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Related papers: Colimits in the $\infty$-category of $\infty$-topo…

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We characterise proper morphisms of $\infty$-topoi in terms of a relativised notion of compactness: we show that a geometric morphism of $\infty$-topoi is proper if and only if it commutes with colimits indexed by filtered internal…

Category Theory · Mathematics 2025-03-18 Louis Martini , Sebastian Wolf

We prove that every categorical model of dependent type theory with dependent sums and products, intensional identity types and univalent universes presents via its $\infty$-localisation an elementary $\infty$-topos, that is, a finitely…

Category Theory · Mathematics 2026-04-30 Maximilian Petrowitsch

Inspired by Lurie's theory of quasi-unital algebras we prove an analogous result for $\infty$-categories. In particular, we show that the unital structure of an $\infty$-category can be uniquely recovered from the underlying non-unital…

Algebraic Topology · Mathematics 2016-01-20 Yonatan Harpaz

Riehl and Verity have established that for a quasi-category $A$ that admits limits, and a homotopy coherent monad on $A$ which does not preserve limits, the Eilenberg-Moore object still admits limits; this can be interpreted as a…

Category Theory · Mathematics 2025-05-22 Joanna Ko

We define an elementary $\infty$-topos that simultaneously generalizes an elementary topos and Grothendieck $\infty$-topos. We then prove it satisfies the expected topos theoretic properties, such as descent, local Cartesian closure,…

Category Theory · Mathematics 2022-01-11 Nima Rasekh

In this paper we prove an $\infty$-categorical version of the reflection theorem of Ad\'amek-Rosick\'y. Namely, that a full subcategory of a presentable $\infty$-category which is closed under limits and $\kappa$-filtered colimits is a…

Algebraic Topology · Mathematics 2022-07-20 Shaul Ragimov , Tomer M. Schlank

We develop the theory of topoi internal to an arbitrary $\infty$-topos $\mathcal B$. We provide several characterisations of these, including an internal analogue of Lurie's characterisation of $\infty$-topoi, but also a description in…

Category Theory · Mathematics 2025-03-19 Louis Martini , Sebastian Wolf

We prove that an \'etale fibration between $L_\infty$-bundles admits local sections composed of several elementary morphisms of particularly simple and accessible type. As applications, we establish an inverse function theorem for…

Differential Geometry · Mathematics 2026-03-02 Kai Behrend , Hsuan-Yi Liao , Ping Xu

In this note we prove the following useful fact that seems to be missing from the literature: the $\infty$-category of coherent ordinary topoi (in the sense of SGA4) is equivalent to the $\infty$-category of coherent $1$-localic…

Algebraic Geometry · Mathematics 2019-07-12 Peter J. Haine

We show that there are infinitely many distinct closed classes of colimits (in the sense of the Galois connection induced by commutation of limits and colimits in Set) which are intermediate between the class of pseudo-filtered colimits and…

Category Theory · Mathematics 2015-05-06 Marie Bjerrum , Peter Johnstone , Tom Leinster , William F. Sawin

A generalization of the notion of an $\infty$-category is presented, allowing for ($\infty$-)cat(egorie)s that may have non-invertible higher morphisms.

Category Theory · Mathematics 2014-03-10 Daniel Gerigk

After developing the basic theory of locally cartesian localizations of presentable locally cartesian closed infinity-categories, we establish the representability of equivalences and show that univalent families, in the sense of Voevodsky,…

Category Theory · Mathematics 2017-05-30 David Gepner , Joachim Kock

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 establish new general etale versions of theorems of Barth and Sommese. Respectively, we compute the lower etale cohomology of closed subvarieties of $P^N$ of small codimensions and of their preimages with respect to proper morphisms…

Algebraic Geometry · Mathematics 2025-07-10 Sergei I. Arkhipov , Mikhail V. Bondarko

We take a novel lattice-theoretic approach to the $\tau$-cluster morphism category $\mathfrak{T}(A)$ of a finite-dimensional algebra $A$ and define the category via the lattice of torsion classes $\mathrm{tors } A$. Using the lattice…

Representation Theory · Mathematics 2025-02-26 Maximilian Kaipel

If the Continuum Hypothesis is false, it implies the existence of cardinalities between the integers and the real numbers. In studying these "cardinal characteristics of the continuum", it was discovered that many of the associated…

Logic · Mathematics 2025-04-11 David Philips

In this article we extend Deligne's construction of Grothendieck's six operations on the derived category of torsion sheaves over the \'etale site of a scheme for morphisms of finite type to a larger class of morphisms. This class includes…

Algebraic Geometry · Mathematics 2019-02-14 Paul Hamacher

In a previous article, we introduced notions of finiteness obstruction, Euler characteristic, and L^2-Euler characteristic for wide classes of categories. In this sequel, we prove the compatibility of those notions with homotopy colimits of…

Algebraic Topology · Mathematics 2011-03-28 Thomas M. Fiore , Wolfgang Lück , Roman Sauer

We show that the quasicategory defined as the localization of the category of (simple) graphs at the class of A-homotopy equivalences does not admit colimits. In particular, we settle in the negative the question of whether the A-homotopy…

Combinatorics · Mathematics 2023-09-06 Daniel Carranza , Chris Kapulkin , Jinho Kim

We develop a theory of higher order structures in compact abelian groups. In the frame of this theory we prove general inverse theorems and regularity lemmas for Gowers's uniformity norms. We put forward an algebraic interpretation of the…

Combinatorics · Mathematics 2012-03-13 Balazs Szegedy
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