English

Hartshorne's questions and weakly cofiniteness

Commutative Algebra 2018-01-25 v1

Abstract

Let RR be a commutative Noetherian ring, \fa\fa be an ideal of RR and MM be an RR-module. The main purpose of this paper is to answer the Hartshorn's questions in the class of weakly Laskerian modules. It is shown that if s1s\geq 1 is a positive integer such that \ExtRj(R/\fa,M)\Ext^j_R(R/\fa, M) is weakly Laskerian for all jsj\leq s and the RR-module H\fai(M)H^i_\fa(M) is FD1FD_{\leq 1} for all i<si < s, then the RR-module H\fai(M)H^i_\fa(M) is \fa\fa-weakly cofinite for all i<si <s. In addition, we show that the category of all \fa\fa-weakly cofinite FD1FD_{\leq 1} RR-modules is an Abelian subcategory of the category of all RR-modules. Also, we prove that if \ExtRi(R/\fa,M)\Ext^i_R(R/\fa,M) is weakly Laskerian for all idimMi\leq \dim M, then the RR-module \ExtRi(N,M)\Ext^i_R(N,M) is weakly Laskerian for all i0i\geq 0 and for any finitely generated RR-module NN with \SuppR(N)V(\fa)\Supp_R(N) \subseteq V (\fa) and dimN1\dim N \leq 1.

Keywords

Cite

@article{arxiv.1801.07768,
  title  = {Hartshorne's questions and weakly cofiniteness},
  author = {Hajar Roshan-Shekalgourabi and Marzieh Hatamkhani},
  journal= {arXiv preprint arXiv:1801.07768},
  year   = {2018}
}
R2 v1 2026-06-22T23:53:37.974Z