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Related papers: A density property of Henselian valued fields

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In this paper we suggest new effective criteria for the density property. This enables us to give a trivial proof of the original Anders\'en-Lempert result and to establish (almost free of charge) the algebraic density property for all…

Complex Variables · Mathematics 2009-11-13 Shulim Kaliman , Frank Kutzschebauch

We show that every henselian valued field $L$ of residue characteristic 0 admits a proper subfield $K$ which is dense in $L$. We present conditions under which this can be taken such that $L|K$ is transcendental and $K$ is henselian. These…

Commutative Algebra · Mathematics 2010-03-31 Franz-Viktor Kuhlmann

We develop geometry of algebraic subvarieties of $K^{n}$ over arbitrary Henselian valued fields $K$. This is a continuation of our previous article concerned with algebraic geometry over rank one valued fields. At the center of our approach…

Algebraic Geometry · Mathematics 2020-03-10 Krzysztof Jan Nowak

We introduce the manifold density function, which is an intrinsic method to validate manifold learning techniques. Our approach adapts and extends Ripley's $K$-function, and categorizes in an unsupervised setting the extent to which an…

Machine Learning · Computer Science 2024-02-16 Benjamin Holmgren , Eli Quist , Jordan Schupbach , Brittany Terese Fasy , Bastian Rieck

Let $K$ be a number field with ring of integers $\mathcal O$. After introducing a suitable notion of density for subsets of $\mathcal O$, generalizing that of natural density for subsets of $\mathbb Z$, we show that the density of the set…

Number Theory · Mathematics 2019-02-13 Andrea Ferraguti , Giacomo Micheli

The main purpose of the paper is to establish a closedness theorem over Henselian valued fields $K$ of equicharacteristic zero (not necessarily algebraically closed) with separated analytic structure. It says that every projection with a…

Algebraic Geometry · Mathematics 2018-01-09 Krzysztof Jan Nowak

We prove the existence of definable retractions onto arbitrary closed subsets of $K^{n}$ definable over Henselian valued fields $K$. Hence directly follows non-Archimedian analogues of the Tietze--Urysohn and Dugundji theorems on extending…

Algebraic Geometry · Mathematics 2019-04-02 Krzysztof Jan Nowak

Let $K$ be a Henselian, non-trivially valued field with separated analytic structure. We prove the existence of definable retractions onto an arbitrary closed definable subset of $K^{n}$. Hence directly follow definable non-Archimedean…

Algebraic Geometry · Mathematics 2019-02-01 Krzysztof Jan Nowak

We introduce the notion of the algebraic overshear density property which implies both the algebraic notion of flexibility and the holomorphic notion of the density property. We investigate basic consequences of this stronger property, and…

Complex Variables · Mathematics 2023-10-31 Rafael B. Andrist , Frank Kutzschebauch

This paper develops algebraic geometry over Henselian real valued (i.e. of rank 1) fields $K$, being a sequel to our paper about that over Henselian discretely valued fields. Several results are given including: a certain concept of fiber…

Algebraic Geometry · Mathematics 2016-08-30 Krzysztof Jan Nowak

We study existential theories of henselian valued fields of positive characteristic with parameters from a trivially valued subfield. Compared to previous work, we relax perfectness and separability assumptions, and instead work with the…

Logic · Mathematics 2026-02-25 Philip Dittmann

We are concerned with topology of Hensel minimal structures on non-trivially valued fields $K$, whose axiomatic theory was introduced in a recent paper by Cluckers-Halupczok-Rideau. We additionally require that every definable subset in the…

Algebraic Geometry · Mathematics 2024-12-10 Krzysztof Jan Nowak

We present a unifying theory of fields with certain classes of analytic functions, called fields with analytic structure. Both real closed fields and Henselian valued fields are considered. For real closed fields with analytic structure,…

Logic · Mathematics 2009-08-18 Raf Cluckers , Leonard Lipshitz

We prove in arbitrary characteristic that an immediate valued algebraic function field $F$ of transcendence degree 1 over a tame field $K$ is contained in the henselization of $K(x)$ for a suitably chosen $x\in F$. This eliminates…

Commutative Algebra · Mathematics 2019-01-28 Franz-Viktor Kuhlmann

This paper provides, over Henselian valued fields, some theorems on implicit function and of Artin--Mazur on algebraic power series. Also discussed are certain versions of the theorems of Abhyankar--Jung and Newton--Puiseux. The latter is…

Algebraic Geometry · Mathematics 2017-03-27 Krzysztof Jan Nowak

This paper is concerned with algebraic geometry over complete discretely valued fields $K$ of equicharacteristic zero. Several results are given including: the canonical projection $K^{n} \times K\mathbb{P}^{m} \longrightarrow K^{n}$ and…

Algebraic Geometry · Mathematics 2016-08-30 Krzysztof Jan Nowak

Let $K$ be a countable field. Then $K$ is large in the sense of Pop if and only if it admits a field topology which is "generalized t-henselian" (gt-henselian) in the sense of Dittmann, Walsberg, and Ye, meaning that the implicit function…

Logic · Mathematics 2025-08-22 Will Johnson

In this survey of the Andersen-Lempert theory we present the state of the art in the study of the density property (which means that the Lie algebra generated by completely integrable holomorphic vector fields on a given Stein manifold is…

Complex Variables · Mathematics 2010-03-18 Shulim Kaliman , Frank Kutzschebauch

We use weighted polynomial approximation to prove the existence of a compact set K with non-empty interior and a function f is dense in the space A(K) of all continuous functions on K that are holomorphic in the interior of K, endowed with…

Complex Variables · Mathematics 2025-06-26 Stéphane Charpentier , Konstantinos Maronikolakis

We study when the property that a field is dense in its real and p-adic closures is elementary in the language of rings and deduce that all models of the theory of algebraic fields have this property.

Logic · Mathematics 2023-03-08 Sylvy Anscombe , Philip Dittmann , Arno Fehm
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