduced ring. The simplified cases are treated via a calculation of exponent lattices and various algorithms to compute the minimal primes, primitive idempotents, and other basic objects. All algorithms have been implemented and are available as a SageMath package. Whenever possible, the time complexity of the described methods is tracked carefully.
format Preprint
id arxiv_https___arxiv_org_abs_2405_07002
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Computing the unit group of a commutative finite $\mathbb{Z}$-algebra
Kreuzer, Martin
Walsh, Florian
Commutative Algebra
Group Theory
Rings and Algebras
68W30 (Primary) 20F05 13P99 16Z05 (Secondary)
For a commutative finite $\mathbb{Z}$-algebra, i.e., for a commutative ring $R$ whose additive group is finitely generated, it is known that the group of units of $R$ is finitely generated, as well. Our main results are algorithms to compute generators and the structure of this group. This is achieved by reducing the task first to the case of reduced rings, then to torsion-free reduced rings, and finally to an order in a reduced ring. The simplified cases are treated via a calculation of exponent lattices and various algorithms to compute the minimal primes, primitive idempotents, and other basic objects. All algorithms have been implemented and are available as a SageMath package. Whenever possible, the time complexity of the described methods is tracked carefully.
title Computing the unit group of a commutative finite $\mathbb{Z}$-algebra
topic Commutative Algebra
Group Theory
Rings and Algebras
68W30 (Primary) 20F05 13P99 16Z05 (Secondary)
url https://arxiv.org/abs/2405.07002