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Let $k$ be an infinite finitely generated field of characteristic $p>0$. Fix a separated scheme $X$ smooth, geometrically connected, and of finite type over $k$ and a smooth proper morphism $f:Y\rightarrow X$. The main result of this paper…

Algebraic Geometry · Mathematics 2025-10-31 Emiliano Ambrosi

If the $\ell$-adic cohomology of a projective smooth variety, defined over a local field $K$ with finite residue field $k$, is supported in codimension $\ge 1$, then every model over the ring of integers of $K$ has a $k$-rational point. For…

Number Theory · Mathematics 2007-06-08 Hélène Esnault , Chenyang Xu

The purpose of this survey is to explain some recent results about analogies between characteristic 0 and characteristic $p>0$ geometry, and to discuss an infinitesimal variant of motivic cohomology. More specifically, we review results…

Algebraic Geometry · Mathematics 2013-08-26 Manuel Blickle , Hélène Esnault , Kay Rülling

We study properties of compactly supported $p$-adic pro-\'etale cohomology of smooth partially proper rigid analytic varieties. In particular, we prove a comparison theorem, in a stable range, with compactly supported syntomic cohomology,…

Algebraic Geometry · Mathematics 2025-01-24 Piotr Achinger , Sally Gilles , Wiesława Nizioł

Let ${\mathcal H}_{q}(d)$ be the Iwahori-Hecke algebra for the symmetric group, where $q$ is a primitive $l$th root of unity. In this paper we develop a theory of support varieties which detects natural homological properties such as the…

Representation Theory · Mathematics 2018-02-06 Daniel K. Nakano , Ziqing Xiang

The goal of this paper is to offer a new construction of the de Rham-Witt complex of smooth varieties over perfect fields of characteristic $p>0$. We introduce a category of cochain complexes equipped with an endomorphism $F$ of underlying…

Algebraic Geometry · Mathematics 2020-02-20 Bhargav Bhatt , Jacob Lurie , Akhil Mathew

Over any smooth algebraic variety over a $p$-adic local field $k$, we construct the de Rham comparison isomorphisms for the \'etale cohomology with partial compact support of de Rham $\mathbb Z_p$-local systems, and show that they are…

Algebraic Geometry · Mathematics 2022-11-01 Kai-Wen Lan , Ruochuan Liu , Xinwen Zhu

We construct a new Weil cohomology for smooth projective varieties over a field, universal among Weil cohomologies with values in rigid additive tensor categories. A similar universal problem for Weil cohomologies with values in rigid…

Algebraic Geometry · Mathematics 2025-02-04 L. Barbieri-Viale , B. Kahn

In this paper we present a combinatorial proof of the Kronecker--Weber Theorem for global fields of positive characteristic. The main tools are the use of Witt vectors and their arithmetic developed by H. L. Schmid. The key result is to…

Number Theory · Mathematics 2013-07-16 Julio Cesar Salas-Torres , Martha Rzedowski-Calderón , Gabriel Villa-Salvador

If $V$ is a smooth projective variety defined over a local field $K$ with finite residue field, so that its \'etale cohomology over the algebraic closure $\bar{K}$ is supported in codimension 1, then the mod $p$ reduction of a projective…

Number Theory · Mathematics 2007-05-23 Hélène Esnault

We prove that a singular complex surface that admits a complete holomorphic vector field that has no invariant curve through a singular point of the surface is obtained from a Kato surface by contracting some divisor (in particular, it is…

Dynamical Systems · Mathematics 2016-03-09 Adolfo Guillot

We show that the functor of $p$-typical co-Witt vectors on commutative algebras over a perfect field $k$ of characteristic $p$ is defined on, and in fact only depends on, a weaker structure than that of a $k$-algebra. We call this structure…

Algebraic Topology · Mathematics 2021-10-28 Tilman Bauer

For a natural class of cohomology theories with support (including \'etale or pro-\'etale cohomology with suitable coefficients), we prove a moving lemma for cohomology classes with support on smooth quasi-projective k-varieties that admit…

Algebraic Geometry · Mathematics 2026-05-27 Stefan Schreieder

We show that given a simple abelian variety $A$ and a normal variety $V$ defined over a finitely generated field $K$ of characteristic zero, the set of non-constant morphisms $V \to A$ satisfying certain tangency conditions imposed by a…

Algebraic Geometry · Mathematics 2025-02-14 Finn Bartsch

We use the theory of Condensed Mathematics to build a condensed cohomology theory for the Weil group of a $p$-adic field. The cohomology groups are proved to be locally compact abelian groups of finite ranks in some special cases. This…

Number Theory · Mathematics 2025-03-19 Marco Artusa

Let $K$ be a finite extension of $\mathbb{Q}_p$ and $X$ a smooth proper $K$-variety with good reduction. Under a mild assumption on the behaviour of Hodge numbers under reduction modulo $p$, we prove that the existence of a non-zero global…

Algebraic Geometry · Mathematics 2025-10-31 Emiliano Ambrosi , Rachel Newton , Margherita Pagano

We extend the notion of absolute subsets of Betti moduli spaces of smooth algebraic varieties to the case of normal varieties. As a consequence we prove that twisted cohomology jump loci in rank one over a normal variety are a finite union…

Algebraic Geometry · Mathematics 2022-02-15 Leonardo A. Lerer

Given an effective Cartier divisor D with simple normal crossing support on a smooth and proper scheme X over a perfect field of positive characteristic p, there is a natural notion of de Rham-Witt sheaves on X with zeros along D. We show…

Algebraic Geometry · Mathematics 2024-03-28 Fei Ren , Kay Rülling

For every commutative ring $A$, one has a functorial commutative ring $W(A)$ of $p$-typical Witt vectors of $A$, an iterated extension of $A$ by itself. If $A$ is not commutative, it has been known since the pioneering work of L. Hesselholt…

Algebraic Geometry · Mathematics 2017-10-13 D. Kaledin

We show that various flavors of Witt vectors are functorial with respect to multiplicative polynomial laws of finite degree. We then deduce that the $p$-typical Witt vectors are functorial in multiplicative polynomial maps of degree at most…

Algebraic Topology · Mathematics 2020-10-19 Emanuele Dotto , Kristian Moi , Irakli Patchkoria