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If $\mathcal{C}$ is a category of algebras closed under finite direct products, and $M_\mathcal{C}$ the commutative monoid of isomorphism classes of members of $\mathcal{C},$ with operation induced by direct product, A.Tarski defined a…

Rings and Algebras · Mathematics 2026-04-28 George M. Bergman

We define a traced pseudomonoid as a pseudomonoid in a monoidal bicategory equipped with extra structure, giving a new characterisation of Cauchy complete traced monoidal categories as algebraic structures in $\mathbf{Prof}$, the monoidal…

Category Theory · Mathematics 2024-03-12 Nick Hu , Jamie Vicary

We show that on an infinite set, there exist no other precomplete clones closed under conjugation except those which contain all permutations. Since on base sets of some infinite cardinalities, in particular on countably infinite ones, the…

Rings and Algebras · Mathematics 2007-05-23 Michael Pinsker

We provide various ways to characterise $\Sigma$-pure-injective objects in a compactly generated triangulated category. These characterisations mimic analogous well-known results from the model theory of modules. The proof involves two…

Category Theory · Mathematics 2021-03-09 Raphael Bennett-Tennenhaus

We introduce a topology on the space of actions modulo weak equivalence finer than the one previously studied in the literature. We show that the product of actions is a continuous operation with respect to this topology, so that the space…

Dynamical Systems · Mathematics 2015-01-26 Peter Burton

This note proves the geodesic completeness of any compact manifold endowed with a linear connection such that the closure of its holonomy group is compact.

Differential Geometry · Mathematics 2015-12-22 Luis Aké Hau , Miguel Sánchez

In this paper we introduce the notion of weak operator and the theory of Yetter-Drinfeld modules over a weak braided Hopf algebra with invertible antipode in a strict monoidal category. We prove that the class of such objects constitutes a…

We introduce the notion of Whitehead sequence which is defined for a base category together with a system of abstract actions over it. In the classical case of groups and group actions the Whitehead sequences are precisely the…

Category Theory · Mathematics 2015-05-29 Nelson Martins-Ferreira

We show that, with some technical conditions, an abelian category can be embedded into the category of bimodules over a ring. The case of semisimple rigid monoidal categories is studied in more detail.

Category Theory · Mathematics 2007-05-23 Phung Ho Hai

We study actions of discrete groups on 2-categories. The motivating examples are actions on the 2-category of representations of finite tensor categories and their relation with the extension theory of tensor categories by groups.…

Quantum Algebra · Mathematics 2017-02-10 Eugenia Bernaschini , César Galindo , Martín Mombelli

This paper provides a comprehensive overview of some of the foundational properties of categories enriched over quantaloids, along with several new results. We demonstrate that the category whose objects are quantaloid-enriched categories…

Category Theory · Mathematics 2025-10-14 Javier Gutiérrez García , Ulrich Höhle

If $\mathcal{C}$ is a cocomplete monoidal category in which tensoring from both sides preserves coequalizers, then the category of monoids over $\mathcal{C}$ is cocomplete. The same holds if $\mathcal{C}$ has regular factorizations and…

Category Theory · Mathematics 2018-07-03 Hans-E. Porst

This article examines the three-way relationship between right coherency of a monoid $S$, solutions of equations over $S$-acts, and injectivity properties of $S$-acts. A monoid $S$ is right coherent if every finitely generated subact of…

Group Theory · Mathematics 2023-01-30 Yang Dandan , Victoria Gould

A near permutation of a set is a bijection between two cofinite subsets, modulo coincidence on smaller cofinite subsets. Near permutations of a set form its near symmetric group. In this monograph, we define near actions as homomorphisms…

Group Theory · Mathematics 2019-01-17 Yves Cornulier

Multiplier bimonoids (or bialgebras) in arbitrary braided monoidal categories are defined. They are shown to possess monoidal categories of comodules and modules. These facts are explained by the structures carried by their induced…

Quantum Algebra · Mathematics 2014-11-19 Gabriella Böhm , Stephen Lack

By restricting to a class of localic open groupoids $G$ which, similarly to Lie groupoids, possess appropriate covers $\widehat G\to G$ by \'etale groupoids, we extend results about groupoid actions and quantales that were previously proved…

Category Theory · Mathematics 2020-09-23 Juan Pablo Quijano , Pedro Resende

Recently, many authors have embraced the study of certain properties of modules such as projectivity, injectivity and flatness from an alternative point of view. Rather than saying a module has a certain property or not, each module is…

Commutative Algebra · Mathematics 2021-06-30 Houda Amzil , Driss Bennis , J. R. Garcia Rozas , Luis Oyonarte

In this paper, we identify some categorical structures in which one can model predicative formal systems: in other words, predicative analogues of the notion of a topos, with the aim of using sheaf models to interprete predicative formal…

Logic · Mathematics 2007-05-23 Benno van den Berg

Let $R$ be any associative ring with unity and $\mathcal{X}$ be a class of $R$-modules of closed under direct sum (and summands) and with extension closed. We prove that every complex has an $C(\mathcal{X^{*}})$-cover…

Rings and Algebras · Mathematics 2016-08-14 Tahire Özen , Emine Yıldırım

We study types of mapping classes which arise as a product of a given mapping class and powers of certain pure mapping classes. We derive an explicit constant depending only on a surface such that almost all above pure mapping classes give…

Geometric Topology · Mathematics 2017-01-06 Yohsuke Watanabe