On the weak regularity of semigroup rings.
On topologies over rings.
On torsionfree classes which are not precover classes
In the class of all exact torsion theories the torsionfree classes are cover (precover) classes if and only if the classes of torsionfree relatively injective modules or relatively exact modules are cover (precover) classes, and this happens exactly if and only if the torsion theory is of finite type. Using the transfinite induction in the second half of the paper a new construction of a torsionfree relatively injective cover of an arbitrary module with respect to Goldie’s torsion theory of finite...
On twisted group algebras of OTP representation type
Assume that S is a commutative complete discrete valuation domain of characteristic p, S* is the unit group of S and is a finite group, where is a p-group and B is a p’-group. Denote by the twisted group algebra of G over S with a 2-cocycle λ ∈ Z²(G,S*). We give necessary and sufficient conditions for to be of OTP representation type, in the sense that every indecomposable -module is isomorphic to the outer tensor product V W of an indecomposable -module V and an irreducible -module...
On unit-regular ideals.
On weak center Galois extensions of rings.
On weakened -skew Armendariz rings
In this note, for a ring endomorphism and an -derivation of a ring , the notion of weakened -skew Armendariz rings is introduced as a generalization of -rigid rings and weak Armendariz rings. It is proved that is a weakened -skew Armendariz ring if and only if is weakened -skew Armendariz if and only if is weakened -skew Armendariz ring for any positive integer .
On weakly reversible rings.
On -singular and -extending modules
Let be a module and be a class of modules in which is closed under isomorphisms and submodules. As a generalization of essential submodules Özcan in [8] defines a -essential submodule provided it has a non-zero intersection with any non-zero submodule in . We define and investigate -singular modules. We also introduce -extending and weakly -extending modules and mainly study weakly -extending modules. We give some characterizations of -co-H-rings by weakly -extending modules. Let ...
On -separability in skew polynomial rings.
One-dimensional infinitesimal-birational duality through differential operators
The structure of filtered algebras of Grothendieck's differential operators on a smooth fat point in a curve and graded Poisson algebras of their principal symbols is explicitly determined. A related infinitesimal-birational duality realized by a Springer type resolution of singularities and the Fourier transformation is presented. This algebro-geometrical duality is quantized in appropriate sense and its quantum origin is explained.
Opérateurs sur les polynômes non commutatifs définitions et notations
Opérations d'Adams sur certains groupes de Grothendieck
Ordering Epic R-Fields
Ordinary selfdistributive rings
Left selfdistributive rings (i.e., ) which are semidirect sums of boolean rings and rings nilpotent of index at most 3 are studied.
Ore extensions over near pseudo-valuation rings.
Orthogonal Gelfand-Zetlin algebras. I.
Outer automorphisms of endomorphism algebras
Commutative rings over which no endomorphism algebra has an outer automorphism are studied.
Over-rings of an (HNP)-ring