A characterization of subgroup lattices of finite abelian groups.
A characterization of the Artinian modules.
A Class of Balanced Non-Uniserial Rings.
A criterion for quasi-heredity and the characteristic module.
A duality result for almost split sequences
Over an artinian hereditary ring R, we discuss how the existence of almost split sequences starting at the indecomposable non-injective preprojective right R-modules is related to the existence of almost split sequences ending at the indecomposable non-projective preinjective left R-modules. This answers a question raised by Simson in [27] in connection with pure semisimple rings.
A Krull-Schmidt theorem for Artinian modules over local rings.
A note on hereditary rings or non-singular rings with chain condition.
A representation theorem for Chain rings
A ring A is called a chain ring if it is a local, both sided artinian, principal ideal ring. Let R be a commutative chain ring. Let A be a faithful R-algebra which is a chain ring such that Ā = A/J(A) is a separable field extension of R̅ = R/J(R). It follows from a recent result by Alkhamees and Singh that A has a commutative R-subalgebra R₀ which is a chain ring such that A = R₀ + J(A) and R₀ ∩ J(A) = J(R₀) = J(R)R₀. The structure of A in terms of a skew polynomial ring over R₀ is determined.
Addendum to “Ring elements as sums of units”
We give a comment to Theorem 1.1 published in our paper “Ring elements as sums of units” [Cent. Eur. J. Math., 2009, 7(3), 395–399].
An Application of a Theorem of Ziegler.
Anneaux semi-artiniens
Artinische Ringe mit artinischem Radikal.
Characterizing rings by their modules
Closed extensions of R-modules in the case of a semi-artinian ring R
Si considerano le estensioni chiuse di un -modulo mediante un -modulo nel caso in cui sia un anello semi-artiniano, cioè un anello con la proprietà che per ogni quoziente sia soc . Tali estensioni sono caratterizzate dal fatto che deve essere un sottomodulo semi-puro di .
Complexity and periodicity
Let M be a finitely generated module over an Artin algebra. By considering the lengths of the modules in the minimal projective resolution of M, we obtain the Betti sequence of M. This sequence must be bounded if M is eventually periodic, but the converse fails to hold in general. We give conditions under which it holds, using techniques from Hochschild cohomology. We also provide a result which under certain conditions guarantees the existence of periodic modules. Finally, we study the case when...
Conditions which imply that subrings of artinian rings are artinian.
C(X) vs. C(X) modulo its socle
Let be the socle of C(X). It is shown that each prime ideal in is essential. For each h ∈ C(X), we prove that every prime ideal (resp. z-ideal) of C(X)/(h) is essential if and only if the set Z(h) of zeros of h contains no isolated points (resp. int Z(h) = ∅). It is proved that , where dim C(X) denotes the Goldie dimension of C(X), and the inequality may be strict. We also give an algebraic characterization of compact spaces with at most a countable number of nonisolated points. For each essential...
Decomposition properties in modules categories
Dually slender modules and steady rings.
Epis and monos which must be isos.