Clifford theory for group-graded rings.
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 .
We develop a technique for the study of K-coalgebras and their representation types by applying a quiver technique and topologically pseudocompact modules over pseudocompact K-algebras in the sense of Gabriel [17], [19]. A definition of tame comodule type and wild comodule type for K-coalgebras over an algebraically closed field K is introduced. Tame and wild coalgebras are studied by means of their finite-dimensional subcoalgebras. A weak version of the tame-wild dichotomy theorem of Drozd [13]...
Soit la première algèbre de Weyl sur . La codimension B-W d’un idéal à droite non nul de a été introduite par Yuri Berest et George Wilson. Nous montrons d’une part que cette codimension est invariante par la relation de Stafford : si , le corps de fractions de , et si , le groupe des -automorphismes de , sont tels que soit un idéal à droite de , alors . Nous relions d’autre part la codimension d’un idéal à la codimension de Gail Letzter-Makar Limanov, de , l’anneau des endomorphismes...
For a split graph order ℒ over a complete local regular domain of dimension 2 the indecomposable Cohen-Macaulay modules decompose - up to irreducible projectives - into a union of the indecomposable Cohen-Macaulay modules over graph orders of type •—• . There, the Cohen-Macaulay modules filtered by irreducible Cohen-Macaulay modules are in bijection to the homomorphisms under the bi-action of the groups , where for a prime π. This problem strongly depends on the nature of . If is regular,...
In this paper we investigate commutativity of ring with involution which admits a derivation satisfying certain algebraic identities on Jordan ideals of . Some related results for prime rings are also discussed. Finally, we provide examples to show that various restrictions imposed in the hypotheses of our theorems are not superfluous.