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We provide axiomatization and relative quantifier elimination for valued fields equipped with an automorphism, in residue characteristic zero. Similar results are known under strong assumptions on the interaction between the automorphism…

Logic · Mathematics 2013-09-24 Gönenç Onay , Salih Durhan

We improve results of Belair, Macintyre, and Scanlon on valued fields with a valuation preserving automorphism by weakening their assumptions on the residue difference field. In the equicharacteristic zero case we also determine the induced…

Logic · Mathematics 2009-11-24 Salih Azgin , Lou van den Dries

We prove that a quasi-finite endomorphism of an algebraic variety over an algebraically closed field of characteristic zero, that is injective on the complement of a closed subvariety, is an automorphism. We also prove that an endomorphism…

Algebraic Geometry · Mathematics 2021-04-02 Nilkantha Das

We extend the characterization of extremal valued fields given in \cite{[AKP]} to the missing case of valued fields of mixed characteristic with perfect residue field. This leads to a complete characterization of the tame valued fields that…

Logic · Mathematics 2016-07-12 Sylvy Anscombe , Franz-Viktor Kuhlmann

We study valued fields equipped with an automorphism $\sigma$ which is locally infinitely contracting in the sense that $\alpha\ll\sigma\alpha$ for all $0<\alpha\in\Gamma$. We show that various notions of valuation theory, such as Henselian…

Logic · Mathematics 2025-06-10 Yuval Dor , Ehud Hrushovski

We show that on an Abelian variety over an algebraically closed field of positive characteristic, the obstruction to lifting an automorphism to an Abelian variety over a field of characteristic zero as a morphism vanishes if and only if it…

Algebraic Geometry · Mathematics 2020-01-23 Tanya Kaushal Srivastava

We prove that the category of ordered abelian groups equipped with an automorphism has the Amalgamation Property, deduce that their inductive theory is NIP in the sense of positive logic, and initiate a development of the latter framework.…

Logic · Mathematics 2025-03-14 Jan Dobrowolski , Rosario Mennuni

We study in detail the valuation theory of deeply ramified fields and introduce and investigate several other related classes of valued fields. Further, a classification of defect extensions of prime degree of valued fields that was earlier…

Commutative Algebra · Mathematics 2023-01-12 Franz-Viktor Kuhlmann , Anna Rzepka

We classify Artin-Schreier extensions of valued fields with non-trivial defect according to whether they are connected with purely inseparable extensions with non-trivial defect, or not. We use this classification to show that in positive…

Commutative Algebra · Mathematics 2013-04-02 Franz-Viktor Kuhlmann

Let G be a connected reductive algebraic group over a perfect field. We study the representability of the equivariant automorphism group of G-varieties. For a broad class of complexity-one G-varieties, we show that this group is…

Algebraic Geometry · Mathematics 2026-02-09 Giancarlo Lucchini Arteche , Ronan Terpereau

We prove that if a field k is infinite, char(k)=0 and k has not nontrivial automorphisms then automorphic equivalence of representations of Lie algebras coincide with geometric equivalence. We achieve our result by consideration of 1-sorted…

Rings and Algebras · Mathematics 2012-10-10 I. Shestakov , A. Tsurkov

We resolve the strong Elementary Equivalence versus Isomorphism Problem for finitely generated fields. That is, we show that for every field in this class there is a first-order sentence which characterizes this field within the class up to…

Logic · Mathematics 2023-11-02 Philip Dittmann , Florian Pop

In this paper, we prove that every iterative differential embedding problem over an algebraic function field in positive characteristic with an algebraically closed field of constants has a proper solution.

Commutative Algebra · Mathematics 2011-07-12 Stefan Ernst

In this paper, we prove weak elimination of imaginaries for perfect bounded pseudo-algebraically closed fields equipped with finitely many independent valuations. Our approach combines an extension result for types to invariant types with…

Logic · Mathematics 2026-04-03 Bryan González Leandro

In recent decades, the defect of finite extensions of valued fields has emerged as the main obstacle in several fundamental problems in algebraic geometry such as the local uniformization problem. Hence, it is important to identify…

Commutative Algebra · Mathematics 2025-03-24 Caio Henrique Silva de Souza , Mark Spivakovsky

Abraham Robinson's method for finding model completions is refined and and generalized for model companions and is applied to the theory of fields equipped with both a valuation and an automorphism.

Logic · Mathematics 2020-12-29 Özlem Beyarslan , Daniel Max Hoffmann , Gönenç Onay , David Pierce

We show that the generic automorphism is axiomatisable in the green field of Poizat (once Morleyised) as well as in the bad fields which are obtained by collapsing this green field to finite Morley rank. As a corollary, we obtain "bad…

Logic · Mathematics 2012-01-04 Martin Hils

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 study properties of eigenvalues of a matrix associated with a randomly chosen partial automorphism of a regular rooted tree. We show that asymptotically, as the numbers of levels goes to infinity, the fraction of non-zero eigenvalues…

Group Theory · Mathematics 2020-06-30 Eugenia Kochubinska

We characterise the existentially closed models of the theory of exponential fields. They do not form an elementary class, but can be studied using positive logic. We find the amalgamation bases and characterise the types over them. We…

Logic · Mathematics 2021-01-19 Levon Haykazyan , Jonathan Kirby
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