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We show that generic automorphisms of stable groups are supertight in a strong sense. In particular, we obtain the existence of supertight automorphisms. We also answer a question concerning the relationship between supertight automorphisms…

Group Theory · Mathematics 2026-04-23 Piotr Kowalski , Pınar Uğurlu Kowalski

We show that the automorphism groups of certain countable structures obtained using the Hrushovski amalgamation method are simple groups. The structures we consider are the 'uncollapsed' structures of infinite Morley rank obtained by the ab…

Logic · Mathematics 2015-09-03 David M. Evans , Zaniar Ghadernezhad , Katrin Tent

We study valued fields equipped with an automorphism. We prove that all of them have an extension admitting an equivariant cross-section of the valuation. In residual characteristic zero, and in the presence of such a cross-section, we show…

Logic · Mathematics 2025-12-18 Jan Dobrowolski , Francesco Gallinaro , Rosario Mennuni

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 show that if a group automorphism of a Cremona group of arbitrary rank is also a homeomorphism with respect to either the Zariski or the Euclidean topology, then it is inner up to a field automorphism of the base-field. Moreover, we show…

Algebraic Geometry · Mathematics 2019-09-25 Christian Urech , Susanna Zimmermann

Let $T$ be a complete theory of fields, possibly with extra structure. Suppose that model-theoretic algebraic closure agrees with field-theoretic algebraic closure, or more generally that model-theoretic algebraic closure has the exchange…

Logic · Mathematics 2023-06-28 Will Johnson , Jinhe Ye

The class of generic structures among those consisting of the measure algebra of a probability space equipped with an automorphism is axiomatizable by positive sentences interpreted using an approximate semantics. The separable generic…

Logic · Mathematics 2007-05-23 Alexander Berenstein , C. Ward Henson

We investigate some properties of regularity of homomorphisms of local algebras over positive characteristic fields. We state a result of monomialization of such a homomorphism between algebras of analytic or algebraic power series. From…

Commutative Algebra · Mathematics 2013-01-08 Guillaume Rond

We address the question of finding algebraic properties that are respectively equivalent, for a morphism between algebraic varieties over an algebraically closed field of characteristic zero, to be an homeomorphism for the Zariski topology…

Algebraic Geometry · Mathematics 2022-11-16 François Bernard , Goulwen Fichou , Jean-Philippe Monnier , Ronan Quarez

In this paper, local monomialization theorems are proven for analytic morphisms of complex and real analytic spaces. This gives the generalization of the local monomialization theorem for morphisms of algebraic varieties over a field of…

Algebraic Geometry · Mathematics 2016-12-05 Steven Dale Cutkosky

We lay the groundwork in this first installment of a series of papers aimed at developing a theory of Hrushovski-Kazhdan style motivic integration for certain type of non-archimedean o-minimal fields, namely power-bounded T-convex valued…

Logic · Mathematics 2017-06-27 Yimu Yin

Let $K$ be a field of characteristic $0$ and let $G$ and $H$ be connected commutative algebraic groups over $K$. Let $\text{Mor}_0(G,H)$ denote the set of morphisms of algebraic varieties $G \to H$ that map the neutral element to the…

Algebraic Geometry · Mathematics 2022-05-26 Gabriel Andreas Dill

We address several specific aspects of the following general question: can a field K have so many automorphisms that the action of the automorphism group on the elements of K has relatively few orbits? We prove that any field which has only…

Commutative Algebra · Mathematics 2007-05-23 Kiran S. Kedlaya , Bjorn Poonen

We study the automorphism group of the algebraic closure of a substructure A of a pseudo-finite field F. We show that the behavior of this group, even when A is large, depends essentially on the roots of unity in F. For almost all…

Logic · Mathematics 2012-01-16 Özlem Beyarslan , Ehud Hrushovski

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 classify the groups definable in the coloured fields obtained by Hrushovski amalgamation. A group definable in the bad green field is isogenous to the quotient of a subgroup of an algebraic group by a Cartesian power of the group of…

Logic · Mathematics 2015-01-20 Thomas Blossier , Amador Martin-Pizarro , Frank Olaf Wagner

In this paper, we construct explicitely polynomial automorphisms of affine n-space for certain n. More precisely, we construct algebraic subgroups of the general polynomial group GA_n(k) where k is an arbitrary base ring of characteristic…

Algebraic Geometry · Mathematics 2016-10-26 Stefan Günther

We classify the algebraic combinatorial geometries of arbitrary field extensions of transcendence degree greater than 4 and describe their groups of automorphisms. Our results and proofs extend similar results and proofs by Evans and…

Logic · Mathematics 2009-03-10 Jakub Gismatullin

Let $A$ be a finite non-abelian simple Mal'cev algebra, such as for example a finite simple non-abelian group or a finite simple non-zero ring. We show that the automorphism group of a filtered Boolean power of $A$ by the countable atomless…

Rings and Algebras · Mathematics 2025-09-25 Peter Mayr , Nik Ruškuc

A geometric first-order axiomatization of differentially closed fields of characteristic zero with several commuting derivations, in the spirit of Pierce-Pillay, is formulated in terms of a relative notion of prolongation for Kolchin-closed…

Logic · Mathematics 2011-03-04 Omar Leon Sanchez
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