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Let $\Lambda$ be an artin algebra. We are going to consider full subcategories of $\mod\Lambda$ closed under finite direct sums and under submodules with infinitely many isomorphism classes of indecomposable modules. The main result asserts…

Representation Theory · Mathematics 2010-09-07 Claus Michael Ringel

The paper studies lower bounds for the dimensions of projective indecomposable modules for Chevalley groups G in defining characteristic p. The main result extending earlier one by Malle and Weigel (2008) determines the modules in question…

Group Theory · Mathematics 2012-02-08 Alexandre E. Zalesski

In this paper, we characterize Ulrich modules over cyclic quotient surface singularities by using the notion of special Cohen-Macaulay modules. We also investigate the number of indecomposable Ulrich modules for a given cyclic quotient…

Commutative Algebra · Mathematics 2017-04-07 Yusuke Nakajima , Ken-ichi Yoshida

In this paper we give a lower bound for the codimension of the Andreotti-Mayer loci in the moduli space of principally polarized complex abelian varieties. We also present a conjecture on this codimension.

Algebraic Geometry · Mathematics 2007-05-23 Ciro Ciliberto , Gerard van der Geer

The study of the combinatorics of the modular group and of Coxeter's friezes naturally leads to the investigation of a matrix equation, sometimes referred to as the Conway-Coxeter equation. The solutions of size $n$ of this equation, called…

Combinatorics · Mathematics 2026-04-15 Flavien Mabilat

We describe a straightforward construction of the pseudo-split absolutely pseudo-simple groups of minimal type with irreducible root systems of type $BC_n$; these exist only in characteristic $2$. We also give a formula for the dimensions…

Group Theory · Mathematics 2024-01-09 Michael Bate , Gerhard Röhrle , Damian Sercombe , David I. Stewart

We prove a number of results having to do with equipping type-I $\mathrm{C}^*$-algebras with compact quantum group structures, the two main ones being that such a compact quantum group is necessarily co-amenable, and that if the…

Operator Algebras · Mathematics 2020-08-11 Alexandru Chirvasitu , Jacek Krajczok , Piotr M. Sołtan

We classify irreducible finite-dimensional modules of a collection of real Lie superalgebras that includes the simple ones, their classical variants, complex Lie superalgebras after restriction of scalars, and all real Lie algebras. Our…

Representation Theory · Mathematics 2026-04-13 Siddhartha Sahi , Hadi Salmasian , Vera Serganova

We introduce the notion of integrable modules over $\imath$quantum groups (a.k.a. quantum symmetric pair coideal subalgebras). After determining a presentation of such modules, we prove that each integrable module over a quantum group is…

Quantum Algebra · Mathematics 2026-01-14 Hideya Watanabe

This paper studies the homological bounds of gentle algebras, i.e., the upper bounds for the sum of the projective and injective dimensions of indecomposable modules over gentle algebras. We provide conditions under which this sum is…

Representation Theory · Mathematics 2025-08-28 Yu-Zhe Liu , Xin Ma , Jiacheng Xu , Chao Zhang

It is proved that an irreducible quasifinite $W_\infty$-module is a highest or lowest weight module or a module of the intermediate series; a uniformly bounded indecomposable weight $W_\infty$-module is a module of the intermediate series.…

Representation Theory · Mathematics 2007-05-23 Yucai Su , Bin Xin

It is proved that Ulrich modules exist for a large class of local rings of dimension two. This complements earlier work of the authors and Ziquan Zhuang that described complete intersection domains of dimension two that admit no Ulrich…

Commutative Algebra · Mathematics 2025-10-06 Srikanth B. Iyengar , Linquan Ma , Mark E. Walker

We study finite dimensional algebras that appear as fibers of quantum orders over a given point of variety of center. We present the formula for the number of irreducible representations and check it for it for the algebra of twisted…

Quantum Algebra · Mathematics 2010-10-07 A. N. Panov

For the algebra L= K <x, d/dx, \int> of polynomial integro-differential operators over a field K of characteristic zero, a classification of indecomposable, generalized weight L-modules of finite length is given. Each such module is an…

Representation Theory · Mathematics 2017-01-02 Vladimir Bavula , Victor Bekkert , Vyacheslav Futorny

In this short note, we show that the Ginzburg-Vasserot map between the quantum affine algebra of type A_(n-1) and the equivariant K-theory group of the Steinberg Variety (of n-step flags in C^d) restricts and remains surjective at the level…

Quantum Algebra · Mathematics 2007-05-23 Schiffmann Olivier

We discuss the structure of finite groups for which the projective indecomposable modules have special given dimensions. In particular, we prove the converse of Fong's dimension formula for $p$-solvable groups. Furthermore, we characterize…

Group Theory · Mathematics 2012-02-27 Conchita Martínez-Pérez , Wolfgang Willems

Any finite set of linear operators on an algebra $A$ yields an operator algebra $B$ and a module structure on A, whose endomorphism ring is isomorphic to a subring $A^B$ of certain invariant elements of $A$. We show that if $A$ is a…

Rings and Algebras · Mathematics 2013-02-26 Inês Borges , Christian Lomp

An algebraic classification is given for spaces of holomorphic vector-valued modular forms of arbitrary real weight and multiplier system, associated to irreducible, T-unitarizable representations of the full modular group, of dimension…

Number Theory · Mathematics 2012-01-27 Christopher Marks

Given a finite dimensional algebra $\Lambda$, we show that a frequently satisfied finiteness condition for the category ${\cal P}^{\infty}(\Lambda\rm{-mod})$ of all finitely generated (left) $\Lambda$-modules of finite projective dimension,…

Representation Theory · Mathematics 2014-07-10 B. Huisgen-Zimmermann , S. O. Smalø

We consider simple modules over the McConnell--Pettit algebras. We show that both induction and contraction yield simple modules for the extremes of the global dimension.

Rings and Algebras · Mathematics 2011-06-23 Ashish Gupta