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The main purpose of this paper is to give a new definition for the notion of group-groupoid. Also, several basic properties of group-groupoids are established.

Group Theory · Mathematics 2015-12-31 Mihai Ivan

A general model for geometric structures on differentiable manifolds is obtained by deforming infinitesimal symmetries. Specifically, this model consists of a Lie algebroid, equipped with an affine connection compatible with the Lie…

Differential Geometry · Mathematics 2012-03-07 Anthony D. Blaom

For a couple of associative algebras we define the notion of their double and give a set of examples. Also, we discuss applications of such doubles to representation theory of certain quantum algebras and to a new type of Noncommutative…

Quantum Algebra · Mathematics 2020-10-28 Dimitri Gurevich , Pavel Saponov

In this note we give a precise statement and a detailed proof for reconstruction problem of weak bialgebra maps. As an application we characterize indecomposability of weak algebras in categorical setting.

Rings and Algebras · Mathematics 2020-03-02 Michihisa Wakui

We show how one can do algebraic geometry with respect to the category of simplicial objects in an exact category. As a biproduct, we get a theory of derived analytic geometry.

Algebraic Geometry · Mathematics 2024-05-14 Oren Ben-Bassat , Jack Kelly , Kobi Kremnizer

Physicists showed that the generating function of orbifold elliptic genera of symmetric orbifolds can be written as an infinite product. We show that there exists a geometric factorization on space level behind this infinite product formula…

Algebraic Topology · Mathematics 2014-10-01 Hirotaka Tamanoi

We give a new characterization of partial groups as a subcategory of symmetric (simplicial) sets. This subcategory has an explicit reflection, which permits one to compute colimits in the category of partial groups. We also introduce the…

Group Theory · Mathematics 2025-03-10 Philip Hackney , Justin Lynd

An equivariant topological field theory is defined on a cobordism category of manifolds with principal fiber bundles for a fixed (finite) structure group. We provide a geometric construction which for any given morphism $G \to H$ of finite…

Quantum Algebra · Mathematics 2018-10-22 Christoph Schweigert , Lukas Woike

We analyze and compare different dynamical systems and groupoids which can be obtained from projection point patterns. We define the cohomology of a point pattern as the cocycle cohomology of the pattern groupoid. We describe this…

Algebraic Topology · Mathematics 2007-05-23 Alan Forrest , John Hunton , Johannes Kellendonk

2-stratifolds are a generalization of 2-manifolds in that there are disjoint simple closed curves where several sheets meet. They arise in the study of categorical invariants of 3-manifolds and may have applications to topological data…

Geometric Topology · Mathematics 2015-05-14 J. C. Gómez-Larrañaga , F. González-Acuña , Wolfgang Heil

Orbifolding two-dimensional quantum field theories by a symmetry group can involve a choice of discrete torsion. We apply the general formalism of `orbifolding defects' to study and elucidate discrete torsion for topological field theories.…

High Energy Physics - Theory · Physics 2015-03-24 Ilka Brunner , Nils Carqueville , Daniel Plencner

We study toroidal orbifold models with topologically invariant terms in the path integral formalism and give physical interpretations of the terms from an operator formalism point of view. We briefly discuss a possibility of a new class of…

High Energy Physics - Theory · Physics 2009-10-28 M. Sakamoto , M. Tachibana

We define the orbit category for transitive topological groupoids and their equivariant CW-complexes. By using these constructions we define equivariant Bredon homology and cohomology for actions of transitive topological groupoids. We show…

Algebraic Topology · Mathematics 2019-11-11 Carla Farsi , Laura Scull , Jordan Watts

The aim of this paper is to provide a definition of groupoid and cogroupoid internal to a category which makes use of only one object and morphisms, in contrast with the two object approach commonly found in the literature. We will give…

Category Theory · Mathematics 2013-05-14 Luiz Henrique P. Pêgas

We use rewriting systems to spell out cup-products in the (twisted) cohomology groups of a product of surface groups. This allows us to detect a non-trivial obstruction bounding from below the effective topological complexity of an…

Algebraic Topology · Mathematics 2020-03-04 Natalia Cadavid-Aguilar , Jesús González

In this paper we classify the closed orientable manifolds of arbitrary dimension.

General Mathematics · Mathematics 2007-05-23 Igor Bayak

We characterize vertex algebras (in a suitable sense) as algebras over a certain graded co-operad. We also discuss some examples and categorical implications of this characterization.

Rings and Algebras · Mathematics 2010-06-02 Ruthi Hortsch , Igor Kriz , Ales Pultr

We introduce an alternative formalization of curved spaces in which the concept of a pointwise affine space, as defined here, replaces that of a manifold. New or modified definitions of familiar notions from differential geometry such as…

Differential Geometry · Mathematics 2025-09-09 Dan Jonsson

This note shows that the orbifold Jacobian algebra associated to each invertible polynomial defining an exceptional unimodal singularity is isomorphic to the (usual) Jacobian algebra of the Berglund-H\"{u}bsch transform of an invertible…

Algebraic Geometry · Mathematics 2017-02-10 Alexey Basalaev , Atsushi Takahashi , Elisabeth Werner

After embedding the objects quasifolds into the category {Diffeology}, we associate a C*-agebra with every atlas of any quasifold, and show how different atlases give Morita equivalent algebras. This builds a new bridge between diffeology…

Differential Geometry · Mathematics 2022-10-25 Patrick Iglesias-Zemmour , Elisa Prato