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The purpose of this paper is to explain why the functor that sends a stratified topological space $S$ to the $\infty$-category of constructible (hyper)sheaves on $S$ with coefficients in a large class of presentable $\infty$categories is…

Algebraic Topology · Mathematics 2022-09-09 Peter J. Haine , Mauro Porta , Jean-Baptiste Teyssier

Working in the soft-element (classical) viewpoint, we introduce \emph{soft bitopological groups}: soft groups endowed with two soft topologies such that the induced topologies on the set of soft elements make the soft-element group into a…

General Topology · Mathematics 2026-02-16 S. Ray

Butz and Moerdijk famously showed that every (Grothendieck) topos with enough points is equivalent to the category of sheaves on some topological groupoid. We give an alternative, more algebraic construction in the special case of a topos…

Category Theory · Mathematics 2019-06-07 Jens Hemelaer

We study the cluster category of a canonical algebra A in terms of the hereditary category of coherent sheaves over the corresponding weighted projective line X. As an application we determine the automorphism group of the cluster category…

Representation Theory · Mathematics 2020-09-28 Michael Barot , Dirk Kussin , Helmut Lenzing

We introduce the notion of (co-)filtered sheaves on quotients of moment graphs by a group action. We then introduce a (co-)filtered version of the canonical sheaves of Braden and MacPherson and show that their global sections are the…

Representation Theory · Mathematics 2015-08-25 Peter Fiebig , Martina Lanini

We construct loops which are semidirect products of groups of affinities. As their elements in many cases one may take transversal subspaces of an affine space. In particular we obtain in this manner smooth loops having Lie groups of affine…

Group Theory · Mathematics 2015-07-01 Ágota Figula , Karl Strambach

Let $G$ be a connected reductive complex algebraic group, and $E$ a complex elliptic curve. Let $G_E$ denote the connected component of the trivial bundle in the stack of semistable $G$-bundles on $E$. We introduce a complex analytic…

Representation Theory · Mathematics 2021-01-01 Penghui Li , David Nadler

Let $\mathcal C$ be the category of finite graphs. Lov\`{a}sz shows that the semi-ring of isomorphism classes of $\mathcal C$ (with coproduct as sum, and product as multiplication) is embedded into the direct product of the semi-ring of…

Category Theory · Mathematics 2022-07-14 Shoma Fujino , Makoto Matsumoto

A group, defined as set with associative multiplication and inverse, is a natural structure describing the symmetry of a space. The concept of group generalizes to group objects internal to other categories than sets. But there are yet more…

Symplectic Geometry · Mathematics 2007-05-23 Christian Blohmann , Alan Weinstein

By homotopy linear algebra we mean the study of linear functors between slices of the $\infty$-category of $\infty$-groupoids, subject to certain finiteness conditions. After some standard definitions and results, we assemble said slices…

Category Theory · Mathematics 2018-04-20 Imma Gálvez-Carrillo , Joachim Kock , Andrew Tonks

The atoms of the Schanuel topos can be described as the pairs $(n,G)$ where $n$ is a finite set and $G$ is a subgroup of $\operatorname{Aut}(n)$. We give a general criterion on an atomic site ensuring that the atoms of the topos of sheaves…

Category Theory · Mathematics 2025-05-27 Jérémie Marquès

We introduce the notion of continuous twisted partial actions of a locally compact group on a C*-algebra. With such, we construct an associated C*-algebraic bundle called the semidirect product bundle. Our main theorem shows that, given any…

funct-an · Mathematics 2008-02-03 Ruy Exel

We introduce the concept of crossed product of a product system by a locally compact group. We prove that the crossed product of a row-finite and faithful product system by an amenable group is also a row-finite and faithful product system.…

Operator Algebras · Mathematics 2022-12-23 Valentin Deaconu , Leonard Huang

In this paper we observe that isomorphism classes of certain metrized vector bundles over P^1-{0,infinity} can be parameterized by arithmetic quotients of loop groups. We construct an asymptotic version of theta functions, which are defined…

Representation Theory · Mathematics 2015-05-12 Dongwen Liu

A "biased expansion" of a graph is a kind of branched covering graph with additional structure related to combinatorial homotopy of circles. Some but not all biased expansions are constructed from groups ("group expansions"); these include…

Combinatorics · Mathematics 2016-10-18 Thomas Zaslavsky

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

We are developing tools for working with arbitrary left-exact localizations of $\infty$-topoi. We introduce a notion of higher sheaf with respect to an arbitrary set of maps $\Sigma$ in an $\infty$-topos $\mathscr{E}$. We show that the full…

Category Theory · Mathematics 2022-03-02 Mathieu Anel , Georg Biedermann , Eric Finster , André Joyal

Let $X^\bullet$ be a cosimplicial object in a pointed $\infty$-category. We show that the fiber of $\mathrm{Tot}_m(X^\bullet) \to \mathrm{Tot}_n(X^\bullet)$ depends only on the pointed cosimplicial object $\Omega^k X^\bullet$ and is in…

Algebraic Topology · Mathematics 2015-12-21 Akhil Mathew , Vesna Stojanoska

We argue that for a certain class of symplectic manifolds the category of A-branes (which includes the Fukaya category as a full subcategory) is equivalent to a noncommutative deformation of the category of B-branes (which is equivalent to…

High Energy Physics - Theory · Physics 2007-05-23 Anton Kapustin

Metric (graph) bundles generalize the notion of fiber bundles to the context of geometric group theory and were introduced by Mj and Sardar. Suppose $X$ is a metric (graph) bundle over $B$ such that the fibers are (uniformly) hyperbolic,…

Geometric Topology · Mathematics 2025-07-10 Rakesh Halder