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We show that the structure of blocks outside the critical hyperplanes of category O over any symmetrizable Kac-Moody algebra depends only on the corresponding integral Weyl group and its action on the parameters of the Verma modules by…

Representation Theory · Mathematics 2010-06-07 Peter Fiebig

A Coxeter group admits infinite-dimensional irreducible complex representations if and only if it is not finite or affine. In this paper, we provide a construction of some of those representations for certain Coxeter groups using some…

Representation Theory · Mathematics 2025-03-25 Hongsheng Hu

We continue the study of extended Weyl groups $W$, which are reflection groups. Further we recall the definition of a hyperbolic cover of an extended Weyl group, and show that the hyperbolic covers of the extended Weyl groups are extended…

Representation Theory · Mathematics 2025-08-12 Barbara Baumeister , Patrick Wegener , Sophiane Yahiatene

Ideas from Hodge theory have found important applications in representation theory. We give a survey of joint work with Ben Elias which uncovers Hodge theoretic structure in the Hecke category ("Soergel bimodules"). We also outline…

Representation Theory · Mathematics 2016-10-21 Geordie Williamson

We give a gentle introduction to the concept of folding. That is, we provide an elementary discussion of equivariant categories, their weighted Grothendieck groups, and the technical aspects of computing with them. We then perform the…

Representation Theory · Mathematics 2016-04-05 Ben Elias

We present equivalences between certain categories of vector bundles on projective varieties, namely cokernel bundles, Steiner bundles, syzygy bundles, and monads, and full subcategories of representations of certain quivers. As an…

Algebraic Geometry · Mathematics 2016-07-05 Marcos Jardim , Daniela M. Prata

We prove that the monoidal 2-category of cospans of finite linear orders and surjections is the universal monoidal category with an object X with a semigroup and a cosemigroup structures, where the two structures satisfy a certain…

Category Theory · Mathematics 2007-06-12 M. Menni , N. Sabadini , R. F. C. Walters

For an interval finite quiver $Q$, we introduce a class of flat representations. We classify the indecomposable projective objects in the category $\mathrm{rep}(Q)$ of pointwise finite dimensional representations. We show that an object in…

Representation Theory · Mathematics 2019-10-23 Pengjie Jiao

We generalize the monomorphism category from quiver (with monomial relations) to arbitrary finite dimensional algebras by a homological definition. Given two finite dimension algebras $A$ and $B$, we use the special monomorphism category…

Representation Theory · Mathematics 2018-04-25 Wei Hu , Xiu-Hua Luo , Bao-Lin Xiong , Guodong Zhou

Using the new approach to analytic geometry developed by Clausen and Scholze by means of condensed mathematics, we prove that for every affinoid analytic adic space $X$, pseudocoherent complexes, perfect complexes, and finite projective…

Algebraic Geometry · Mathematics 2021-11-16 Grigory Andreychev

We investigate invertible projective representations and their 2-categorical analogues using the language of TQFTs with defects. The main result is a freeness property for invertible projective representatios. While trivial in the…

Category Theory · Mathematics 2025-09-23 Domenico Fiorenza , Chetan Vuppulury

Given a finite dimensional algebra $A$, we consider certain sets of idempotents of $A$, called self-injective cores, to which we associate 2-subcategories of the 2-category of projective bimodules over $A$. We classify the simple transitive…

Representation Theory · Mathematics 2022-05-30 Mateusz Stroiński

We give a unifying description of all inequivalent vector bundles over the 2-dimensional sphere $S^2$ by constructing suitable global projectors $p$ via equivariant maps. Each projector determines the projective module of finite type of…

Mathematical Physics · Physics 2015-06-26 Giovanni Landi

In this paper, we study Coxeter systems with two-dimensional Davis-Vinberg complexes. We show that for a Coxeter group $W$, if $(W,S)$ and $(W,S')$ are Coxeter systems with two-dimensional Davis-Vinberg complexes, then there exists…

Group Theory · Mathematics 2007-05-23 Tetsuya Hosaka

The aim of this paper is to clarify the relation between the following objects: $ (a) $ rank 1 projective modules (ideals) over the first Weyl algebra $ A_1(\C)$; $ (b) $ simple modules over deformed preprojective algebras $…

Representation Theory · Mathematics 2007-06-21 Yuri Berest , Oleg Chalykh , Farkhod Eshmatov

A type of directed multigraph called a W-digraph is introduced to model the structure of certain representations of Hecke algebras, including those constructed by Lusztig and Vogan from involutions in a Weyl group. Building on results of…

Representation Theory · Mathematics 2021-07-01 Dean Alvis

We introduce the class of projective reflection groups which includes all complex reflection groups. We show that several aspects involving the combinatorics and the representation theory of all non exceptional irreducible complex…

Combinatorics · Mathematics 2009-02-05 Fabrizio Caselli

We describe the cone of deformations of a Coxeter permutahedron, or equivalently, the nef cone of the toric variety associated to a Coxeter complex. This family of polytopes contains polyhedral models for the Coxeter-theoretic analogs of…

Combinatorics · Mathematics 2020-03-03 Federico Ardila , Federico Castillo , Christopher Eur , Alexander Postnikov

We classify simple weight modules over infinite dimensional Weyl algebras and realize them using the action on certain localizations of the polynomial ring. We describe indecomposable projective and injective weight modules and deduce from…

Representation Theory · Mathematics 2012-10-22 Vyacheslav Futorny , Dimitar Grantcharov , Volodymyr Mazorchuk

We construct a functor from the Hecke category to a groupoid built from the underlying Coxeter group. This fixes a gap in an earlier work of the authors. This functor provides an abstract realization of the localization of the Hecke…

Representation Theory · Mathematics 2022-12-20 Ben Elias , Geordie Williamson