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We show that the equivariant small quantum $K$-group of a partial flag manifold is a quotient of that of the full flag manifold in a way that respects the Schubert classes. This is a $K$-theoretic analogue of the parabolic version of…

Algebraic Geometry · Mathematics 2026-04-24 Syu Kato

We study a natural enlargement of the BGG Category O for a semisimple Lie algebra: the category of weight modules with trivial central character and finite-dimensional weight spaces supported on the root lattice. We give a geometric…

Representation Theory · Mathematics 2025-12-05 Pablo Boixeda Alvarez , Calder Morton-Ferguson

We prove that the sheaf Euler characteristic of the product of a Schubert class and an opposite Schubert class in the quantum $K$-theory ring of a (generalized) flag variety $G/P$ is equal to $q^d$, where $d$ is the smallest degree of a…

Algebraic Geometry · Mathematics 2019-03-07 Anders S. Buch , Sjuvon Chung , Changzheng Li , Leonardo C. Mihalcea

Forgetting a subspace from a partial flag yields another partial flag composed of fewer subspaces. This induces a forgetful map $\pi : X \to X'$ between the corresponding flag varieties. We prove here that, for a degree large enough, the…

Algebraic Geometry · Mathematics 2022-02-03 Sybille Rosset

If G is a reductive group which acts on a linearized smooth scheme $X$ then we show that under suitable standard conditions the derived category of coherent sheaves of the corresponding GIT quotient stack $X^{ss}/G$ has a semi-orthogonal…

Algebraic Geometry · Mathematics 2018-01-19 Špela Špenko , Michel Van den Bergh

We find a new geometric incarnation for the principal block in the category of modules over a quantum group at a root of unity, realizing it as a full subcategory of microsheaves on a certain affine Springer fiber. We also prove a related…

Algebraic Geometry · Mathematics 2026-04-15 Roman Bezrukavnikov , Pablo Boixeda Alvarez , Michael McBreen , Zhiwei Yun

We show that the representation category of the quantum group of a non-degenerate bilinear form is monoidally equivalent to the representation category of the quantum group SL_q(2), for a well chosen non-zero parameter q. The main…

Quantum Algebra · Mathematics 2007-05-23 Julien Bichon

We give a block decomposition of the dg category of character sheaves on a simple and simply-connected complex reductive group $G$, similar to the one in generalized Springer correspondence. As a corollary, we identify the category of…

Representation Theory · Mathematics 2018-10-17 Penghui Li

In this paper we prove equivalences of categories relating the derived category of a block of the category of representations of a connected reductive algebraic group over an algebraically closed field of characteristic $p$ bigger than the…

Representation Theory · Mathematics 2018-04-13 Pramod N. Achar , Simon Riche

We give a pedagogical survey of those aspects of the abstract representation theory of quantum groups which are related to the Tannaka-Krein reconstruction problem. We show that every concrete semisimple tensor *-category with conjugates is…

Quantum Algebra · Mathematics 2007-05-23 M. Mueger , J. E. Roberts , L. Tuset

The category O of BGG can be thought of as a category of sheaves over the flag variety F in the sense that the algebra E of self-extensions of the trivial object of O is isomorphic to the cohomology algebra of the flag variety. A…

Quantum Algebra · Mathematics 2009-07-22 Pierre-Yves Gaillard

In the paper \cite{BK} we defined categories of equivariant quantum $\mathcal{O}_q$-modules and $\mathcal{D}_q$-modules on the quantum flag variety of $G$. We proved that the Beilinson-Bernstein localization theorem holds at a generic $q$.…

Representation Theory · Mathematics 2007-11-13 Erik Backelin , Kobi Kremnizer

We introduce the notion of a quasicoherent sheaf on a complex noncommutative two-torus $T$ as an ind-object in the category of holomorphic vector bundles on $T$. Extending the results of math.QA/0211262 and math.QA/0308136 we prove that the…

Quantum Algebra · Mathematics 2007-05-23 Alexander Polishchuk

We classify semisimple left module categories over the representation category of a type A quantum group whose fusion rules arise from the maximal torus. The classification is connected to equivariant Poisson structures on compact full flag…

Quantum Algebra · Mathematics 2025-10-15 Mao Hoshino

The paper is concerned with cohomology of the small quantum group at a root of unity, and of its upper triangular subalgebra, with coefficients in a tilting module. We relate it to a certain t-structure on the derived category of…

Representation Theory · Mathematics 2007-05-23 Roman Bezrukavnikov

Let G be a reductive algebraic group with a Borel subgroup B. We define the quasi-coherent Hecke category for the pair (G,B). For any regular Noetherian G-scheme X we construct a monoidal action of the Hecke category on the derived category…

Representation Theory · Mathematics 2015-10-27 Sergey Arkhipov , Tina Kanstrup

Let $G$ be an algebraic group and let $X$ be a smooth $G$-variety with two orbits: an open orbit and a a closed orbit of codimension $1$. We give an algebraic description of the category of $G$-equivariant vector bundles on $X$ under a mild…

Algebraic Geometry · Mathematics 2022-02-22 Lucas Mason-Brown , James Tao

In \cite{DFW} and \cite{Fu07}, little $q$-Schur algebras were introduced as homomorphic images of the infinitesimal quantum groups. In this paper, we will investigate representations of these algebras. We will classify simple modules for…

Representation Theory · Mathematics 2011-06-24 Jie Du , Qiang Fu , Jian-pan Wang

We give a formula for the smallest powers of the quantum parameters q that occur in a product of Schubert classes in the (small) quantum cohomology of general flag varieties G/P. We also include a complete proof of Peterson's quantum…

Algebraic Geometry · Mathematics 2016-09-07 W. Fulton , C. Woodward

In this thesis we study two main topics which culminate in a proof that four distinct definitions of the equivariant derived category of a smooth algebraic group $G$ acting on a variety $X$ are in fact equivalent. In the first part of this…

Algebraic Geometry · Mathematics 2023-02-01 Geoff Vooys