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Recently Riehl and Verity have introduced $\infty$-cosmoi, which are certain simplicially enriched categories with additional structure. In this paper we investigate those $\infty$-cosmoi which are in fact $2$-categories; we shall refer to…

Category Theory · Mathematics 2025-09-15 John Bourke , Stephen Lack

This paper defines double fibrations (fibrations of double categories) and describes their key examples and properties. In particular, it shows how double fibrations relate to existing fibrational notions such as monoidal fibrations and…

Category Theory · Mathematics 2022-05-31 Geoffrey Cruttwell , Michael Lambert , Dorette Pronk , Martin Szyld

The goal of this paper is to provide the last equivalence needed in order to identify all known models for $(\infty,2)$-categories. We do this by showing that Verity's model of saturated $2$-trivial complicial sets is equivalent to Lurie's…

Algebraic Topology · Mathematics 2022-03-02 Andrea Gagna , Yonatan Harpaz , Edoardo Lanari

In this work we provide a model-independent notion of local fibrations of $(\infty,2)$-categories which generalises the well-known theory of locally coCartesian fibrations of $(\infty,1)$-categories. Based on previous work, we construct a…

Algebraic Topology · Mathematics 2023-05-03 F. Abellán

We set the foundations of a theory of Grothendieck $(\infty,2)$-topoi based on the notion of fibrational descent, which axiomatizes both the existence of a classifying object for fibrations internal to an $(\infty,2)$-category as well as…

Category Theory · Mathematics 2024-10-04 Fernando Abellán , Louis Martini

In this work, we conclude our study of fibred $\infty$-bicategories by providing a Grothendieck construction in this setting. Given a scaled simplicial set $S$ (which need not be fibrant) we construct a 2-categorical version of Lurie's…

Algebraic Topology · Mathematics 2023-04-14 Fernando Abellán , Walker H. Stern

We study limits in 2-categories whose objects are categories with extra structure and whose morphisms are functors preserving the structure only up to a coherent comparison map, which may or may not be required to be invertible. This is…

Category Theory · Mathematics 2012-02-20 Stephen Lack , Michael Shulman

The unstraightening construction due to Lurie establishes an equivalence between presheaves and fibrations, using one prominent model of $(\infty,1)$-categories, namely quasi-categories. In this work we generalize this result by proving…

Category Theory · Mathematics 2025-06-06 Nima Rasekh

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

In this paper, we obtain two extension theorems for cohomology classes and holomorphic sections defined on analytic subvarieties, which are defined as the supports of the quotient sheaves of multiplier ideal sheaves of…

Complex Variables · Mathematics 2019-09-20 Xiangyu Zhou , Langfeng Zhu

In this paper, we provide a notion of $\infty$-bicategories fibred in $\infty$-bicategories which we call 2-Cartesian fibrations. Our definition is formulated using the language of marked biscaled simplicial sets: Those are scaled…

Algebraic Topology · Mathematics 2021-06-08 Fernando Abellán García , Walker H. Stern

We study four types of (co)cartesian fibrations of $\infty$-bicategories over a given base $\mathcal{B}$, and prove that they encode the four variance flavors of $\mathcal{B}$-indexed diagrams of $\infty$-categories. We then use this…

Algebraic Topology · Mathematics 2021-03-11 Andrea Gagna , Yonatan Harpaz , Edoardo Lanari

This paper is concerned with developing a 2-dimensional analogue of the notion of an ordinary discrete fibration. A definition is proposed, and it is shown that such discrete 2-fibrations correspond via a 2-equivalence to certain…

Category Theory · Mathematics 2020-01-31 Michael Lambert

In this paper we study a 2-dimensional version of Quillen's homotopy category construction. Given a category $\mathscr{A}$ and a class of morphisms $\Sigma \subset \mathscr{A}$ containing the identities, we construct a 2-category…

Category Theory · Mathematics 2023-02-28 Eduardo J. Dubuc , Jaqueline Girabel

In this short expository note, we discuss, with plenty of examples, the bestiary of fibrations in quasicategory theory. We underscore the simplicity and clarity of the constructions these fibrations make available to end-users of higher…

Category Theory · Mathematics 2016-08-15 Clark Barwick , Jay Shah

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

We use Cisinski's machinery to construct and study model structures on the category of simplicial sets whose classes of fibrant objects generalize quasi-categories. We identify a lifting condition which captures the homotopical behavior of…

Algebraic Topology · Mathematics 2025-04-02 Matthew Feller

We construct a model structure on the category of cubical sets with connections whose cofibrations are the monomorphisms and whose fibrant objects are defined by the right lifting property with respect to inner open boxes, the cubical…

Algebraic Topology · Mathematics 2022-02-08 Brandon Doherty , Chris Kapulkin , Zachery Lindsey , Christian Sattler

In a recent paper we introduced a much weaker and easy to verify structure than a model category, which we called a "weak fibration category". We further showed that a small weak fibration category can be "completed" into a full model…

Category Theory · Mathematics 2015-07-03 Ilan Barnea , Tomer M. Schlank

We introduce group-theoretical fusion 2-categories, a strong categorification of the notion of a group-theoretical fusion 1-category. Physically speaking, such fusion 2-categories arise by gauging subgroups of a global symmetry. We show…

Category Theory · Mathematics 2025-02-24 Thibault D. Décoppet , Matthew Yu