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This paper is a sequel to [Ga1]. We study the semi-infinite category on the Ran version of the affine Grassmannian, and study a particular object in it that we call the semi-infinite intersection cohomology sheaf. Unlike the situation of…

Algebraic Geometry · Mathematics 2021-11-04 Dennis Gaitsgory

Let G be a connected reductive group, P its parabolic subgroup. We consider the parabolic semi-infinite category of sheaves on the affine Grassmanian of G and construct the parabolic version of the semi-infinite IC-sheaf of each orbit. We…

Representation Theory · Mathematics 2025-07-08 G. Dhillon , S. Lysenko

We introduce the semi-infinite category of sheaves on the affine Grassmannian, and construct a particular object in it, which we call the the semi-infinite intersection cohomology sheaf. We relate it to several other entities naturally…

Algebraic Geometry · Mathematics 2021-11-02 Dennis Gaitsgory

This paper is a sequel to arXiv:2310.0638. Let G be a split reductive group. We define the parabolic semi-infinite category on the Ran version of the affine Grassmanian Gr_{G,Ran}. We study the semi-infinite parabolic IC-sheaf in this…

Representation Theory · Mathematics 2025-08-05 Gurbir Dhillon , Sergey Lysenko

For a simple algebraic group $G$ we study the space $Q$ of Quasimaps from the projective line $C$ to the flag variety of $G$. We prove that the global Intersection Cohomology of $Q$ carries a natural pure Tate Hodge structure, and compute…

alg-geom · Mathematics 2008-09-30 Boris Feigin , Michael Finkelberg , Alexander Kuznetsov , Ivan Mirković

This paper develops the algebraic foundation required to build a Zariski-type geometry for \emph{commutative ternary $\Gamma$-semirings}, where multiplication is an inherently triadic, multi-parametric interaction…

Rings and Algebras · Mathematics 2025-12-25 Chandrasekhar Gokavarapu , D. Madhusudhana Rao

We develop a new method for analyzing moduli problems related to the stack of pure coherent sheaves on a polarized family of projective schemes. It is an infinite-dimensional analogue of geometric invariant theory. We apply this to two…

Algebraic Geometry · Mathematics 2024-02-05 Daniel Halpern-Leistner , Andres Fernandez Herrero , Trevor Jones

Modules over a vertex operator algebra V give rise to sheaves of coinvariants on moduli of stable pointed curves. If V satisfies finiteness and semi-simplicity conditions, these sheaves are vector bundles. This relies on factorization, an…

Algebraic Geometry · Mathematics 2022-08-12 Chiara Damiolini , Angela Gibney , Daniel Krashen

We describe a general setting for the definition of semi-infinite cohomology of finite dimensional algebras, and provide its categorical interpretation. We apply this interpretation to compute semi-infinite cohomology of some modules over…

Quantum Algebra · Mathematics 2019-02-20 Roman Bezrukavnikov , Leonid Positselski

This article is a sequel to hep-th/9411050, q-alg/9412017, q-alg/9503013. Given a collection of $m$ finite factorizable sheaves $\{\CX_k\}$, we construct here some perverse sheaves over configuration spaces of points on a projective line…

q-alg · Mathematics 2008-02-03 M. Finkelberg , V. Schechtman

We introduce twisted matrix factorizations for quantum complete intersections of codimension two. For such an algebra, we show that in a given dimension, almost all the indecomposable modules with bounded minimal projective resolutions…

K-Theory and Homology · Mathematics 2017-10-23 Petter Andreas Bergh , Karin Erdmann

The Semiinfinite Flag Space appeared in the works of B.Feigin and E.Frenkel, and under different disguises was found by V.Drinfeld and G.Lusztig in the early 80-s. Another recent discovery (Beilinson-Drinfeld Grassmannian) turned out to…

alg-geom · Mathematics 2008-02-03 Michael Finkelberg , Ivan Mirković

A braided tensor category $FM_{\kappa}$ of `factorizable D-modules' over configuration spaces is introduced, analogous to the category $FS_q$ of factorizable sheaves from q-alg/9604001. This category is equivalent to the category of finite…

q-alg · Mathematics 2008-02-03 Sergei Khoroshkin , Vadim Schechtman

In this paper we construct some quantum analogues of the global Cousin complex for the flag variety in positive characteristic. Just like in the positive characteristic case, we obtain some remarkable resolutions of the contragradient…

Quantum Algebra · Mathematics 2007-05-23 Sergey Arkhipov

We study a category of semiinfinite sheaves on the affine flag variety of a connected reductive algebraic group, with coefficients in a field of arbitrary characteristic, generalizing some results of Gaitsgory and showing that this category…

Representation Theory · Mathematics 2025-03-25 Pramod N. Achar , Gurbir Dhillon , Simon Riche

The purpose of this paper is to describe an analogue of a construction of Costello in the context of finite-dimensional differential graded Frobenius algebras which produces closed forms on the decorated moduli space of Riemann surfaces. We…

Quantum Algebra · Mathematics 2015-05-18 Alastair Hamilton

Many interesting geometric structures can be described as regular infinitesimal flag structures, which occur as the underlying structures of parabolic geometries. Among these structures we have for instance conformal structures, contact…

Differential Geometry · Mathematics 2013-01-24 Katharina Neusser

We introduce a natural structure of a semigroup (isomorphic to a factorization semigroup of the unity in the symmetric group) on the set of irreducible components of Hurwitz space of marked degree $d$ coverings of $\mathbb P^1$ of fixed…

Algebraic Geometry · Mathematics 2015-05-18 Vik. S. Kulikov

Consider a Kleinian singularity $ \mathbb{C}^2/\Gamma $, where $ \Gamma $ is a finite subgroup of $ SL_2(\mathbb{C}) $. In this paper, we construct moduli spaces of framed sheaves on a projective Deligne-Mumford stack compactifying the…

Algebraic Geometry · Mathematics 2024-03-13 Søren Gammelgaard

Inspired by Morse theory, we introduce a topological stack Broken, which we refer to as the moduli stack of broken lines. We show that Broken can be presented as a Lie groupoid with corners and provide a combinatorial description of sheaves…

Algebraic Topology · Mathematics 2018-05-25 Jacob Lurie , Hiro Lee Tanaka
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