1. On depth of modules in an ideal.
- Author
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An, Tran Nguyen
- Subjects
- *
FINITE rings , *NOETHERIAN rings , *LOCAL rings (Algebra) , *QUOTIENT rings , *COMMUTATIVE rings - Abstract
Let R be a commutative Noetherian ring, I an ideal of R and M a finitely generated
R -module with dimR (M ) =d . Denote by depthR(I,M) the depth of M in I. In [C. Huneke and V. Trivedi, The height of ideals and regular sequences,Manuscr. Math .93 (1997) 137–142], Huneke and Trivedi proved that if R is a quotient of a regular ring then there exists a finite subset ΛM of Spec(R) such that depthR(I,M) =min픭∈Λ M{depthR픭(M픭) + ht((I + 픭)/픭)}. Denote by PsuppRi(M) = {픭 ∈Spec(R)|H픭 R픭i−dim(R/픭)(M픭)≠0} the ith pseudo support of M defined by Brodmann and Sharp [On the dimension and multiplicity of local cohomology modules,Nagoya Math. J. 167 (2002) 217–233]. In this paper, we prove that if PsuppRi(M) is closed for all i ≤ d then the above formula of depthR(I,M) holds true, where ΛM =⋃0≤i≤dmin PsuppRi(M). In particular, if R is a quotient of a Cohen–Macaulay local ring then ΛM = ⋃0≤i≤dminVar(AnnR(H픪i(M))). We also give some examples to clarify the results. [ABSTRACT FROM AUTHOR]- Published
- 2024
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