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We verify a finiteness conjecture of Feit on sources of simple modules over group algebras for various classes of finite groups related to the symmetric groups.

Representation Theory · Mathematics 2011-12-21 Susanne Danz , Jürgen Müller

Comparing the bounded derived categories of an algebra and of the endomorphism algebra of a given support {\tau}-tilting module, we find a relation between the derived dimensions of an algebra and of the endomorphism algebra of a given…

Representation Theory · Mathematics 2020-12-08 Yingying Zhang

This is a paper in a series that studies smooth relative Lie algebra homologies and cohomologies based on the theory of formal manifolds and formal Lie groups. In three previous papers, we introduce the notion of formal manifolds and study…

Differential Geometry · Mathematics 2025-01-22 Fulin Chen , Binyong Sun , Chuyun Wang

In this paper we prove that the cohomology groups with compact support of stacks of shtukas are modules of finite type over a Hecke algebra. As an application, we extend the construction of excursion operators, defined by V. Lafforgue on…

Algebraic Geometry · Mathematics 2024-04-17 Cong Xue

For a noetherian scheme, we introduce its unbounded stable derived category. This leads to a recollement which reflects the passage from the bounded derived category of coherent sheaves to the quotient modulo the subcategory of perfect…

Algebraic Geometry · Mathematics 2007-05-23 Henning Krause

Consider a finite-dimensional algebra $A$ and any of its moduli spaces $\mathcal{M}(A,\mathbf{d})^{ss}_{\theta}$ of representations. We prove a decomposition theorem which relates any irreducible component of…

Representation Theory · Mathematics 2018-09-25 Calin Chindris , Ryan Kinser

We state results from noncommutative deformation theory of modules over an associative $k$-algebra $A,$ $k$ a field, necessary for this work. We define a set of $A$-modules $\operatorname{aSpec}A$ containing the simple modules, whose…

Algebraic Geometry · Mathematics 2024-10-23 Arvid Siqveland

We classify the stable formulas in the theory of Dense Linear Orders without endpoints, the stable formulas in the theory of Divisible Abelian Groups, and the stable formulas without parameters in the theory of Real Closed Fields. The third…

Logic · Mathematics 2024-10-24 Daniel Max Hoffmann , Chieu-Minh Tran , Jinhe Ye

We study modular theory in hyperfinite von Neumann algebras, i.e. in those of type II or type III, from the viewpoint of a subregion charge sector decomposition. We address this symmetry resolution by considering infinite tensor products of…

High Energy Physics - Theory · Physics 2025-10-06 Giuseppe Di Giulio , Moritz Dorband , Johanna Erdmenger , Henri Scheppach

The dissertation focuses on decomposing a group algebra $kG$ over a field of positive characteristic into a direct sum of projective indecomposable modules. Such a decomposition is obtained together with the Artin--Wedderburn Theorem. The…

Rings and Algebras · Mathematics 2025-12-10 Eun H. Park

We construct from a finitary exact category with duality a module over its Hall algebra, called the Hall module, encoding the first order self-dual extension structure of the category. We study in detail Hall modules arising from the…

Representation Theory · Mathematics 2014-07-14 Matthew B. Young

We exhibit a bridge between the theory of cellular categories, used in algebraic topology and homological algebra, and the model-theoretic notion of stable independence. Roughly speaking, we show that the combinatorial cellular categories…

Category Theory · Mathematics 2022-04-05 Michael Lieberman , Jiří Rosický , Sebastien Vasey

We provide the main results of a deformation theory of smooth formal schemes. First we deal with the case of global lifting of smooth morphisms. We prove that the obstruction to the existence of a global lifting lies in a Ext^1 group. Then…

Algebraic Geometry · Mathematics 2008-01-21 Marta Perez

We introduce the notion of difference equation defined on a structured set. The symmetry group of the structure determines the set of difference operators. All main notions in the theory of difference equations are introduced as invariants…

q-alg · Mathematics 2019-08-17 Per K. Jakobsen , Valentin V. Lychagin

Always dealing with an arbitrary field we consider the variety $(k^{n\times n})^{p}$ under the action of $GL_{n}$ by simultaneous similarity. We define discrete and continuous invariants which completely determine the orbits. The discrete…

Representation Theory · Mathematics 2026-05-22 Klaus Bongartz , Shmuel Friedland

Automorphisms of finite order and real forms of "smooth" affine Kac-Moody algebras are studied, i.e. of 2-dimensional extensions of the algebra of smooth loops in a simple Lie algebra. It is shown that they can be parametrized by certain…

Rings and Algebras · Mathematics 2009-04-01 Ernst Heintze , Christian Groß

Representation stability is a theory describing a way in which a sequence of representations of different groups is related, and essentially contains a finite amount of information. Starting with Church-Ellenberg-Farb's theory of…

Representation Theory · Mathematics 2017-04-11 Nir Gadish

Following ideas of Lawvere and Linton we prove that classical varieties are precisely the exact categories with a varietal generator. This means a strong generator which is abstractly finite and regularly projective. An analogous…

Category Theory · Mathematics 2024-02-23 Jiri Adamek

The class of support $\tau$-tilting modules was introduced to provide a completion of the class of tilting modules from the point of view of mutations. In this article we study $\tau$-tilting finite algebras, i.e. finite dimensional…

Representation Theory · Mathematics 2019-02-13 Laurent Demonet , Osamu Iyama , Gustavo Jasso

In this paper, we give a geometric construction of string algebras and of their module categories. Our approach uses dissections of punctured Riemann surfaces with extra data at marked points, called labels. As an application, we give a…

Representation Theory · Mathematics 2024-03-13 Karin Baur , Raquel Coelho Simoes