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The aim of this paper is to describe all definable subgroups of SL2(K), for K a p-adically closed field. We begin by giving some "frame subgroups" which contain all nilpotent or solvable subgroups of SL2(K). A complete description is givien…

Logic · Mathematics 2015-01-28 Benjamin Druart

We study definable sets, groups, and fields in the theory $T_\infty$ of infinite-dimensional vector spaces over an algebraically closed field equipped with a nondegenerate symmetric (or alternating) bilinear form. First, we define an…

Logic · Mathematics 2023-11-14 Jan Dobrowolski

We consider d-minimal expansions of ordered fields. We demonstrate the existence of definable quotients of definable sets by definable equivalence relations when several technical conditions are satisfied. These conditions are satisfied…

Logic · Mathematics 2023-11-16 Masato Fujita

Many common finite p-groups admit automorphisms of order coprime to p, and when p is odd, it is reasonably difficult to find finite p-groups whose automorphism group is a p-group. Yet the goal of this paper is to prove that the automorphism…

Group Theory · Mathematics 2013-05-09 Geir T. Helleloid , Ursula Martin

We prove that in an arbitrary o-minimal structure, every interpretable group is definably isomorphic to a definable one. We also prove that every definable group lives in a cartesian product of one-dimensional definable group-intervals (or…

Logic · Mathematics 2011-11-01 Janak Ramakrishnan , Ya'acov Peterzil , Pantelis Eleftheriou

We give a complete list of the one-dimensional groups definable in algebraically closed valued fields and i the pseudo-local fields, up to a finite index subgroup and a quotient by a finite subgroup.

Logic · Mathematics 2025-03-04 Juan Pablo Acosta , Martin Hils

For a prime $p$, fusion systems over discrete $p$-toral groups are categories that model and generalize the $p$-local structure of Lie groups and certain other infinite groups in the same way that fusion systems over finite $p$-groups model…

Group Theory · Mathematics 2025-05-07 Carles Broto , Ran Levi , Bob Oliver

We study groups and rings definable in d-minimal expansions of ordered fields. We generalize to such objects some known results from o-minimality. In particular, we prove that we can endow a definable group with a definable topology making…

Logic · Mathematics 2021-07-12 Antongiulio Fornasiero

We prove several structural results on definably compact groups G in o-minimal expansions of real closed fields, such as (i) G is definably an almost direct product of a semisimple group and a commutative group, and (ii) the group (G, .) is…

Logic · Mathematics 2008-11-04 Ehud Hrushovski , Ya'acov Peterzil , Anand Pillay

We introduce a class of theories called metastable, including the theory of algebraically closed valued fields (ACVF) as a motivating example. The key local notion is that of definable types dominated by their stable part. A theory is…

Logic · Mathematics 2024-07-03 Ehud Hrushovski , Silvain Rideau-Kikuchi

We define general notions of coordinate geometries over fields and ordered fields, and consider coordinate geometries that are given by finitely many relations that are definable over those fields. We show that the automorphism group of…

Logic · Mathematics 2025-07-15 Judit Madarász , Mike Stannett , Gergely Székely

This paper targets to generalize the notion of Hopfian groups in the commutative case by defining the so-called {\bf relatively Hopfian groups} and {\bf weakly Hopfian groups}, and establishing some their crucial properties and…

Group Theory · Mathematics 2024-08-09 Andrey R. Chekhlov , Peter V. Danchev , Brendan Goldsmith , Patrick W. Keef

The motivation for this paper is to extend the known model theoretic treatment of differential Galois theory to the case of linear difference equations (where the derivative is replaced by an automorphism.) The model theoretic difficulties…

Logic · Mathematics 2009-03-15 Moshe Kamensky

We study the definable topological dynamics $(G,S_G(M))$ of a definable group acting on its type space, where $M$ is a structure and $G$ is a group definable in $M$. In \cite{Newelski-I}, Newelski raised a question of whether weakly generic…

Logic · Mathematics 2023-02-22 Ningyuan Yao , Zhentao Zhang

In this paper, we study definably compact semigroups in o-minimal structures, aiming to extend the theory of definable groups to a broader algebraic setting. We show that any definably compact semigroup contains idempotents and admits a…

Logic · Mathematics 2025-07-28 Eduardo Magalhães

We consider an arbitrary topological group $G$ definable in a structure $\mathcal M$, such that some basis for the topology of $G$ consists of sets definable in $\mathcal M$. To each such group $G$ we associate a compact $G$-space of…

Logic · Mathematics 2015-06-15 Ya'Acov Peterzil , Sergei Starchenko

This paper has two parts. In the first one, we prove that an invariant dp-minimal type is either finitely satisfiable or definable. We also prove that a definable version of the (p,q)-theorem holds in dp-minimal theories of small or medium…

Logic · Mathematics 2015-09-24 Pierre Simon

Let $\mathcal G$ denote the space of finitely generated marked groups. For any finitely generated group $G$, we construct a continuous, injective map $f$ from the space of subgroups $Sub(G)$ to $\mathcal G$ that sends conjugate subgroups to…

Group Theory · Mathematics 2024-03-27 D. Osin

We show that an infinite group $G$ definable in a $1$-h-minimal field admits a strictly $K$-differentiable structure with respect to which $G$ is a (weak) Lie group, and show that definable local subgroups sharing the same Lie algebra have…

Logic · Mathematics 2023-03-03 Juan Pablo Acosta , Assaf Hasson

We study definably complete locally o-minimal expansions of ordered groups in this paper. A definable continuous function defined on a closed, bounded and definable set behave like a continuous function on a compact set. We demonstrate…

Logic · Mathematics 2023-06-09 Masato Fujita