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Given a bicategory C and a family W of arrows of C, we give conditions on the pair (C,W) that allow us to construct the bicategorical localization with respect to W by dealing only with the 2-cells, that is without adding objects or arrows…

Category Theory · Mathematics 2021-02-05 M. E. Descotte , E. J. Dubuc , M. Szyld

Lifts of categorical diagrams $D\colon\mathsf{J}\to\mathsf{X}$ against discrete opfibrations $\pi\colon\mathsf{E}\to\mathsf{X}$ can be interpreted as presenting solutions to systems of equations. With this interpretation in mind, it is…

Category Theory · Mathematics 2024-01-24 Kevin Arlin , James Fairbanks , Tim Hosgood , Evan Patterson

In this paper, we define indexed type theories which are related to indexed ($\infty$-)categories in the same way as (homotopy) type theories are related to ($\infty$-)categories. We define several standard constructions for such theories…

Category Theory · Mathematics 2023-06-22 Valery Isaev

We introduce the notion of noncompact (partial) silting and (partial) tilting sets and objects in any triangulated category D with arbitrary (set-indexed) coproducts. We show that equivalence classes of partial silting sets are in bijection…

Representation Theory · Mathematics 2018-07-05 Pedro Nicolas , Manuel Saorin , Alexandra Zvonareva

We provide descriptions of the derived categories of degree $d$ hypersurface fibrations which generalize a result of Kuznetsov for quadric fibrations and give a relative version of a well-known theorem of Orlov. Using a local generator and…

Algebraic Geometry · Mathematics 2014-09-22 Matthew Ballard , Dragos Deliu , David Favero , M. Umut Isik , Ludmil Katzarkov

The embedded cobordism category under study in this paper generalizes the category of conformal surfaces, introduced by G. Segal in order to formalize the concept of field theories. Our main result identifies the homotopy type of the…

Algebraic Topology · Mathematics 2010-09-23 Soren Galatius , Ib Madsen , Ulrike Tillmann , Michael Weiss

Several possible presentations for the homotopy theory of (non-hypercomplete) $\infty$-stacks on a classical site S are discussed. In particular, it is shown that an elegant combinatorial description in terms of diagrams in S exists,…

Algebraic Topology · Mathematics 2022-04-07 Fritz Hörmann

Given a functor $T:C \to D$ carrying a class of morphisms $S\subset C$ into a class $S'\subset D$, we give sufficient conditions in order that $T$ induces an equivalence on the localised categories. These conditions are in the spirit of…

Algebraic Geometry · Mathematics 2010-09-13 Bruno Kahn , R. Sujatha

Combinatorial model categories were introduced by J. H. Smith as model categories which are locally presentable and cofibrantly generated. He has not published his results yet but proofs of some of them were presented by T. Beke or D.…

Category Theory · Mathematics 2012-05-02 J. Rosicky

This work introduces a general theory of universal pseudomorphisms and develops their connection to diagrammatic coherence. The main results give hypotheses under which pseudomorphism coherence is equivalent to the coherence theory of…

Category Theory · Mathematics 2025-07-02 Nick Gurski , Niles Johnson

If $D$ is a Reedy category and $M$ is a model category, the category $M^{D}$ of $D$-diagrams in $M$ is a model category under the Reedy model category structure. If $C \to D$ is a Reedy functor between Reedy categories, then there is an…

Algebraic Topology · Mathematics 2019-03-18 Philip S. Hirschhorn , Ismar Volic

Constructing and manipulating homotopy types from categorical input data has been an important theme in algebraic topology for decades. Every category gives rise to a `classifying space', the geometric realization of the nerve. Up to weak…

Algebraic Topology · Mathematics 2019-10-30 Stefan Schwede

If $\mathbf{C}$ is a category with pullbacks then there is a bicategory with the same objects as $\mathbf{C}$, spans as morphisms, and maps of spans as 2-morphisms, as shown by Benabou. Fong has developed a theory of "decorated" cospans,…

Category Theory · Mathematics 2017-09-20 Kenny Courser

The relative cell complexes with respect to a generating set of cofibrations are an important class of morphisms in any model structure. In the particular case of the standard (algebraic) model structure on $\textbf{Top}$, we give a new…

Category Theory · Mathematics 2013-04-01 Thomas Athorne

In previous work, we introduce an axiomatic framework within which to prove theorems about many varieties of infinite-dimensional categories simultaneously. In this paper, we establish criteria implying that an $\infty$-category - for…

Category Theory · Mathematics 2020-07-17 Emily Riehl , Dominic Verity

We define a new model structure on the category of small categories, which is intimately related to the notion of coverings and fundamental groups of small categories. Fibrant objects in the model structure coincide with groupoids, and the…

Category Theory · Mathematics 2012-05-08 Kohei Tanaka

Diagrammatic sets are presheaves on a rich category of shapes, whose definition is motivated by combinatorial topology and higher-dimensional diagram rewriting. These shapes include representatives of oriented simplices, cubes, and positive…

Algebraic Topology · Mathematics 2024-07-16 Clémence Chanavat , Amar Hadzihasanovic

2-Theories are a canonical way of describing categories with extra structure. 2-theory-morphisms are used when discussing how one structure can be replaced with another structure. This is central to categorical coherence theory. We place a…

Category Theory · Mathematics 2007-05-23 Noson S. Yanofsky

Let X be a quasi-compact scheme, equipped with an open covering by affine schemes. A quasi-coherent sheaf on X gives rise, by taking sections over the covering sets, to a diagram of modules over the various coordinate rings. The resulting…

K-Theory and Homology · Mathematics 2010-07-30 Thomas Huettemann

We study 2-monads and their algebras using a Cat-enriched version of Quillen model categories, emphasizing the parallels between the homotopical and 2-categorical points of view. Every 2-category with finite limits and colimits has a…

Category Theory · Mathematics 2010-09-10 Stephen Lack