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Related papers: Grothendieck Galois theory and \'etale exodromy

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The exodromy correspondence of Barwick, Glasman, and Haine computes constructible sheaves of spaces on a scheme $X$ as an $\infty$-category of continuous functors from the profinite category $\operatorname{Gal}(X)$. Viewing…

Algebraic Geometry · Mathematics 2026-05-22 Remy van Dobben de Bruyn

We introduce the category of finite \'etale covers of an arbitrary schematic finite space $X$ and show that, equipped with an appropriate natural fiber functor, it is a Galois Category. This allows us to define the \'etale fundamental group…

Algebraic Geometry · Mathematics 2021-05-06 J. Sánchez González , C. Tejero Prieto

Let $X$ be a quasicompact quasiseparated scheme. Write $\operatorname{Gal}(X)$ for the category whose objects are geometric points of $X$ and whose morphisms are specializations in the \'etale topology. We define a natural profinite…

Algebraic Topology · Mathematics 2020-08-25 Clark Barwick , Saul Glasman , Peter Haine

In this short note we extend the Exodromy Theorem of arXiv:1807.03281 to a large class of stacks and higher stacks. We accomplish this by extending the Galois category construction to simplicial schemes. We also deduce that the nerve of the…

Algebraic Geometry · Mathematics 2019-01-29 Clark Barwick , Peter Haine

We show that for quasi-compact quasi-separated schemes of finite dimension, the constructibility condition in real \'etale cohomology agrees with a notion of constructibility arising naturally from topology. As application we prove that the…

Algebraic Geometry · Mathematics 2022-01-04 Fangzhou Jin

We give a new definition of the derived category of constructible $\ell$-adic sheaves on a scheme, which is as simple as the geometric intuition behind them. Moreover, we define a refined fundamental group of schemes, which is large enough…

Algebraic Geometry · Mathematics 2014-12-18 Bhargav Bhatt , Peter Scholze

We show that compact subanalytic stratified spaces and algebraic stratifications of real varieties have finite exit-path $\infty$-categories, refining classical theorems of Lefschetz-Whitehead, Lojasiewicz, and Hironaka on the finiteness of…

Algebraic Topology · Mathematics 2024-01-24 Peter J. Haine , Mauro Porta , Jean-Baptiste Teyssier

This paper gives an explicit computation of the category of constructible sheaves on a toric variety (with respect to the stratification by torus orbits). Over the complex numbers, this simplifies a description due to Braden and Lunts. The…

Algebraic Geometry · Mathematics 2024-10-10 Remy van Dobben de Bruyn

We prove that a strongly $F$-regular scheme $X$ admits a finite, generically Galois, and \'etale-in-codimension-one cover $\widetilde X \to X$ such that the \'etale fundamental groups of $\widetilde X$ and $\widetilde X_{reg}$ agree.…

Algebraic Geometry · Mathematics 2019-08-14 Bhargav Bhatt , Javier Carvajal-Rojas , Patrick Graf , Karl Schwede , Kevin Tucker

We improve the exodromy equivalence of MacPherson, Treumann and Lurie in several ways: first, we allow stratified spaces that have locally weakly contractible strata, rather than being locally of singular shape, we remove all noetherianity…

Algebraic Topology · Mathematics 2022-11-10 Mauro Porta , Jean-Baptiste Teyssier

We prove that under some extra hypothesis, given an \'etale endomorphism of a normal irreducible Noetherian and simply connected scheme, if the endomorphism is surjective then it is injective. The additional assumption concerns the…

Algebraic Geometry · Mathematics 2024-09-24 Lázaro O. Rodríguez Díaz

Let $X$ be a complete smooth variety defined over number field $K$ and $i$ an integer. The absolute Galois group of $K$ acts on the $i$th $l$-adic etale cohomology of $X$ for all $l$, producing a system of $l$-adic representations…

Number Theory · Mathematics 2017-02-24 Chun Yin Hui

Generalized \'etale homotopy pro-groups $\pi_1^{\ets}(\mc{C}, x)$ associated to pointed connected small Grothendieck sites $(\mc{C}, x)$ are defined and their relationship to Galois theory and the theory of pointed torsors for discrete…

Algebraic Topology · Mathematics 2010-02-19 Michael D. Misamore

We relate two different proposals to extend the \'etale topology into homotopy theory, namely via the notion of finite cover introduced by Mathew and via the notion of separable commutative algebra introduced by Balmer. We show that finite…

Algebraic Topology · Mathematics 2025-05-29 Niko Naumann , Luca Pol

An \'etale structure over a topological space $X$ is a continuous family of structures (in some first-order language) indexed over $X$. We give an exposition of this fundamental concept from sheaf theory and its relevance to countable model…

Logic · Mathematics 2023-10-19 Ruiyuan Chen

We generalize the notion of a small sheaf of sets over a topological space or manifold to define the notion of a small stack of groupoids over an \'etale topological or differentiable stack. We then provide a construction analogous to the…

Algebraic Topology · Mathematics 2012-03-28 David Carchedi

Building on Beilinson's work, ``constructible sheaves are holonomic,'' we introduce the notion of holonomicity for \'etale sheaves, without assuming a priori constructibility. Over a perfect base field, we establish the converse of…

Algebraic Geometry · Mathematics 2024-10-08 Ahmed Abbes , Takeshi Saito

We define a theory of etale motives over a noetherian scheme. This provides a system of categories of complexes of motivic sheaves with integral coefficients which is closed under the six operations of Grothendieck. The rational part of…

Algebraic Geometry · Mathematics 2019-02-20 Denis-Charles Cisinski , Frédéric Déglise

We present a uniform theory of constructible sheaves on arbitrary schemes with coefficients in topological or even condensed rings. This is accomplished by defining lisse sheaves to be the dualizable objects in the derived infinity-category…

Algebraic Geometry · Mathematics 2023-05-30 Tamir Hemo , Timo Richarz , Jakob Scholbach

The purpose of this paper is to constructively develop a Galois theory on irreducible shifts of finite type (SFTs) and to analyze the automorphism groups of SFTs using this framework. Let $X$ and $Y$ be irreducible SFTs. We demonstrate that…

Dynamical Systems · Mathematics 2026-05-28 Kazutoyo Iketake
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