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In this paper, using the classical covering theory, we introduce a generalization of covering maps of a space $X$ with respect to a topology $\tau$ on the fundamental group of $X$. We show that the famous notions, covering, semicovering,…

Algebraic Topology · Mathematics 2026-02-24 Naghme Shahami , Behrooz Mashayekhy

We undertake a systematic study of the notion of fibration in the setting of abstract simplicial complexes, where the concept of `homotopy' has been replaced by that of `contiguity'. Then a fibration will be a simplicial map satisfying the…

Algebraic Topology · Mathematics 2019-02-27 D. Fernández-Ternero , J. M. García Calcines , E. Macías-Virgós , J. A. Vilches

We develop a general theory of extensions of flat functors along geometric morphisms of toposes, and apply it to the study of the class of theories whose classifying topos is equivalent to a presheaf topos. As a result, we obtain a…

Category Theory · Mathematics 2014-06-23 Olivia Caramello

It is well-known that for certain local connectivity assumptions the fundamental groupoid of a topological space can be equipped with a topology making it a topological groupoid. In other words, the fundamental groupoid functor can be…

Algebraic Topology · Mathematics 2018-02-02 David Michael Roberts

We use the terms $\infty$-categories and $\infty$-functors to mean the objects and morphisms in an $\infty$-cosmos: a simplicially enriched category satisfying a few axioms, reminiscent of an enriched category of fibrant objects.…

Category Theory · Mathematics 2016-06-14 Emily Riehl , Dominic Verity

We systematically investigate morphisms and equivalences of toposes from multiple points of view. We establish a dual adjunction between morphisms and comorphisms of sites, introduce the notion of weak morphism of toposes and characterize…

Category Theory · Mathematics 2020-08-04 Olivia Caramello

The main objective of this paper is to show that the homotopy colimit of a diagram of quasi-categories and indexed by a small category is a localization of Lurie's higher Grothendieck construction of the diagram. We thereby generalize…

Category Theory · Mathematics 2022-05-30 Amit Sharma

We prove a correspondence between $\kappa$-small fibrations in simplicial presheaf categories equipped with the injective or projective model structure (and left Bousfield localizations thereof) and relatively $\kappa$-compact maps in their…

Category Theory · Mathematics 2023-01-25 Raffael Stenzel

We define and study cartesian and cocartesian fibrations between categories internal to an $\infty$-topos and prove a straightening equivalence in this context.

Category Theory · Mathematics 2022-05-26 Louis Martini

We formulate a model-independent theory of co/cartesian morphisms and co/cartesian fibrations: that is, one which resides entirely *within the $\infty$-category of $\infty$-categories*. We prove this is suitably compatible with the…

Category Theory · Mathematics 2015-10-09 Aaron Mazel-Gee

Latent fibrations are an adaptation, appropriate for categories of partial maps (as presented by restriction categories), of the usual notion of fibration. The paper initiates the development of the basic theory of latent fibrations and…

Category Theory · Mathematics 2020-10-30 Robin Cockett , Geoff Cruttwell , Jonathan Gallagher , Dorette Pronk

We consider the maximal number of arbitrary points in a special fibre that can be simultaneously approached by points in one sequence of general fibres. Several results about this topological invariant and their applications describe the…

alg-geom · Mathematics 2008-02-03 Michal Kwiecinski , Piotr Tworzewski

Suppose an extension map $U\colon \mathbb{T}_1 \to \mathbb{T}_0$ in the 2-category $\mathfrak{Con}$ of contexts for arithmetic universes satisfies a Chevalley criterion for being an (op)fibration in $\mathfrak{Con}$. If $M$ is a model of…

Category Theory · Mathematics 2018-08-28 Sina Hazratpour , Steven Vickers

We study composed map germs with respect to their local fibrations. Under most general conditions, inspired by the tameness condition that was introduced recently, we prove the existence of singular tube fibrations, and we determine the…

Algebraic Geometry · Mathematics 2024-01-25 Ying Chen , Cezar Joiţa , Mihai Tibăr

In the setting of relative topos theory, we show that the pullback of a relative presheaf topos on an arbitrary fibration is the relative presheaf topos on its inverse image. To this end, we develop and exploit a notion of extension with…

Category Theory · Mathematics 2025-09-10 Léo Bartoli , Olivia Caramello

The lifting problem for continuous bi-equivariant maps and bi-equivariant covering homotopies is considered, which leads to the notion of a bi-equivariant fibration. An intrinsic characteristic of a bi-equivariant Hurewicz fibration is…

General Topology · Mathematics 2023-07-24 Pavel S. Gevorgyan

Discrete homotopy theory or A-homotopy theory is a combinatorial homotopy theory defined on graphs, simplicial complexes, and metric spaces, reflecting information about their connectivity. The present paper aims to further understand the…

Combinatorics · Mathematics 2025-03-19 So Yamagata

A fibration of graphs is an homomorphism that is a local isomorphism of in-neighbourhoods, much in the same way a covering projection is a local isomorphism of neighbourhoods. Recently, it has been shown that graph fibrations are useful…

Quantitative Methods · Quantitative Biology 2022-11-23 Paolo Boldi , Ian Leifer , Hernán A. Makse

We develop an approach to Goodwillie's calculus of functors using the techniques of higher topos theory. Central to our method is the introduction of the notion of fiberwise orthogonality, a strengthening of ordinary orthogonality which…

Algebraic Topology · Mathematics 2019-02-26 Mathieu Anel , Georg Biedermann , Eric Finster , André Joyal

In this paper, we establish a new criterion for covering maps between real algebraic varieties. Specifically, we prove that a quasi-finite, flat morphism with locally constant geometric fibers between varieties over a real closed field…

Algebraic Geometry · Mathematics 2026-03-10 Rizeng Chen