English
Related papers

Related papers: Topoi with enough points and topological groupoids

200 papers

The aim of this article is to explain a philosophy for applying higher dimensional Seifert-van Kampen Theorems, and how the use of groupoids and strict higher groupoids resolves some foundational anomalies in algebraic topology at the…

Algebraic Topology · Mathematics 2020-12-04 Ronald Brown

In this paper, we classify finite categories with two objects such that one of the endomorphism monoids is a group. We prove that having a group on one side affects the structure of the other endomorphism monoid, and we prove that it is…

Category Theory · Mathematics 2022-10-04 Najwa Ghannoum , Carlos Simpson

We provide three functorial extensions of the equivalence between localic etale groupoids and their quantales. The main result is a biequivalence between the bicategory of localic etale groupoids, with bi-actions as 1-cells, and a…

Category Theory · Mathematics 2015-10-21 Pedro Resende

A candidate for the effective 2-topos is proposed and shown to include the effective 1-topos as its subcategory of 0-types.

Category Theory · Mathematics 2026-01-14 Steve Awodey , Jacopo Emmenegger

We show that every source connected Lie groupoid always has global bisections through any given point. This bisection can be chosen to be the multiplication of some exponentials as close as possible to a prescribed curve. The existence of…

Differential Geometry · Mathematics 2008-07-24 Z. Chen , Z. -J. Liu , D. -S. Zhong

v2: An additional assumption was added in Theorem 4.8. In order to show that a connected abelian group is admissible on the site of locally compact spaces we must in addition assume that it is locally topologically divisible. This condition…

Algebraic Topology · Mathematics 2018-11-28 Ulrich Bunke , Thomas Schick , Markus Spitzweck , Andreas Thom

In contrast to classical strongly continuous semigroups, the study of bi-continuous semigroups comes with some freedom in the properties of the associated locally convex topology. This paper aims to give minimal assumptions in order to…

Functional Analysis · Mathematics 2023-07-19 Karsten Kruse , Felix L. Schwenninger

We present a method of constructing monoidal, braided monoidal, and symmetric monoidal bicategories from corresponding types of monoidal double categories that satisfy a lifting condition. Many important monoidal bicategories arise…

Category Theory · Mathematics 2019-11-26 Linde Wester Hansen , Michael Shulman

Takahasi's theorem on chains of subgroups of bounded rank in a free group is generalized to several classes of semigroups. As an application, it is proved that the subsemigroups of periodic points are finitely generated and periodic orbits…

Group Theory · Mathematics 2015-04-02 Mário J. J. Branco , Gracinda M. S. Gomes , Pedro V. Silva

We study toposes of actions of monoids on sets. We begin with ordinary actions, producing a class of presheaf toposes which we characterize. As groundwork for considering topological monoids, we branch out into a study of supercompactly…

Category Theory · Mathematics 2021-12-21 Morgan Rogers

The concept of typed topological space is introduced, for which open sets in a topology on a finite set will be assigned types (from lattice). The neighborhood system of a point, the closure and the connectedness can be defined according to…

General Topology · Mathematics 2018-04-13 Wanjun Hu

We investigate the homology of ample Hausdorff groupoids. We establish that a number of notions of equivalence of groupoids appearing in the literature coincide for ample Hausdorff groupoids, and deduce that they all preserve groupoid…

Operator Algebras · Mathematics 2018-08-24 Carla Farsi , Alex Kumjian , David Pask , Aidan Sims

The paper establishes an equivalence between directed homotopy categories of (diagrams of) cubical sets and (diagrams of) directed topological spaces. This equivalence both lifts and extends an equivalence between classical homotopy…

Algebraic Topology · Mathematics 2026-02-02 Sanjeevi Krishnan

Elmendorf's Theorem states that the category of continuous actions of a topological group is a Grothendieck topos in the sense that it is equivalent to a category of sheaves on a site. This paper offers a 2-dimensional generalization by…

Category Theory · Mathematics 2019-11-14 Michael Lambert

We provide bicategorical analogs of several aspects of the notion of geometry in the sense of the theory of spectrum. We first introduce a notion of local right biadjoint, and prove it to be equivalent to a notion of bistable pseudofunctor,…

Category Theory · Mathematics 2021-11-19 Axel Osmond

We show that the topological full group of a Hausdorff ample groupoid with compact unit space coincides with the group of homotopy classes of invertible isometries in pseudofunction algebras associated with the groupoid. Moreover, if the…

Operator Algebras · Mathematics 2025-11-19 Eusebio Gardella , Mathias Palmstrøm , Hannes Thiel

We give a short, mostly elementary and self-contained proof of the classical result that the groups of diffeomorphisms, homeomorphisms, and homotopy equivalences of a surface have the same group of connected components.

General Topology · Mathematics 2009-08-18 Søren Kjærgaard Boldsen

This work contributes to clarifying several relationships between certain higher categorical structures and the homotopy type of their classifying spaces. Bicategories (in particular monoidal categories) have well understood simple…

Category Theory · Mathematics 2010-06-28 P. Carrasco , A. M. Cegarra , A. R. Garzón

D. K. Biss (Topology and its Applications 124 (2002) 355-371) introduced the topological fundamental group and presented some interesting basic properties of the notion. In this article we intend to extend the above notion to homotopy…

Algebraic Topology · Mathematics 2011-02-02 Helen Ghane , Zainab Hamed , Behrooz Mashayekhy , Hanieh Mirebrahimi

It is well-known that small categories have equivalent descriptions as partial monoids. We provide a formulation of partial monoid and partial monoid homomorphism involving $s$ and $t$ instead of identities and then following a recent…

Category Theory · Mathematics 2015-03-02 Rachel A. D. Martins