Automorphismen und Antiautomorphismen von Tensoralgebren.
Automorphismes de certains completés du corps de Weyl quantique.
Automorphisms and f-simplicity in skew polynomial rings
Automorphisms of completely primary finite rings of characteristic p
A completely primary ring is a ring R with identity 1 ≠ 0 whose subset of zero-divisors forms the unique maximal ideal . We determine the structure of the group of automorphisms Aut(R) of a completely primary finite ring R of characteristic p, such that if is the Jacobson radical of R, then ³ = (0), ² ≠ (0), the annihilator of coincides with ² and , the finite field of elements, for any prime p and any positive integer r.
Automorphisms of free nilpotent associative algebras.
Automorphisms of Representation Finite Algebras.
Azumaya algebras of a ring with a finite automorphism group.
Bounded Picard groups
Caractérisation des groupes de cohomologie d'un groupe topologique en termes de suites exactes
Cellular covers of cotorsion-free modules
In this paper we improve recent results dealing with cellular covers of R-modules. Cellular covers (sometimes called colocalizations) come up in the context of homotopical localization of topological spaces. They are related to idempotent cotriples, idempotent comonads or coreflectors in category theory. Recall that a homomorphism of R-modules π: G → H is called a cellular cover over H if π induces an isomorphism , where π⁎(φ) = πφ for each (where maps are acting on the left). On the one hand,...
Centralizer Theorems for Hopf Type Galois Extensions.
Centralizers on semiprime rings
The main result: Let be a -torsion free semiprime ring and let be an additive mapping. Suppose that holds for all . In this case is a centralizer.
Clifford theory for group-graded rings.
Clifford theory for group-graded rings. II.
Codimension B-W d’un idéal à droite non nul de
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...
Compatible ideals and radicals of Ore extensions.
Cyclic extensions and crossed-products
Degree estimate for subalgebras generated by two elements
We develop a new combinatorial method to deal with a degree estimate for subalgebras generated by two elements in different environments. We obtain a lower bound for the degree of the elements in two-generated subalgebras of a free associative algebra over a field of zero characteristic. We also reproduce a somewhat refined degree estimate of Shestakov and Umirbaev for the polynomial algebra, which plays an essential role in the recent celebrated solution of the Nagata conjecture and the strong...
Dimensions globales des extensions de Ore et des algèbres de Weyl
Dual dimension of modules over normalizing extensions.
Let S = Σi=1n Rai be a finite normalizing extension of R and suppose that SM is a left S-module. Denote by crk(A) the dual Goldie dimension of the module A. We show that crk(RM) ≤ n · crk(SM) if either SM is artinian or the group homomorphism M → aiM given by x → aix is an isomorphism.