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We give an explicit combinatorial description of the category Perv(S,N) of perverse sheaves on an oriented surface S (with boundary) with singularities at a given finite set N. The description is given in terms of any spanning graph K in S…

Algebraic Topology · Mathematics 2016-01-11 Mikhail Kapranov , Vadim Schechtman

We present a detailed introduction of the theory of constructible sheaf complexes in the complex algebraic and analytic setting. All concepts are illustrated by many interesting examples and relevant applications, while some important…

Algebraic Geometry · Mathematics 2021-06-03 Laurenţiu G. Maxim , Jörg Schürmann

We provide a description of Iwahori-Whittaker equivariant perverse sheaves on affine flag varieties associated to tamely ramified reductive groups, in terms of Langlands dual data. This extends the work of Arkhipov-Bezrukavnikov from the…

Representation Theory · Mathematics 2024-11-06 Rızacan Çiloğlu

Motivated by the polynomial representation theory of the general linear group and the theory of symplectic singularities, we study a category of perverse sheaves with coefficients in a field $k$ on any affine unimodular hypertoric variety.…

Algebraic Geometry · Mathematics 2017-09-12 Tom Braden , Carl Mautner

We survey recent developments in the study of perverse sheaves on semi-abelian varieties. As concrete applications, we discuss various obstructions on the homotopy type of complex algebraic manifolds (expressed in terms of their cohomology…

Algebraic Topology · Mathematics 2019-02-15 Yongqiang Liu , Laurentiu Maxim , Botong Wang

We introduce the notion of filtered perversity of a filtered differential complex on a complex analytic manifold $X$, without any assumptions of coherence, with the purpose of studying the connection between the pure Hodge modules and the…

alg-geom · Mathematics 2008-02-03 P. Bressler , M. Saito , B. Youssin

We introduce and study the category of modular (i.e. with coefficient of positive characteristic) monodromic perverse sheaves on complex stratified $T$-varieties, with $T$ a complex algebraic torus. In particular, we show that under…

Representation Theory · Mathematics 2020-05-07 Valentin Gouttard

We give a complete quiver description of the category of perverse sheaves on Hermitian symmetric spaces in types A and D, constructible with respect to the Schubert stratification. The calculation is microlocal, and uses the action of the…

Algebraic Geometry · Mathematics 2007-05-23 Tom Braden

The purpose of this talk is to present an (apparently) new way to look at the intersection complex of a singular variety over a finite field, or, more generally, at the intermediate extension functor on pure perverse sheaves, and an…

Number Theory · Mathematics 2018-06-27 Sophie Morel

In this note, we provide a quick introduction to the study of the Milnor fibration via the derived category and perverse sheaves. This is primarily a dictionary for translating from the standard topological setting to the derived category…

Algebraic Geometry · Mathematics 2012-07-31 David B. Massey

We introduce, on a topological space X, a class of stacks of abelian categories we call "stacks of type P." This class of stacks includes the stack of perverse sheaves (of any perversity, constructible with respect to a fixed…

Representation Theory · Mathematics 2008-01-22 David Treumann

We introduce a notion of complexity of a complex of ell-adic sheaves on a quasi-projective variety and prove that the six operations are "continuous", in the sense that the complexity of the output sheaves is bounded solely in terms of the…

Algebraic Geometry · Mathematics 2022-04-28 W. Sawin , A. Forey , J. Fresán , E. Kowalski

We give an explicit combinatorial description of the deformation theory of the Abelian category of (quasi)coherent sheaves on any separated Noetherian scheme $X$ via the deformation theory of path algebras of quivers with relations, by…

Algebraic Geometry · Mathematics 2023-12-08 Severin Barmeier , Zhengfang Wang

We revisit generic vanishing results for perverse sheaves with any field coefficients on a complex semi-abelian variety, and indicate several topological applications. In particular, we obtain finiteness properties for the integral…

Algebraic Topology · Mathematics 2017-08-01 Yongqiang Liu , Laurentiu Maxim , Botong Wang

This paper studies abelian categories that can be decomposed into smaller abelian categories via iterated recollements - such a decomposition we call a stratification. Examples include the categories of (equivariant) perverse sheaves and…

Representation Theory · Mathematics 2025-06-23 Giulian Wiggins

For perverse sheaves K on abelian varieties X defined over a finitely generated field F we prove that the Euler-Poincare characteristic (defined for the extension of K to the algebraic closure of F) is non-negative.

Algebraic Geometry · Mathematics 2015-06-09 Rainer Weissauer

Let $k$ be a field of characteristic zero with a fixed embedding $\sigma:k\hookrightarrow \mathbb{C}$ into the field of complex numbers. Given a $k$-variety $X$, we use the triangulated category of \'etale motives with rational coefficients…

Algebraic Geometry · Mathematics 2023-10-26 Florian Ivorra , Sophie Morel

We prove a criterion for determining whether the normalization of a complex analytic space on which the constant sheaf is perverse is a rational homology manifold, using a perverse sheaf known as the multiple-point complex. This perverse…

Algebraic Geometry · Mathematics 2018-08-13 Brian Hepler

We consider a hyperplane arrangement in $\mathbb{C}^n$ defined over $\mathbb{R}$, and the associated natural stratification of $\mathbb{C}^n$. The category of perverse sheaves smooth with respect to this stratification was described by…

Representation Theory · Mathematics 2020-11-17 Asilata Bapat

The goal of this paper is to explain how basic properties of perverse sheaves sometimes translate via Riemann-Hilbert correspondences (in both characteristic $0$ and characteristic $p$) to highly non-trivial properties of singularities,…

Algebraic Geometry · Mathematics 2025-03-26 Bhargav Bhatt , Manuel Blickle , Gennady Lyubeznik , Anurag K. Singh , Wenliang Zhang