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Related papers: The condensed homotopy type of a scheme

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In this paper we define the pro-\'etale homotopy type of a scheme and prove some of its expected properties. Our definition is similar to the definition of the \'etale homotopy type by Michael Artin and Barry Mazur. We prove that for a qcqs…

Algebraic Geometry · Mathematics 2025-03-25 Paul Meffle

The pro-\'etale fundamental group of a scheme, introduced by Bhatt and Scholze, generalizes the usual \'etale fundamental group $\pi_1^{\mathrm{et}}$ defined in SGA1 and leads to an interesting class of "geometric coverings" of schemes,…

Algebraic Geometry · Mathematics 2019-11-06 Marcin Lara

We extend the study of the condensed Galois category of a scheme introduced by Barwick, Glasman and Haine in their work on Exodromy. We elaborate its connection to Lurie's work on Ultracategories and provide a description in terms of…

Algebraic Geometry · Mathematics 2026-05-12 Catrin Mair

The pro-\'etale fundamental group of a scheme, introduced by Bhatt and Scholze, generalizes formerly known fundamental groups -- the usual \'etale fundamental group $\pi_1^{\mathrm{et}}$ defined in SGA1 and the more general group defined in…

Algebraic Geometry · Mathematics 2024-02-28 Marcin Lara

Let $k$ be a field with separable closure $\bar{k}\supset k$, and let $X$ be a qcqs $k$-scheme. We use the theory of profinite Galois categories developed by Barwick-Glasman-Haine to provide a quick conceptual proof that the sequences…

Algebraic Topology · Mathematics 2022-12-22 Peter J. Haine , Tim Holzschuh , Sebastian Wolf

Faltings' approach in $p$-adic Hodge theory can be schematically divided into two main steps: firstly, a local reduction of the computation of the $p$-adic \'etale cohomology of a smooth variety over a $p$-adic local field to a Galois…

Algebraic Geometry · Mathematics 2022-01-20 Tongmu He

In this note we show that the protruncated shape of a spectral $\infty$-topos is a delocalization of its profinite stratified shape. This gives a way to reconstruct the extended \'etale homotopy groups (i.e., the non-profinitely complete…

Algebraic Geometry · Mathematics 2019-01-23 Peter J. Haine

Building on To\"en's work on affine stacks, we develop a certain homotopy theory for schemes, which we call "unipotent homotopy theory." Over a field of characteristic $p>0$, we prove that the unipotent homotopy group schemes…

Algebraic Geometry · Mathematics 2025-08-20 Shubhodip Mondal , Emanuel Reinecke

Condensed mathematics as developed by Clausen and Scholze yields a version of derived functors over the category of continuous $G$-modules for a Hausdorff topological group $G$. We study the resulting notion of group cohomology and its…

Algebraic Topology · Mathematics 2025-12-04 Emma Brink

Among all affine, flat, finitely presented group schemes, we focus on those that are pure, this includes all groups which are extensions of a finite locally free group by a group with connected fibres. We prove that over an arbitrary base…

Algebraic Geometry · Mathematics 2018-08-08 Giulia Battiston , Matthieu Romagny

We prove in this paper that for a quasi-compact and semi-separated (non necessarily noetherian) scheme X, the derived category of quasi-coherent sheaves over X, D(A_qc(X)), is a stable homotopy category in the sense of Hovey, Palmieri and…

Algebraic Geometry · Mathematics 2017-04-27 Leovigildo Alonso , Ana Jeremias , Marta Perez , Maria J. Vale

We establish a unified group-theoretic framework bridging the arithmetic homotopy exact sequence of a variety and the Birman exact sequence of a surface. Within this framework, we reinterpret classical arithmetic notions - such as the…

Algebraic Geometry · Mathematics 2025-12-24 Miltiadis Karakikes , Sotiris Karanikolopoulos , Aristides Kontogeorgis , Dimitrios Noulas

This is an expended and revised version of the preprint "Schematization of homotopy types". The purpose of this work is to introduce a notion of \emph{affine stacks}, which is a homotopy version of the notion of affine schemes, and to give…

Algebraic Geometry · Mathematics 2007-05-23 B. Toen

In this paper we will define a qc fundamental group for an arithmetic scheme by quasi-galois closed covers. Then we will give a computation for such a group and will prove that the etale fundamental group of an arithmetic scheme is a normal…

Algebraic Geometry · Mathematics 2009-12-21 Feng-Wen An

In this work we use Hodge theoretic methods to study homotopy types of complex projective manifolds with arbitrary fundamental groups. The main tool we use is the \textit{schematization functor} $X \mapsto (X\otimes \mathbb{C})^{sch}$,…

Algebraic Geometry · Mathematics 2014-01-14 L. Katzarkov , T. Pantev , B. Toen

A new approach to \'etale homotopy theory is presented which applies to a much broader class of objects than previously existing approaches, namely it applies not only to all schemes (without any local Noetherian hypothesis), but also to…

Algebraic Geometry · Mathematics 2016-07-27 David Carchedi

The theory of condensed mathematics by Dustin Clausen and Peter Scholze claims that topological spaces should be replaced by the definition of condensed sets. The main purpose of this paper is to investigate in which way the theory of…

Algebraic Topology · Mathematics 2021-05-18 Catrin Mair

This paper is a summary of author's results on finite flat commutative group schemes. The properties of the generic fibre functor are discussed. A complete classification of finite local flat commutative group schemes over mixed…

Number Theory · Mathematics 2014-06-17 M. V. Bondarko

We study the homotopy category of unbounded complexes with bounded homologies and its quotient category by the homotopy category of bounded complexes. We show the existence of a recollement of the above quotient category and it has the…

Rings and Algebras · Mathematics 2010-01-06 Osamu Iyama , Kiriko Kato , Jun-ichi Miyachi

The proalgebraic fundamental group of a connected topological space $X$, recently introduced by the first author, is an affine group scheme whose representations classify local systems of finite-dimensional vector spaces on $X$. In this…

Algebraic Geometry · Mathematics 2023-06-07 Christopher Deninger , Michael Wibmer
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