On the structure of some Noetherian modules over group rings

In this paper, we study the structure of some Noetherian modules over group rings and deduce some statements regarding the structure of the groups involved. More precisely, we consider a module A over a group ring RG with the following property: A is a Noetherian RH-module for every subgroup H, which is not contained in the centralizer CG(A). If G is some generalized soluble group and R is a locally finite field or some Dedekind domain, we describe the structure of G/CG(A).

PSEUDO BUCHSBAUMNESS FOR IDEALIZATIONS OF NOETHERIAN MODULES OVER LOCAL RINGS

Let (R, 𝔪) be a Noetherian local ring with dim R = d and M an R-module with dim M < d. We prove in this paper that the idealization R ⋉ M of M over R is a pseudo Buchsbaum ring if and only if so is R.

BOUNDED AND FULLY BOUNDED MODULES

Generalizing the concept of right bounded rings, a module MR is called bounded if annR(M/N)≤eRR for all N≤eMR. The module MR is called fully bounded if (M/P) is bounded as a module over R/annR(M/P) for any ℒ2-prime submodule P◃MR. Boundedness and right boundedness are Morita invariant properties. Rings with all modules (fully) bounded are characterized, and it is proved that a ring R is right Artinian if and only if RR has Krull dimension, all R-modules are fully bounded and ideals of R are finitely generated as right ideals. For certain fully bounded ℒ2-Noetherian modules MR, it is shown that the Krull dimension of MR is at most equal to the classical Krull dimension of R when both dimensions exist.

GOLDIE DIMENSION, DUAL KRULL DIMENSION AND SUBDIRECT IRREDUCIBILITY

In this survey paper we present some results relating the Goldie dimension, dual Krull dimension and subdirect irreducibility in modules, torsion theories, Grothendieck categories and lattices. Our interest in studying this topic is rooted in a nice module theoretical result of Carl Faith [Commun. Algebra27 (1999), 1807–1810], characterizing Noetherian modules M by means of the finiteness of the Goldie dimension of all its quotient modules and the ACC on its subdirectly irreducible submodules. Thus, we extend his result in a dual Krull dimension setting and consider its dualization, not only in modules, but also in upper continuous modular lattices, with applications to torsion theories and Grothendieck categories.

Short modules and almost noetherian modules

It is proved that, for any ring $R$, a right $R$-module $M$ has the property that, for every submodule $N$, either $N$ or $M/N$ is Noetherian if and only if $M$ contains submodules $K \supseteq L$ such that $M/K$ and $L$ are Noetherian and $K/L$ is almost Noetherian.