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We prove an ambidexterity result for $\infty$-categories of $\infty$-categories admitting a collection of colimits. This unifies and extends two known phenomena: the identification of limits and colimits of presentable $\infty$-categories…

Category Theory · Mathematics 2026-03-12 Shay Ben-Moshe

In previous work, we showed that there are appropriate model category structures on the category of simplicial categories and on the category of Segal precategories, and that they are Quillen equivalent to one another and to Rezk's complete…

Algebraic Topology · Mathematics 2013-01-04 Julia E. Bergner

In previous work by the first two authors, Frobenius and commutative algebra objects in the category of spans of sets were characterized in terms of simplicial sets satisfying certain properties. In this paper, we find a similar…

Category Theory · Mathematics 2024-09-10 Ivan Contreras , Rajan Amit Mehta , Walker H. Stern

Let $\mathcal{C}$ be a $k$-linear category with split idempotents, and $\Sigma:\mathcal{C}\rightarrow\mathcal{C}$ an automorphism. We show that there is an $n$-angulated structure on $(\mathcal{C},\Sigma)$ under certain conditions. As an…

Representation Theory · Mathematics 2015-09-22 Zengqiang Lin

We introduce the notions of multiplier C*-category and continuous bundle of C*-categories, as the categorical analogues of the corresponding C*-algebraic notions. Every symmetric tensor C*-category with conjugates is a continuous bundle of…

Category Theory · Mathematics 2011-11-21 Ezio Vasselli

A duality between the category of convex spaces and measurable spaces arises from the existence of the unit interval, which is an object in both these categories. The full subcategory of the category of convex spaces, consisting of just the…

Category Theory · Mathematics 2017-07-04 Kirk Sturtz

In a bicategory of spans (an example of a 'generic bicategory') the factorization of a span (s,t) as the span (s,1) followed by (1,t) satisfies a simple universal property with respect to all factorizations in terms of the generic…

Category Theory · Mathematics 2020-02-25 Charles Walker

Both simplicial sets and simplicial spaces are used pervasively in homotopy theory as presentations of spaces, where in both cases we extract the "underlying space" by taking geometric realization. We have a good handle on the category of…

Algebraic Topology · Mathematics 2015-10-20 Aaron Mazel-Gee

We prove a categorical duality between a class of abstract algebras of partial functions and a class of (small) topological categories. The algebras are the isomorphs of collections of partial functions closed under the operations of…

Rings and Algebras · Mathematics 2021-09-28 Brett McLean

We introduce rigid algebras, a generalization of rigid categories to arbitrary symmetric monoidal $(\infty,2)$-categories. We develop their general theory, showing in particular that the a priori $(\infty,2)$-category of rigid algebras is…

Category Theory · Mathematics 2026-05-25 Leor Neuhauser

We provide two representations of the Segal category $\mathcal{X}$ modeling natural phenomena, the first one being based on the concept of micro-reversibility, producing a long sequence $\Sigma$ of categories as a resolution of…

Category Theory · Mathematics 2026-01-13 Renaud Gauthier

We consider three notions of divisibility in the Cuntz semigroup of a C*-algebra, and show how they reflect properties of the C*-algebra. We develop methods to construct (simple and non-simple) C*-algebras with specific divisibility…

Operator Algebras · Mathematics 2014-02-26 Leonel Robert , Mikael Rordam

We prove that the set of concordance classes of sections of an infinity-sheaf on a manifold is representable, extending a theorem of Madsen and Weiss. This is reminiscent of an h-principle in which the role of isotopy is played by…

Algebraic Topology · Mathematics 2025-02-26 Daniel Berwick-Evans , Pedro Boavida de Brito , Dmitri Pavlov

As an example of the categorical apparatus of pseudo algebras over 2-theories, we show that pseudo algebras over the 2-theory of categories can be viewed as pseudo double categories with folding or as appropriate 2-functors into…

Category Theory · Mathematics 2011-11-09 Thomas M. Fiore

Waldhausen's $S_\bullet$-construction gives a way to define the algebraic $K$-theory space of a category with cofibrations. Specifically, the $K$-theory space of a category with cofibrations $\mathcal{C}$ can be defined as the loop space of…

Algebraic Topology · Mathematics 2024-05-21 Tanner Nathan Carawan

We show that complete Segal spaces and Segal categories are Quillen equivalent to quasi-categories.

Algebraic Topology · Mathematics 2007-05-23 Andre Joyal , Myles Tierney

Starting from a description of various generalized function algebras based on sequence spaces, we develop the general framework for considering linear problems with singular coefficients or non linear problems. Therefore, we prove…

Functional Analysis · Mathematics 2007-05-23 Antoine Delcroix , Maximilian F. Hasler , Stevan Pilipović , Vincent Valmorin

Building on work by Fiore-Pronk-Paoli, we construct four model structures on the category of double categories, each modeling one of the following: simplicial spaces, Segal spaces, $(\infty,1)$-categories, and $\infty$-groupoids.…

Algebraic Topology · Mathematics 2024-12-23 Léonard Guetta , Lyne Moser

In this paper, we compare several functors which take simplicial categories or model categories to complete Segal spaces, which are particularly nice simplicial spaces which, like simplicial categories, can be considered to be models for…

Algebraic Topology · Mathematics 2007-10-11 Julia E. Bergner

For an associative algebra $A$ with a simple module $M$ with trivial endomorphisms and trivial annihilator we verify the countable separation property (CSP), i.e. we prove that there exists a list of nonzero elements $a_1, a_2,\ldots$ of…

Rings and Algebras · Mathematics 2025-10-30 Alexey Petukhov