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Given a category fibered in groupoids over schemes with a log structure, one produces a category fibered in groupoids over log schemes. We classify the groupoid fibrations over log schemes that arise in this manner in terms of a categorical…

Algebraic Geometry · Mathematics 2011-03-14 W. D. Gillam

We give a simple description of the category of sheaves on the small etale site of an irreducible scheme whose local rings are geometrically unibranch and henselian, which affords a characterization of representable sheaves.

Algebraic Geometry · Mathematics 2024-12-11 Christophe Cornut

This is an announcement of a long paper in progress. On a locally compact space, we introduce the stack of ind-sheaves (ind-objects of the category of sheaves with compact support) and construct the analogous of the usual six operations on…

Algebraic Geometry · Mathematics 2007-05-23 Masaki Kashiwara , Pierre Schapira

In this paper, we investigate a sheaf-theoretic interpretation of stratification learning from geometric and topological perspectives. Our main result is the construction of stratification learning algorithms framed in terms of a sheaf on a…

Computational Geometry · Computer Science 2020-06-12 Adam Brown , Bei Wang

In the present paper, we show how to construct an algebraic sheaf by means of the topological generalized group defined by Molaei in [16] by considering both homotopy and sheaf theory.

Algebraic Topology · Mathematics 2018-06-12 Hatice Aslan , Hakan Efe

This is the first of a series of papers on sheaf theory on smooth and topological stacks and its applications. The main result of the present paper is the characterization of the twisted (by a closed integral three-form) de Rham complex on…

K-Theory and Homology · Mathematics 2014-10-01 Ulrich Bunke , Thomas Schick , Markus Spitzweck

Sheaves are objects of a local nature: a global section is determined by how it looks locally. Hence, a sheaf cannot describe mathematical structures which contain global or nonlocal geometric information. To fill this gap, we introduce the…

Category Theory · Mathematics 2016-10-26 Cecilia Flori , Tobias Fritz

We define the notion of sheaf in the context of doctrines. We prove the associate sheaf functor theorem. We show that grothendieck toposes and toposes obtained by the tripos to topos construction are instances of categories of sheaves for a…

Logic · Mathematics 2014-09-05 Fabio Pasquali

In a previous paper we outlined how discrete torsion can be understood geometrically as an analogue of orbifold U(1) Wilson lines. In this paper we shall prove the remaining details. More precisely, in this paper we describe gerbes in terms…

High Energy Physics - Theory · Physics 2007-05-23 Eric R. Sharpe

If $S$ is a scheme of finite type over $k=\cc $, let $\Xx /S$ denote the big etale site of schemes over $S$. We introduce {\em presentable group sheaves}, a full subcategory of the category of sheaves of groups on $\Xx /S$ which is closed…

alg-geom · Mathematics 2008-02-03 Carlos Simpson

The main goal of this paper is to establish close relations among sheaves of modules on atomic sites, representations of categories, and discrete representations of topological groups. We characterize sheaves of modules on atomic sites as…

Representation Theory · Mathematics 2025-05-07 Zhenxing Di , Liping Li , Li Liang , Fei Xu

We give a homotopy theoretic characterization of sheaves on a stack and, more generally, a presheaf of groupoids on an arbitary small site C. We use this to prove homotopy invariance and generalized descent statements for categories of…

Algebraic Topology · Mathematics 2007-08-21 Sharon Hollander

In this paper, we investigate the order algebraic structure in the category of sheaves on a given locale $X$. Since every localic topos has a generating set formed by its subterminal objects, we define a "point" of a partially ordered sheaf…

Category Theory · Mathematics 2015-07-10 Wei He

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 prove that an algebraic stack with affine stabilizers over an arbitrary base is \'etale-locally a quotient stack around any point with a linearly reductive stabilizer. This generalizes earlier work by the authors of this article (stacks…

Algebraic Geometry · Mathematics 2025-04-07 Jarod Alper , Jack Hall , David Rydh

We develop a "Soergel theory" for Bruhat-constructible perverse sheaves on the flag variety $G/B$ of a complex reductive group $G$, with coefficients in an arbitrary field $\Bbbk$. Namely, we describe the endomorphisms of the projective…

Representation Theory · Mathematics 2020-02-19 Roman Bezrukavnikov , Simon Riche

An \'{e}tale space over a topological space $Y$ is defined as a local homeomorphism from a topological space $X$ into $Y$. They often come up in topos theory because of the equivalence between sheaves and \'{e}tale spaces over a space. In…

Logic · Mathematics 2026-05-01 Matthew de Brecht

We construct a quasi-coherent sheaf of associative algebras which controls a category of $AV$-modules over a smooth quasi-projective variety. We establish a local structure theorem, proving that in \'etale charts these associative algebras…

Representation Theory · Mathematics 2026-02-02 Yuly Billig , Colin Ingalls

I categorify the definition of fibre bundle, replacing smooth manifolds with differentiable categories, Lie groups with coherent Lie 2-groups, and bundles with a suitable notion of 2-bundle. To link this with previous work, I show that…

Category Theory · Mathematics 2007-05-23 Toby Bartels

We initiate the study of sheaves on Cech closure spaces, providing a new, unified approach to sheaf theory on many of the major classes of spaces of interest to applications: topological spaces, finite simplicial complexes (seen as $T_0$…

Algebraic Topology · Mathematics 2025-10-21 Antonio Rieser