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We describe Calabi-Yau objects in the regular block of the (parabolic) BGG category $\mathcal{O}$ associated to a semi-simple finite dimensional complex Lie algebra. Each such object comes with a natural transformation from the Serre…

Representation Theory · Mathematics 2025-03-18 Volodymyr Mazorchuk

Let $\Lambda$ be a finite-dimensional algebra. A wide subcategory of $\mathsf{mod}\Lambda$ is called left finite if the smallest torsion class containing it is functorially finite. In this paper, we prove that the wide subcategories of…

Representation Theory · Mathematics 2024-08-23 Aslak Bakke Buan , Eric J. Hanson

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 a notion of generalized Auslander-Reiten duality on a Hom-finite Krull-Schmidt exact category $\mathcal{C}$. This duality induces the generalized Auslander-Reiten translation functors $\tau$ and $\tau^-$. They are mutually…

Representation Theory · Mathematics 2019-01-04 Pengjie Jiao

Let $G$ be a connected reductive algebraic group $G$ over an algebraically closed field $k$ of prime characteristic $p$, and $\ggg=\Lie(G)$. In this paper, we study modular representations of the reductive Lie algebra $\ggg$ with…

Representation Theory · Mathematics 2011-11-09 Yiyang Li , Bin Shu

We construct a new analogue of the BGG category $\mathcal O$ for the infinite-dimensional Lie algebras $\fg=\mathfrak{sl}(\infty),\mathfrak{o}(\infty), \mathfrak{sp}(\infty)$. A main difference with the categories studied in \cite{Nam} and…

Representation Theory · Mathematics 2019-03-05 Ivan Penkov , Vera Serganova

For a finite-dimensional algebra $\Lambda$ over an algebraically closed field $K$, it is known that the poset of $2$-term silting objects in $\mathrm{K}^b(\operatorname{proj}\Lambda)$ is isomorphic to the poset of functorially finite…

Representation Theory · Mathematics 2026-02-17 Esha Gupta

Let $G$ be a connected reductive algebraic group over an algebraically closed field of positive characteristic, $\mathfrak{g}$ be its Lie algebra, and $B$ be a Borel subgroup. We prove a formula for the dimensions of extension groups, in…

Representation Theory · Mathematics 2025-11-25 Simon Riche , Quan Situ

We classify the blocks, compute the Verma flags of tilting and projective modules in the BGG category $\mathcal O$ for the exceptional Lie superalgebra $G(3)$. The projective injective modules in $\mathcal O$ are classified. We also compute…

Representation Theory · Mathematics 2022-12-08 Shun-Jen Cheng , Weiqiang Wang

We construct a representation of the blob algebra over a ring allowing base change to every interesting (i.e. non--semisimple) specialisation which, in quasihereditary specialisations, passes to a full tilting module.

Representation Theory · Mathematics 2007-05-23 P P Martin , S Ryom-Hansen

In this paper, we study representations of the vertex operator algebra $L(k,0)$ at one-third admissible levels $k= -5/3, -4/3, -2/3$ for the affine algebra of type $G_2^{(1)}$. We first determine singular vectors and then obtain a…

Representation Theory · Mathematics 2010-11-16 Jonathan D. Axtell , Kyu-Hwan Lee

We study (support) $\tau$-tilting modules over the trivial extensions of finite dimensional algebras. More precisely, we construct two classes of (support)$\tau$-tilting modules in terms of the adjoint functors which extend and generalize…

Representation Theory · Mathematics 2022-02-21 Zhi-Wei Li , Xiaojin Zhang

We explain the construction of minimal tilting complexes for objects of highest weight categories and we study in detail the minimal tilting complexes for standard objects and simple objects. For certain categories of representations of…

Representation Theory · Mathematics 2022-11-21 Jonathan Gruber

In this paper we continue the project of generalizing tilting theory to the category of contravariant functors $Mod(C)$, from a skeletally small preadditive category $C$ to the category of abelian groups. We introduced the notion of a a…

Representation Theory · Mathematics 2015-10-02 R. Martinez-Villa , M. Ortiz-Morales

We give a diagrammatic presentation of the category of $\textbf{U}_q(\mathfrak{sl}_2)$-tilting modules $\mathfrak{T}$ for $q$ being a root of unity and introduce a grading on $\mathfrak{T}$. This grading is a "root of unity phenomenon" and…

Quantum Algebra · Mathematics 2017-03-27 Henning Haahr Andersen , Daniel Tubbenhauer

Let $L$ be a finite-dimensional Lie algebra over a field of non-zero characteristic and let $S$ be a subalgebra. Suppose that $X$ is a finite set of finite-dimensional $L$-modules. Let $D$ be the category of all finite-dimensional…

Rings and Algebras · Mathematics 2016-09-15 Donald W. Barnes

We generalize the Hernandez-Jimbo category O of representations of Borel subalgebras of quantum affine algebras to the case of quantum loop algebras for arbitrary Kac-Moody g (as well as related algebras, such as quantum toroidal gl_1).…

Representation Theory · Mathematics 2025-09-17 Andrei Neguţ

We show, in full generality, that Lusztig's $\mathbf{a}$-function describes the projective dimension of both indecomposable tilting modules and indecomposable injective modules in the regular block of the BGG category $\mathcal{O}$, proving…

Representation Theory · Mathematics 2010-04-02 Volodymyr Mazorchuk

Fix a finite-dimensional simple Lie algebra $\mathfrak{g}$ and let $\mathfrak{g}_J\subseteq\mathfrak{g}$ be a Lie subalgebra coming from a Dynkin diagram inclusion. Then, the corresponding restriction functor is not essentially surjective…

Representation Theory · Mathematics 2026-01-06 Théo Pinet

We show that the Whittaker functor on a regular block of the BGG-category $\mathcal{O}$ of a semisimple complex Lie algebra can be obtained by composing a translation to the wall functor with Soergel and Mili\v{c}i\'{c}'s equivalence…

Representation Theory · Mathematics 2023-07-07 Juan Camilo Arias , Erik Backelin