The shift functor and the comprehensive factorization for internal groupoids
The paper studies the structure of functors in the category of functors from finite dimensional -vector spaces to -vector spaces, where is a finite functor and is the injective functor . A detection theorem is proved for sub-functors of such functors, which is the basis of the proof that the functors are artinian of type one.
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...
Let be any rational surface. We construct a tilting bundle on . Moreover, we can choose in such way that its endomorphism algebra is quasi-hereditary. In particular, the bounded derived category of coherent sheaves on is equivalent to the bounded derived category of finitely generated modules over a finite dimensional quasi-hereditary algebra . The construction starts with a full exceptional sequence of line bundles on and uses universal extensions. If is any smooth projective variety...
We show the Tychonoff's theorem for a Grothendieck category with a set of small projective generators. Strictly quasi-finite objects for semiartinian Grothendieck categories are characterized. We apply these results to the study of the Morita duality of dual algebra of a coalgebra.
We investigate the triangulated hull of orbit categories of the perfect derived category and the bounded derived category of a ring concerning the power of the suspension functor. It turns out that the triangulated hull corresponds to the full subcategory of compact objects of certain triangulated categories of periodic complexes. This specializes to Stai and Zhao’s result on the finite dimensional algebra of finite global dimension. As the first application, if , are flat algebras over a commutative...
M. Herschend, Y. Liu, H. Nakaoka introduced -exangulated categories, which are a simultaneous generalization of -exact categories and -angulated categories. This paper consists of two results on -exangulated categories: (1) we give an equivalent characterization of axiom (EA2); (2) we provide a new way to construct a closed subfunctor of an -exangulated category.
In this article, we develop a geometric method to construct solutions of the classical Yang–Baxter equation, attaching a family of classical -matrices to the Weierstrass family of plane cubic curves and a pair of coprime positive integers. It turns out that all elliptic -matrices arise in this way from smooth cubic curves. For the cuspidal cubic curve, we prove that the obtained solutions are rational and compute them explicitly. We also describe them in terms of Stolin’s classication and prove...