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The quasi-hereditary algebra associated to the radical bimodule over a hereditary algebra

Lutz Hille, Dieter Vossieck (2003)

Colloquium Mathematicae

Let Γ be a finite-dimensional hereditary basic algebra. We consider the radical rad Γ as a Γ-bimodule. It is known that there exists a quasi-hereditary algebra 𝓐 such that the category of matrices over rad Γ is equivalent to the category of Δ-filtered 𝓐-modules ℱ(𝓐,Δ). In this note we determine the quasi-hereditary algebra 𝓐 and prove certain properties of its module category.

The symplectic Gram-Schmidt theorem and fundamental geometries for 𝒜 -modules

Patrice P. Ntumba (2012)

Czechoslovak Mathematical Journal

Like the classical Gram-Schmidt theorem for symplectic vector spaces, the sheaf-theoretic version (in which the coefficient algebra sheaf 𝒜 is appropriately chosen) shows that symplectic 𝒜 -morphisms on free 𝒜 -modules of finite rank, defined on a topological space X , induce canonical bases (Theorem 1.1), called symplectic bases. Moreover (Theorem 2.1), if ( , φ ) is an 𝒜 -module (with respect to a -algebra sheaf 𝒜 without zero divisors) equipped with an orthosymmetric 𝒜 -morphism, we show, like in the classical...

Thick subcategories of the stable module category

D. Benson, Jon Carlson, Jeremy Rickard (1997)

Fundamenta Mathematicae

We study the thick subcategories of the stable category of finitely generated modules for the principal block of the group algebra of a finite group G over a field of characteristic p. In case G is a p-group we obtain a complete classification of the thick subcategories. The same classification works whenever the nucleus of the cohomology variety is zero. In case the nucleus is nonzero, we describe some examples which lead us to believe that there are always infinitely many thick subcategories concentrated...

Trisections of module categories

José A. de la Peña, Idun Reiten (2007)

Colloquium Mathematicae

Let A be a finite-dimensional algebra over a field k. We discuss the existence of trisections (mod₊ A,mod₀ A,mod₋ A) of the category of finitely generated modules mod A satisfying exactness, standardness, separation and adjustment conditions. Many important classes of algebras admit trisections. We describe a construction of algebras admitting a trisection of their module categories and, in special cases, we describe the structure of the components of the Auslander-Reiten quiver lying in mod₀ A.

When is the category of flat modules abelian?

J. García, J. Martínez Hernández (1995)

Fundamenta Mathematicae

Let Fl(R) denote the category of flat right modules over an associative ring R. We find necessary and sufficient conditions for Fl(R) to be a Grothendieck category, in terms of properties of the ring R.

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