On the cofiniteness of generalized local cohomology modules

Abstract

Let $R$ be a commutative Noetherian ring, $I$ an ideal of $R$ and $M$, $N$ two finitely generated $R$-modules. The aim of this paper is to investigate the $I$-cofiniteness of generalized local cohomology modules $\displaystyle H^j_I(M,N)=\dlim\Ext^j_R(M/I^nM,N)$ of $M$ and $N$ with respect to $I$. We first prove that if $I$ is a principal ideal then $H_I^j(M,N)$ is $I$-cofinite for all $M,N$ and all $j$. Secondly, let $t$ be a non-negative integer such that $\dim\Supp(H^j_I(M,N))\le 1 \text{for all} j<t.$ Then $H_I^j(M,N)$ is $I$-cofinite for all $j<t$ and $\Hom(R/I,H^t_I(M,N))$ is finitely generated. Finally, we show that if $\dim (M)\le 2$ or $\dim (N)\le 2$ then $H_I^j(M,N)$ is $I$-cofinite for all $j$.

arXiv comment16 pages

Cited by in corpus (1)

• Gorenstein Homology and Finiteness Properties of Local (Co)homology