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Let $G$ be a finite group. In this paper, we first introduce a new notion, so-called the Mackey double category of $G$. Then we prove that the category of Mackey double categories and the category of Mackey functors of $G$ are equivalent.

Group Theory · Mathematics 2026-03-18 Mawei Wu

We provide a framework for abstract reconstruction problems using the $K$-theory of categories with covering families, which we then apply to reformulate the edge reconstruction conjecture in graph theory. Along the way, we state some…

K-Theory and Homology · Mathematics 2025-06-17 Maxine E. Calle , Julian J. Gould

We introduce Hopf categories enriched over braided monoidal categories. The notion is linked to several recently developed notions in Hopf algebra theory, such as Hopf group (co)algebras, weak Hopf algebras and duoidal categories. We…

Quantum Algebra · Mathematics 2017-01-02 E. Batista , S. Caenepeel , J. Vercruysse

We show that the positive zoom complexes, with fairly natural morphisms, form a dual category to the category of positive opetopes with contraction epimorphisms. We also show how this duality can be extended to opetopic cardinals.

Category Theory · Mathematics 2023-04-18 Marek Zawadowski

We study extension theorems for Lipschitz-type operators acting on metric spaces and with values on spaces of integrable functions. Pointwise domination is not a natural feature of such spaces, and so almost everywhere inequalities and…

Functional Analysis · Mathematics 2019-10-02 W. V. Cavalcante , P. Rueda , E. A. Sánchez-Pérez

In this paper we establish Koszul duality type results in the setting of chain complexes in exact categories. In particular we prove generalisations of Vallette's cooperadic Koszul duality theorem, and operadic Koszul duality along the…

Category Theory · Mathematics 2023-12-29 Jack Kelly

Using methods of KK-theory, we generalize Poincare duality to the framework of twisted K-theory.

K-Theory and Homology · Mathematics 2007-05-23 Jean-Louis Tu

We give a geometric model for a tube category in terms of homotopy classes of oriented arcs in an annulus with marked points on its boundary. In particular, we interpret the dimensions of extension groups of degree 1 between indecomposable…

Representation Theory · Mathematics 2020-12-21 Karin Baur , Bethany Marsh

This is a condensed overview of the formal theory of monads in a 2-category. We also define two double categories of monads in a 2-category, extending Lack and Street's 2-categories of monads.

Category Theory · Mathematics 2026-05-06 Aaron David Fairbanks

In this paper we use topological techniques to construct generalized trace and modified dimension functions on ideals in certain ribbon categories. Examples of such ribbon categories naturally arise in representation theory where the usual…

Representation Theory · Mathematics 2010-01-08 Nathan Geer , Jonathan Kujawa , Bertrand Patureau-Mirand

In this paper we extend the concept of dinaturality to the setting of double categories. We introduce the dinatural versions of double-categorical transformations and modifications, and show that ordinary natural transformations and…

Category Theory · Mathematics 2026-03-04 Edward Morehouse

We initiate the study of derived functors in the setting of extriangulated categories. By using coends, we adapt Yoneda's theory of higher extensions to this framework. We show that, when there are enough projectives or enough injectives,…

Category Theory · Mathematics 2021-03-24 Mikhail Gorsky , Hiroyuki Nakaoka , Yann Palu

A classification is provided of functors, in particular polynomial ones, from a category with a zero object in which every object is a finite sum of copies of a generating object, into an abelian category. This classification is extended to…

Category Theory · Mathematics 2015-05-13 Qimh Richey Xantcha

We establish a functor $Kan$ from local Kan simplicial manifolds to weak Kan simplicial manifolds. It gives a solution to the problem of extending local Lie groupoids to Lie 2-groupoids.

Differential Geometry · Mathematics 2015-05-13 Chenchang Zhu

Any non-degenerate quadratic form over a Hilbertian field (e.g., a number field) is isomorphic to a scaled trace form. In this work we extend this result to more general fields. In particular, prosolvable and prime-to-p extensions of a…

Number Theory · Mathematics 2007-08-29 Lior Bary-Soroker , Dubi Kelmer

We prove that the period doubling operator has an expanding direction at the fixed point. We use the induced operator, a ``Perron-Frobenius type operator'', to study the linearization of the period doubling operator at its fixed point. We…

Dynamical Systems · Mathematics 2016-09-06 Yunping Jiang , Takehiko Morita , Dennis Sullivan

In this paper we introduce a description of ordered groupoids as a particular type of double categories. This enables us to turn Lawson's correspondence between ordered groupoids and left-cancellative categories into a biequivalence. We use…

Category Theory · Mathematics 2019-10-08 Darien DeWolf , Dorette Pronk

Fibrations over a category $B$, introduced to category theory by Grothendieck, encode pseudo-functors $B^{op} \rightsquigarrow {\bf Cat}$, while the special case of discrete fibrations encode presheaves $B^{op} \to {\bf Set}$. A two-sided…

Category Theory · Mathematics 2020-06-02 Fosco Loregian , Emily Riehl

In this paper we present background results in enriched category theory and enriched model category theory necessary for developing model categories of enriched functors suitable for doing functor calculus.

Algebraic Topology · Mathematics 2022-05-16 Lauren Bandklayder , Julia E. Bergner , Rhiannon Griffiths , Brenda Johnson , Rekha Santhanam

Generalizing Duality Theorem of V. V. Fedorchuk, we prove Stone-type duality theorems for the following four categories: all of them have as objects the locally compact Hausdorff spaces, and their morphisms are, respectively, the continuous…

General Topology · Mathematics 2007-10-01 Georgi Dobromirov Dimov
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