Constructing arbitrary torsion elements for a local cohomology module

In this paper we study relative and Tate cohomology of modules of finite Gorenstein injective dimension. Using these cohomology theories, we present variations of Grothendieck local cohomology modules, namely Gorenstein and Tate local cohomology modules. By applying a sort of Avramov-Martsinkovsky exact sequence, we show that these two variations of local cohomology are tightly connected to the generalized local cohomology modules introduced by J. Herzog. We discuss some properties of these modules and give some results concerning their vanishing and non-vanishing.

Let (R,𝔪) be a Noetherian local ring, M a finitely generated R-module with finite projective dimension n, N an arbitrary R-module, and 𝔞 be an ideal of R which is generated by s elements. In this article, we provide a surjective homomorphism from ordinary local cohomology module to top generalized local cohomology module , where P n, M is an nth syzygy of a projective resolution of M. Also, by using this epimorphism, we prove some results about the attached primes, coassociated primes, the Betti numbers, and Artinian properties of certain generalized local cohomology modules.

Given a local ring of positive prime characteristic there is a natural Frobenius action on its local cohomology modules with support at its maximal ideal. In this paper we study the local rings for which the local cohomology modules have only finitely many submodules invariant under the Frobenius action. In particular we prove that F-pure Gorenstein local rings as well as the face ring of a finite simplicial complex localized or completed at its homogeneous maximal ideal have this property. We also introduce the notion of an antinilpotent Frobenius action on an Artinian module over a local ring and use it to study those rings for which the lattice of submodules of the local cohomology that are invariant under Frobenius satisfies the ascending chain condition.

The Canonical Element Conjecture holds for those 3 3 -dimensional local rings of depth 2 whose second local cohomology module is a finite direct sum of cyclic modules, and for those 3 3 -dimensional local rings whose second local cohomology module is cyclic.

In this note, we first obtain some bounds for Noetherian dimension of Artinian local cohomology modules with respect to an ideal, in the cases of small levels. Secondly, in the case of top local cohomology modules, some bounds of Noetherian dimension for such modules are given. Received: April 24, 2023Revised: June 16, 2023Accepted: July 6, 2023

Let $$(R,\mathfrak {m})$$ be a commutative Noetherian local ring, M be a finitely generated R-module and $$\mathfrak {a}$$ , I and J are ideals of R. We investigate the structure of formal local cohomology modules of $$\mathfrak {F}^i_{\mathfrak {a},I,J}(M)$$ and $$\check{\mathfrak {F}}^i_{\mathfrak {a},I,J}(M)$$ with respect to a pair of ideals, for all $$i\ge 0$$ . The main subject of the paper is to study the finiteness properties and artinianness of $$\mathfrak {F}^i_{\mathfrak {a},I,J}(M)$$ and $$\check{\mathfrak {F}}^i_{\mathfrak {a},\mathfrak {m},J}(M)$$ . We study the maximum and minimum integer $$i\in \mathbb {N}$$ such that $$\mathfrak {F}^i_{\mathfrak {a},\mathfrak {m},J}(M)$$ and $$\check{\mathfrak {F}}^i_{\mathfrak {a},\mathfrak {m},J}(M)$$ are not Artinian and we obtain some results involving cosupport, coassociated and attached primes for formal local cohomology modules with respect to a pair of ideals. Also, we give an criterion involving the concepts of finiteness and vanishing of formal local cohomology modules and Cech-formal local cohomology modules with respect to a pair of ideals.

Local cohomology based on a nonclosed support defined by a pair of ideals

Algorithmic computation of local cohomology modules and the local cohomological dimension of algebraic varieties

Some properties of graded local cohomology modules

After motivating the question, we prove various results about the set of associated primes of Matlis duals of top local cohomology modules. In some cases, we can calculate this set. An easy application of this theory is the well-known fact that Krull dimension can be expressed by the vanishing of local cohomology modules.

The goal of this paper is twofold: on the one hand, motivated by questions raised by Schenzel, we explore situations where the Hartshorne–Lichtenbaum Vanishing theorem for local cohomology fails, leading us to simpler expressions of certain local cohomology modules. As application, we give new expressions of the endomorphism ring of these modules. On the other hand, building upon previous work by Àlvarez Montaner, we exhibit the shape of Lyubeznik tables of the so-called partially sequentially Cohen–Macaulay rings as introduced by Sbarra and Strazzanti.

We study a question raised by Eisenbud, Mustata, and Stillman regarding the injectivity of natural maps from Ext modules to local cohomology modules. We obtain some positive answers to this question which extend earlier results of Lyubeznik. In the process, we also prove a vanishing theorem for local cohomology modules which connects theorems previously known in the case of positive characteristic and in the case of monomial ideals.

Let A be a non-zero Artinian R-module. For an arbitrary ideal I of R, we show that the local homology module Hpx(A) is independent of the choice of x whenever 0 : AI = 0 : A(x1,...,xr). Thus, identifying these modules, we write HpI(A). In this paper we prove that there is a certain duality between HiI(A) and the local cohomology modules and provide some information about the vanishing local homology module HiI(A) which gives an improved form of the main results of [22].

Some uniform theorems on the artinianness of certain local cohomology modules are proven in a general situation. They generalize and imply previous results about the artinianness of some special local cohomology modules in the graded case.

Local cohomology modules via certain flat extension rings