Algèbres graduées normales II - Construction d’un schéma sur certains anneaux -gradués
Algèbres simples centrales sur les corps de fonctions de deux variables
À toute classe dans le groupe de Brauer d’un corps sont associés deux entiers, l’indice (degré d’un corps gauche représentant la classe) et l’exposant (ordre de la classe dans le groupe de Brauer). L’exposant divise l’indice, mais ne lui est pas nécessairement égal. Lorsque est un corps de nombres, c’est un théorème des années 1930 qu’exposant et indice coïncident. A. J. de Jong (Duke Math. J. 123 (2004) 71-94) a montré récemment qu’ils coïncident aussi lorsque est un corps de fonctions de...
Algunas observaciones acerca de matrices triangulares sobre anillos
Almost Abelian rings
A ring is defined to be left almost Abelian if implies for and , where and stand respectively for the set of idempotents and the set of nilpotents of . Some characterizations and properties of such rings are included. It follows that if is a left almost Abelian ring, then is -regular if and only if is an ideal of and is regular. Moreover it is proved that (1) is an Abelian ring if and only if is a left almost Abelian left idempotent reflexive ring. (2) is strongly...
Almost approximately convex functions
Almost smooth algebras
Almost split sequences and module categories: A complementary view to Auslander-Reiten Theory
We take a complementary view to the Auslander-Reiten trend of thought: Instead of specializing a module category to the level where the existence of an almost split sequence is inferred, we explore the structural consequences that result if we assume the existence of a single almost split sequence under the most general conditions. We characterize the structure of the bimodule with an underlying ring solely assuming that there exists an almost split sequence of left -modules . and are...
Almost split sequences for non-regular modules
Let A be an Artin algebra and let be an almost split sequence of A-modules with the indecomposable. Suppose that X has a projective predecessor and Z has an injective successor in the Auslander-Reiten quiver of A. Then r ≤ 4, and r = 4 implies that one of the is projective-injective. Moreover, if is a source map with the indecomposable and X on an oriented cycle in , then t ≤ 4 and at most three of the are not projective. The dual statement for a sink map holds. Finally, if an arrow...
Almost Split Sequences over p-adic Rings.
Almost-flat modules
We present general properties for almost-flat modules and we prove that a self-small right module is almost flat as a left module over its endomorphism ring if and only if the class of -static modules is closed under the kernels.
Amalgamating commutative regular rings
Amalgams of Weyl algebras and the ... (V, ...) conjecture.
An action-free characterization of weak Hopf-Galois extensions.
An Algorithm for Lifting Points in a Tropical Variety
An algorithm for the decomposition of ideals of the group ring of a symmetric group.
An alternate criterion of colocalized-localized modules.
The aim of this note is to express a module which is localized as well as colocalized in terms of an object of an intersecting subcategory related to static modules.
An analogue of holonomic -modules on smooth varieties in positive characteristics.
An analogue of the Duistermaat-van der Kallen theorem for group algebras
Let G be a group, R an integral domain, and V G the R-subspace of the group algebra R[G] consisting of all the elements of R[G] whose coefficient of the identity element 1G of G is equal to zero. Motivated by the Mathieu conjecture [Mathieu O., Some conjectures about invariant theory and their applications, In: Algèbre non Commutative, Groupes Quantiques et Invariants, Reims, June 26–30, 1995, Sémin. Congr., 2, Société Mathématique de France, Paris, 1997, 263–279], the Duistermaat-van der Kallen...
An Application of a Theorem of Ziegler.
An application of Zassenhaus' unit theorem