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We rewrite classical topological definitions using the category-theoretic notation of arrows and are led to concise reformulations in terms of simplicial categories and orthogonality of morphisms, which we hope might be of use in the…

Category Theory · Mathematics 2018-07-19 Misha Gavrilovich , Konstantin Pimenov

This paper introduces the notion of complete connectedness of a Grothendieck topos, defined as the existence of a left adjoint to a left adjoint to a left adjoint to the global sections functor, and provides many examples. Typical examples…

Category Theory · Mathematics 2025-12-02 Ryuya Hora

Let $X$ be a scheme. In this text, we extend the known definitions of a topology on the set $X(R)$ of $R$-rational points from topological fields, local rings and ad\`ele rings to any ring $R$ with a topology. This definition is functorial…

Algebraic Geometry · Mathematics 2015-09-03 Oliver Lorscheid , Cecília Salgado

We consider cohomology of small categories with coefficients in a natural system in the sense of Baues and Wirsching. For any funtor L: K -> CAT, we construct a spectral sequence abutting to the cohomology of the Grothendieck construction…

Category Theory · Mathematics 2010-11-01 Teimuraz Pirashvili , Maria Julia Redondo

We prove that every Grothendieck topology induces a hereditary torsion pair in the category of presheaves of modules on a ringed site, and obtain a homological characterization of sheaves of modules: a presheaf of modules is a sheaf of…

Representation Theory · Mathematics 2025-07-30 Zhenxing Di , Liping Li , Li Liang

Simplicial presheaves on cartesian spaces provide a general notion of smooth spaces. There is a corresponding smooth version of the singular complex functor, which maps smooth spaces to simplicial sets. We consider the localisation of the…

Algebraic Topology · Mathematics 2022-11-16 Severin Bunk

In this paper, we present a generalization of Grothendieck pretopologies -- suited for semicartesian categories with equalizers $C$ -- leading to a closed monoidal category of sheaves, instead of closed cartesian category. This is proved…

Category Theory · Mathematics 2024-04-19 Ana Luiza Tenório , Hugo Luiz Mariano

Given a stratified topological space, we answer the question whether the functor from the derived category of constructible sheaves to the derived category of sheaves with constructible cohomology is an equivalence. We also establish basic…

Algebraic Geometry · Mathematics 2026-01-12 Valery Lunts , Olaf Schnuerer

Through the subsequent discussion we consider a certain particular sort of (topological) algebras, which may substitute the `` structure sheaf algebras'' in many--in point of fact, in all--the situations of a geometrical character that…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Anastasios Mallios

We systematically develop the theory of definable functors between compactly generated triangulated categories. Such functors preserve pure triangles, pure injective objects, and definable subcategories, and as such appear in a wide range…

Category Theory · Mathematics 2025-03-03 Isaac Bird , Jordan Williamson

Locally ordered spaces can be used as topological models of concurrent programs: the local order models the irreversibility of time during execution. Under certain conditions, one can even work with locally ordered manifolds. In this paper,…

Algebraic Topology · Mathematics 2026-05-01 Yorgo Chamoun , Emmanuel Haucourt

We present and characterize the classes of Grothendieck toposes having enough supercompact objects or enough compact objects. In the process, we examine the subcategories of supercompact objects and compact objects within such toposes and…

Category Theory · Mathematics 2021-01-12 Morgan Rogers

We define a tensor product of linear sites, and a resulting tensor product of Grothendieck categories based upon their representations as categories of linear sheaves. We show that our tensor product is a special case of the tensor product…

Category Theory · Mathematics 2017-03-16 Wendy Lowen , Julia Ramos González , Boris Shoikhet

The first goal of this paper is to provide an abstract framework in which to formulate and study local duality in various algebraic and topological contexts. For any stable $\infty$-category $\mathcal{C}$ together with a collection of…

Algebraic Topology · Mathematics 2019-01-23 Tobias Barthel , Drew Heard , Gabriel Valenzuela

The Grothendieck construction establishes an equivalence between fibrations, a.k.a. fibred categories, and indexed categories, and is one of the fundamental results of category theory. Cockett and Cruttwell introduced the notion of…

Category Theory · Mathematics 2025-07-30 Marcello Lanfranchi

We demonstrate that categories of continuous actions of topological monoids on discrete spaces are Grothendieck toposes. We exhibit properties of these toposes, giving a solution to the corresponding Morita-equivalence problem. We…

Category Theory · Mathematics 2024-08-07 Morgan Rogers

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 present an approach to measure theory using the theory of locales. This includes concrete constructions of measure algebras associated to Radon measures, such as the Lebesgue measure on $\mathbb{R}^n$, via Grothendieck topologies…

General Topology · Mathematics 2025-10-23 Georg Lehner

In this article we discuss local aspects of 2-functors defined on the path 2-groupoid of a smooth manifold; in particular, local trivializations and descent data. This is a contribution to a project that provides an axiomatic formulation of…

General Topology · Mathematics 2017-02-01 Urs Schreiber , Konrad Waldorf

We study tangent spaces in the setting of diffeological spaces. Several distinct tangent functors have been introduced, each of which extends the classical tangent functor from smooth manifolds. In this paper, we construct infinitely many…

Algebraic Topology · Mathematics 2025-11-25 Masaki Taho