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Countably thick modules

Ali Abdel-Mohsen, Mohammad Saleh (2005)

Archivum Mathematicum

The purpose of this paper is to further the study of countably thick modules via weak injectivity. Among others, for some classes of modules in σ [ M ] we study when direct sums of modules from satisfies a property in σ [ M ] . In particular, we get characterization of locally countably thick modules, a generalization of locally q.f.d. modules.

Derived endo-discrete artin algebras

Raymundo Bautista (2006)

Colloquium Mathematicae

Let Λ be an artin algebra. We prove that for each sequence ( h i ) i of non-negative integers there are only a finite number of isomorphism classes of indecomposables X b ( Λ ) , the bounded derived category of Λ, with l e n g t h E ( X ) H i ( X ) = h i for all i ∈ ℤ and E(X) the endomorphism ring of X in b ( Λ ) if and only if b ( M o d Λ ) , the bounded derived category of the category M o d Λ of all left Λ-modules, has no generic objects in the sense of [4].

Differentiation and splitting for lattices over orders

Wolfgang Rump (2001)

Colloquium Mathematicae

We extend our module-theoretic approach to Zavadskiĭ’s differentiation techniques in representation theory. Let R be a complete discrete valuation domain with quotient field K, and Λ an R-order in a finite-dimensional K-algebra. For a hereditary monomorphism u: P ↪ I of Λ-lattices we have an equivalence of quotient categories ̃ u : Λ - l a t / [ ] δ u Λ - l a t / [ B ] which generalizes Zavadskiĭ’s algorithms for posets and tiled orders, and Simson’s reduction algorithm for vector space categories. In this article we replace u by a more...

Directing components for quasitilted algebras

Flávio Coelho (1999)

Colloquium Mathematicae

We show here that a directing component of the Auslander-Reiten quiver of a quasitilted algebra is either postprojective or preinjective or a connecting component.

Estimates of global dimension

Wei Jiaqun (2006)

Czechoslovak Mathematical Journal

In this note we show that for a * n -module, in particular, an almost n -tilting module, P over a ring R with A = E n d R P such that P A has finite flat dimension, the upper bound of the global dimension of A can be estimated by the global dimension of R and hence generalize the corresponding results in tilting theory and the ones in the theory of * -modules. As an application, we show that for a finitely generated projective module over a VN regular ring R , the global dimension of its endomorphism ring is not more...

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