Torsion-free Modules over Commutative Domains of Krull Dimension One

Fuente: arXiv
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Hauptverfasser: Álvarez, Román, Herbera, Dolors, Příhoda, Pavel
Format: Preprint
Veröffentlicht: 2024
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author Álvarez, Román
Herbera, Dolors
Příhoda, Pavel
author_facet Álvarez, Román
Herbera, Dolors
Příhoda, Pavel
contents Let $R$ be a domain of Krull dimension one, we study when the class $\mathcal{F}$ of modules over $R$ that are arbitrary direct sums of finitely generated torsion-free modules is closed under direct summands. If $R$ is local, we show that $\mathcal{F}$ is closed under direct summands if and only if any indecomposable, finitely generated, torsion-free module has local endomorphism ring. If, in addition, $R$ is noetherian this is equivalent to say that the normalization of $R$ is a local ring. If $R$ is an $h$-local domain of Krull dimension $1$ and $\mathcal{F}_R$ is closed under direct summands, then the property is inherited by the localizations of $R$ at maximal ideals. Moreover, any localizations of $R$ at a maximal ideal, except maybe one, satisfies that any finitely generated ideal is $2$-generated. The converse is true when the domain $R$ is, in addition, integrally closed, or noetherian semilocal or noetherian with module-finite normalization. Finally, over a commutative domain of finite character and with no restriction on the Krull dimension, we show that the isomorphism classes of countable generated modules in $\mathcal{F}$ are determined by their genus.
format Preprint
id arxiv_https___arxiv_org_abs_2406_14665
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Torsion-free Modules over Commutative Domains of Krull Dimension One
Álvarez, Román
Herbera, Dolors
Příhoda, Pavel
Commutative Algebra
Rings and Algebras
13C60, 13G05, 16D70
Let $R$ be a domain of Krull dimension one, we study when the class $\mathcal{F}$ of modules over $R$ that are arbitrary direct sums of finitely generated torsion-free modules is closed under direct summands. If $R$ is local, we show that $\mathcal{F}$ is closed under direct summands if and only if any indecomposable, finitely generated, torsion-free module has local endomorphism ring. If, in addition, $R$ is noetherian this is equivalent to say that the normalization of $R$ is a local ring. If $R$ is an $h$-local domain of Krull dimension $1$ and $\mathcal{F}_R$ is closed under direct summands, then the property is inherited by the localizations of $R$ at maximal ideals. Moreover, any localizations of $R$ at a maximal ideal, except maybe one, satisfies that any finitely generated ideal is $2$-generated. The converse is true when the domain $R$ is, in addition, integrally closed, or noetherian semilocal or noetherian with module-finite normalization. Finally, over a commutative domain of finite character and with no restriction on the Krull dimension, we show that the isomorphism classes of countable generated modules in $\mathcal{F}$ are determined by their genus.
title Torsion-free Modules over Commutative Domains of Krull Dimension One
topic Commutative Algebra
Rings and Algebras
13C60, 13G05, 16D70
url https://arxiv.org/abs/2406.14665