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Categorification is the process of finding category-theoretic analogs of set-theoretic concepts by replacing sets with categories, functions with functors, and equations between functions by natural isomorphisms between functors, which in…

Quantum Algebra · Mathematics 2014-11-18 John C. Baez , James Dolan

The category of crossed complexes gives an algebraic model of CW-complexes and cellular maps. Free crossed resolutions of groups contain information on a presentation of the group as well as higher homological information. We relate this to…

Algebraic Topology · Mathematics 2021-06-22 Ronald Brown , Emma J. Moore , Timothy Porter , Christopher D. Wensley

We define Anderson-Brown-Cisinski (ABC) cofibration categories, and construct homotopy colimits of diagrams of objects in ABC cofibration categories. Homotopy colimits for Quillen model categories are obtained as a particular case. We…

Algebraic Topology · Mathematics 2009-02-08 Andrei Radulescu-Banu

We give an explicit description of the free objects in the quasivariety of adequate semigroups, as sets of labelled directed trees under a natural combinatorial multiplication. The morphisms of the free adequate semigroup onto the free…

Rings and Algebras · Mathematics 2009-05-08 Mark Kambites

Given a simplicial idempotent augmented endofunctor $F$ on a simplicial combinatorial model category $M$, under the assumption of Vopenka's principle, we exhibit a set $A$ of cofibrant objects in $M$ such that $F$ is equivalent to $\CW_A$,…

Algebraic Topology · Mathematics 2007-05-23 Boris Chorny

We introduce the concept of a pants decomposition for a finitely generated free group and construct the corresponding pants graph. A pants decomposition of a free group leads to the formation of a simplicial graph, referred to as the pants…

Group Theory · Mathematics 2026-04-20 Donggyun Seo

We start from any small strict monoidal braided Ab-category and extend it to a monoidal nonstrict braided Ab-category which contains braided bialgebras. The objects of the original category turn out to be modules for these bialgebras

Algebraic Topology · Mathematics 2010-07-02 Raul A. Perez , Carlos Prieto

In this article, we construct a cofibrantly generated model structure on the category of spaces stratified over a fixed poset, and show that it is Quillen-equivalent to a category of diagrams of simplicial sets. Then, considering all those…

Algebraic Topology · Mathematics 2021-03-10 Sylvain Douteau

We introduce the notion of pie algebra for a 2-monad, these bearing the same relationship to the flexible and semiflexible algebras as pie limits do to flexible and semiflexible ones. We see that in many cases, the pie algebras are…

Category Theory · Mathematics 2022-01-31 John Bourke , Richard Garner

We show that under mild conditions on the monoidal base category $\mathcal V$, the category ${\sf VHopf}$ of Hopf $\mathcal V$-categories is locally presentable and deduce the existence of free and cofree Hopf categories. We also provide an…

Category Theory · Mathematics 2024-05-01 Paul Großkopf , Joost Vercruysse

We introduce a notion of signature whose sorts form a direct category, and study computads for such signatures. Algebras for such a signature are presheaves with an interpretation of every function symbol of the signature, and we describe…

Category Theory · Mathematics 2024-11-06 Ioannis Markakis

In this paper, we introduce the cofibrant derived category of a group algebra $kG$ and study its relation to the derived category of $kG$. We also define the cofibrant singularity category of $kG$, whose triviality characterizes the…

Category Theory · Mathematics 2025-12-30 Ioannis Emmanouil , Wei Ren

We define biprops as a generalization of coloured props and of symmetric weak multicategories. These are bicategories whose objects form a free monoid. They are equipped with some structure resembling a symmetric strict tensor product. We…

Category Theory · Mathematics 2026-04-21 Volodymyr Lyubashenko

We give a counterexample to a conjecture by Miasnikov, Ventura and Weil, stating that an extension of free groups is algebraic if and only if the corresponding morphism of their core graphs is onto, for every basis of the ambient group. In…

Group Theory · Mathematics 2021-01-05 Noam Kolodner

We consider the canonical pseudodistributive law between various free limit completion pseudomonads and the free coproduct completion pseudomonad. When the class of limits includes pullbacks, we show that this consideration leads to notions…

Category Theory · Mathematics 2024-06-13 Fernando Lucatelli Nunes , Rui Prezado , Matthijs Vákár

This paper is devoted to the proof of the property of order separability for free product of free groups with maximal cyclic amalgamated subgroups.

Group Theory · Mathematics 2010-07-09 Vladimir V. Yedynak

We describe the category of homotopy coalgebras, concentrating on properties of relatively cofree homotopy coalgebras, morphisms and coderivations from an ordinary coalgebra to a relatively cofree homotopy coalgebra, morphisms and…

Category Theory · Mathematics 2014-02-04 Volodymyr Lyubashenko

In this paper we define Martin-L\"{o}f complexes to be algebras for monads on the category of (reflexive) globular sets which freely add cells in accordance with the rules of intensional Martin-L\"{o}f type theory. We then study the…

Logic · Mathematics 2012-05-25 Steve Awodey , Pieter Hofstra , Michael A. Warren

We investigate categories in which products distribute over coproducts, a structure we call doubly-infinitary distributive categories. Through a range of examples, we explore how this notion relates to established concepts such as…

Category Theory · Mathematics 2025-10-15 Fernando Lucatelli Nunes , Matthijs Vákár

In this thesis, we develop the theory of bifibrations of polycategories. We start by studying how to express certain categorical structures as universal properties by generalising the shape of morphism. We call this phenomenon…

Category Theory · Mathematics 2023-05-25 Nicolas Blanco