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On Ext-finite modules, quasi-injective dimension and width of modules

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Autor(es):
Jorge-Perez, V. H. ; Martins, Paulo
Número total de Autores: 2
Tipo de documento: Artigo Científico
Fonte: COMMUNICATIONS IN ALGEBRA; v. N/A, p. 9-pg., 2025-12-06.
Resumo

Let (R,m,k) be a commutative Noetherian local ring. It is well-known that if M is a finitely generated R-module of finite quasi-injective dimension, then qid(R)M=depth R. In this paper, we demonstrate that under the weaker condition that M is Ext-finite and has finite quasi-injective dimension, the equality qid(R)M=0 holds if and only if Ext(R)(i)>0(R/(x),M)=0, where x is an element of m is a maximal R-sequence and if qid(R)M not equal 0, we show then that qid(R)M=sup{i:Ext(R)(i)(R/(x),M)not equal 0}. Also, we show that if R is a Cohen-Macaulay local ring and M is an Ext-finite R-module of finite quasi-injective dimension, then depth R=qid(R)M+inf{i:Tor(i)(R)(k,M)not equal 0}, provided that inf{i:Tor(i)(R)(k,M)not equal 0}<infinity. (AU)

Processo FAPESP: 19/21181-0 - Novas fronteiras na Teoria de Singularidades
Beneficiário:Regilene Delazari dos Santos Oliveira
Modalidade de apoio: Auxílio à Pesquisa - Temático
Processo FAPESP: 22/12114-0 - Os funtores Tor e Ext: propriedades de anulamento e problemas relacionados
Beneficiário:Paulo Damião Christo Martins
Modalidade de apoio: Bolsas no Brasil - Doutorado