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A diagram of groupoid correspondences is a homomorphism to the bicategory of \'etale groupoid correspondences. We study examples of such diagrams, including complexes of groups and self-similar higher-rank graphs. We encode the diagram in a…

Category Theory · Mathematics 2022-03-24 Ralf Meyer

We give a completely formalized definition of a notion of " general manifold ". It turns out that " gluing data " form an equivalence-partially ordered set (e-pos), which is a special instance of an ordered groupoid. We state and prove…

Category Theory · Mathematics 2016-05-26 Wolfgang Bertram

When G is a finite abelian group, we define G-spans of groupoids and their associated matrices with entries in the group ring QG and show that composition of spans corresponds to multiplication of matrices.

Category Theory · Mathematics 2026-03-24 Joachim Kock , Jesper M. Møller

We describe a pretorsion theory in the category $Cat$ of small categories: the torsion objects are the groupoids, while the torsion-free objects are the skeletal categories, i.e., those categories in which every isomorphism is an…

Category Theory · Mathematics 2023-08-09 Francis Borceux , Federico Campanini , Marino Gran , Walter Tholen

Clones are specializations of operads forming powerful instruments to describe varieties of algebras wherein repeating variables are allowed in their equations. They allow us in this way to realize and study a large range of algebraic…

Combinatorics · Mathematics 2026-04-08 Samuele Giraudo

Regardless of its environment, the category of internal groupoids is shown to be equivalent to the full subcategory of involutive-2-links that are unital and associative. The new notion of involutive-2-link originates from the study of…

Category Theory · Mathematics 2023-05-24 Nelson Martins-Ferreira

Motivated by some alternatives to the classical logical model of boolean algebra, this paper deals with algebraic structures which extend skew lattices by locally invertible elements. Following the meme of the Ehresmann-Schein-Nambooripad…

Group Theory · Mathematics 2021-01-07 D. G. FitzGerald

In this paper we discuss generalized group, provides some interesting examples. Further we introduce a generalized module as a module like structure obtained from a generalized group and discuss some of its properties and we also describes…

General Mathematics · Mathematics 2020-10-13 P. G. Romeo , Sneha K K

We explore the category of internal categories in the usual category of (right) group-sets, whose objects are referred to as categorified group-sets. More precisely, we develop a new Burnside theory, where the equivalence relation between…

Group Theory · Mathematics 2019-06-18 Laiachi El Kaoutit , Leonardo Spinosa

The aim of this paper is to describe the definitions and main properties of three generalizations of the group concept, namely: groupoid, generalized group and almost groupoid. Some constructions of these algebraic structures and…

Group Theory · Mathematics 2025-11-03 Gheorghe Ivan

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

Some basic notions and results in Topological Dynamics are extended to continuous groupoid actions in topological spaces. We focus mainly on recurrence properties. Besides results that are analogous to the classical case of group actions,…

Dynamical Systems · Mathematics 2022-12-01 Felipe Flores , Marius Mantoiu

In this paper, we consider the groupoidification of the fermion algebra. We construct a groupoid as the categorical analogues of the fermionic Fock space, and the creation and annihilation operators correspond to spans of groupoids. The…

Mathematical Physics · Physics 2020-11-20 Wei Chen , Bing-Sheng Lin

In an enriched setting, we show that higher groupoids and higher categories form categories of fibrant objects. The nerve of a differential graded algebra is a higher category in the category of algebraic varieties, where covers are defined…

Algebraic Geometry · Mathematics 2018-01-16 Kai Behrend , Ezra Getzler

A subunit in a monoidal category is a subobject of the monoidal unit for which a canonical morphism is invertible. They correspond to open subsets of a base topological space in categories such as those of sheaves or Hilbert modules. We…

Category Theory · Mathematics 2020-06-22 Pau Enrique Moliner , Chris Heunen , Sean Tull

It is well-known that reduced smooth orbifolds and proper effective foliation Lie groupoids form equivalent categories. However, for certain recent lines of research, equivalence of categories is not sufficient. We propose a notion of maps…

Geometric Topology · Mathematics 2015-09-10 Anke D. Pohl

We introduce some deformations of the biset category and prove a semisimplicity property. We also consider another group category, called the subgroup category, whose morphisms are subgroups of direct products, the composition being star…

Representation Theory · Mathematics 2020-01-09 Laurence Barker , İsmail Alperen Öğüt

We consider a version of the notion of F-inverse semigroup (studied in the algebraic theory of inverse semigroups). We point out that an action of such an inverse semigroup on a locally compact space has associated a natural groupoid…

funct-an · Mathematics 2008-02-03 Alexandru Nica

A geometric grid class consists of those permutations that can be drawn on a specified set of line segments of slope \pm1 arranged in a rectangular pattern governed by a matrix. Using a mixture of geometric and language theoretic methods,…

Combinatorics · Mathematics 2012-02-06 Michael H. Albert , M. D. Atkinson , Mathilde Bouvel , Nik Ruškuc , Vincent Vatter

A groupoid is a small category in which all morphisms are isomorphisms. An inductive groupoid is a specialised groupoid whose object set is a regular biordered set and the morphisms admit a partial order. A normal category is a specialised…

Category Theory · Mathematics 2021-09-14 P. A. Azeef Muhammed , Mikhail V. Volkov