English

On generalized completion homology modules

Commutative Algebra 2017-01-19 v2

Abstract

Let II be an ideal of a commutative Noetherian ring RR. Let MM and NN be any RR-modules. We define the generalized completion homology modules LiΛI(N,M)L_i\Lambda^I (N,M), for iZi\in \mathbb{Z}, as the homologies of the complex lim(N/IsNRFR)\lim\limits_{\longleftarrow}(N/I^sN\otimes_R F_{\cdot}^R). Here FRF_{\cdot}^R denote a flat resolution of MM. In this article we will prove the vanishing and non-vanishing properties of LiΛI(N,M)L_i\Lambda^I (N,M). We denote HIi(N,M)H^{i}_{I}(N,M) (resp. UiI(N,M)U^I_i(N,M)) by the generalized local cohomology modules (resp. the generalized local homology modules). As a technical tool we will construct several natural homomorphisms of LiΛI(N,M)L_i\Lambda^I (N,M), HIi(N,M)H^{i}_{I}(N,M) and UiI(N,M)U^I_i(N,M). We will investigate when these natural homomorphisms are isomorphisms. Moreover if MM is Artinian and NN is finitely generated then it is proven that LiΛI(N,M)L_i\Lambda^I (N,M) is isomorphic to UiI(N,M)U^I_i(N,M) for each iZi\in \mathbb{Z}. The similar result is obtained for HIi(N,M)H^i_{I}(N,M). Furthermore if both MM and NN are finitely generated with c=\grade(I,M)c=\grade(I,M). Then we are able to prove several necessary and sufficient conditions such that HIi(M)=0H^i_{I}(M)=0 for all ic.i\neq c. Here HIi(M)H^i_{I}(M) denote the ordinary local cohomology module.

Keywords

Cite

@article{arxiv.1502.01108,
  title  = {On generalized completion homology modules},
  author = {Waqas Mahmood},
  journal= {arXiv preprint arXiv:1502.01108},
  year   = {2017}
}

Comments

17 pages

R2 v1 2026-06-22T08:21:33.286Z