English

Cofiniteness of local cohomology modules for ideals of dimension one

Commutative Algebra 2013-08-29 v1

Abstract

Let RR denote a commutative Noetherian (not necessarily local) ring, MM an arbitrary RR-module and II an ideal of RR of dimension one. It is shown that the RR-module \ExtRi(R/I,M)\Ext^i_R(R/I,M) is finitely generated (resp. weakly Laskerian) for all icd(I,M)+1i\leq {\rm cd}(I,M)+1 if and only if the local cohomology module HIi(M)H^i_I(M) is II-cofinite (resp. II-weakly cofinite) for all ii. Also, we show that when II is an arbitrary ideal and MM is finitely generated module such that the RR-module HIi(M)H^i_I(M) is weakly Laskerian for all it1i\leq t-1, then HIi(M)H^i_I(M) is II-cofinite for all it1i\leq t-1 and for any minimax submodule KK of HIt(M)H^{t}_I(M), the RR-modules \HomR(R/I,HIt(M)/K)\Hom_R(R/I, H^{t}_I(M)/K) and \ExtR1(R/I,HIt(M)/K)\Ext^{1}_R(R/I, H^{t}_I(M)/K) are finitely generated, where tt is a non-negative integer. This generalizes the main result of Bahmanpour-Naghipour \cite{BN} and Brodmann and Lashgari \cite{BL}.

Keywords

Cite

@article{arxiv.1308.6040,
  title  = {Cofiniteness of local cohomology modules for ideals of dimension one},
  author = {Kamal Bahmanpour and Reza Naghipour and Monireh Sedghi},
  journal= {arXiv preprint arXiv:1308.6040},
  year   = {2013}
}

Comments

7 pages