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Let N be an o-minimal expansion of a real closed field. We develop cohomology theory for the category of N-definable manifolds and N-definable maps, and use this to solve the Peterzil-Steinhorn problem on the existence of torsion points on…

Logic · Mathematics 2007-05-23 Mario J. Edmundo

The group configuration in o-minimal structures gives rise, just like in the stable case, to a transitive action of a type-definable group on a partial type. Because $acl=dcl$ the o-minimal proof is significantly simpler than Hrushovski's…

Logic · Mathematics 2020-06-01 Ya'acov Peterzil

We show that every definable group G in an o-minimal structure is definably finitely generated. That is, G contains a finite subset that is not included in any proper definable subgroup. This provides another proof, and a generalization to…

Logic · Mathematics 2023-07-25 Annalisa Conversano

It is known that a definably compact group G is an extension of a compact Lie group L by a divisible torsion-free normal subgroup. We show that the o-minimal higher homotopy groups of G are isomorphic to the corresponding higher homotopy…

Logic · Mathematics 2009-11-27 Alessandro Berarducci , Marcello Mamino , Margarita Otero

In this paper we study the relation between the category of real Lie groups and that of groups definable in o-minimal expansions of the real field, which we will refer to as ``definable groups''. With this terminology, it is known…

Logic · Mathematics 2025-02-27 Alf Onshuus

We prove Zilber's Trichotomy Conjecture for strongly minimal expansions of two-dimensional groups, definable in o-minimal structures: Theorem. Let M be an o-minimal expansion of a real closed field, (G;+) a 2-dimensional group definable in…

Logic · Mathematics 2021-04-13 Pantelis Eleftheriou , Assaf Hasson , Ya'acov Peterzil

We study directed sets definable in o-minimal structures, showing that in expansions of ordered fields these admit cofinal definable curves, as well as a suitable analogue in expansions of ordered groups, and furthermore that no analogue…

Logic · Mathematics 2021-09-17 Pablo Andujar Guerrero , Margaret E. M. Thomas , Erik Walsberg

We establish the first global results for groups definable in tame expansions of o-minimal structures. Let $\mathcal N$ be an expansion of an o-minimal structure $\mathcal M$ that admits a good dimension theory. The setting includes dense…

Logic · Mathematics 2018-07-20 Pantelis E. Eleftheriou

In this note we show that every definably connected, definably compact abelian definable group in an o-minimal expansion of a real closed field of dimension not 4 is definably homeomorphic to a torus of the same dimension. Moreover, in the…

Logic · Mathematics 2014-02-26 Elias Baro , Alessandro Berarducci

We propose new structures called almost o-minimal structures and $\mathfrak X$-structures. The former is a first-order expansion of a dense linear order without endpoints such that the intersection of a definable set with a bounded open…

Logic · Mathematics 2022-06-08 Masato Fujita

Let $\mathcal M$ be a weakly o-minimal non-valuational structure, and $\mathcal N$ its canonical o-minimal extension (by Wencel). We prove that every group $G$ definable in $\mathcal M$ is a subgroup of a group $K$ definable in $\mathcal…

Logic · Mathematics 2020-03-03 Pantelis E. Eleftheriou

We give a presentation of various results on zero-groups in o-minimal structures together with some new observations. In particular we prove that if G is a definably connected definably compact group in an o-minimal expansion of a real…

Logic · Mathematics 2007-05-23 Alessandro Berarducci

We consider definably complete and Baire expansions of ordered fields: every definable subset of the domain of the structure has a supremum and the domain can not be written as the union of a definable increasing family of nowhere dense…

Logic · Mathematics 2010-05-18 Antongiulio Fornasiero , Tamara Servi

We study definably compact definably connected groups definable in a sufficiently saturated real closed field $R$. We introduce the notion of group-generic point for $\bigvee$-definable groups and show the existence of group-generic points…

Logic · Mathematics 2017-05-19 Eliana Barriga

We prove generic differentiability in $P$-minimal theories, strengthening an earlier result of Kuijpers and Leenknegt. Using this, we prove Onshuus and Pillay's $P$-minimal analogue of Pillay's conjectures on o-minimal groups. Specifically,…

Logic · Mathematics 2026-03-16 Will Johnson

The following two assertions are equivalent for an o-minimal expansion of an ordered group $\mathcal M=(M,<,+,0,\ldots)$. There exists a definable bijection between a bounded interval and an unbounded interval. Any definable continuous…

Logic · Mathematics 2023-05-17 Masato Fujita

In "On o-minimal homotopy groups", o-minimal homotopy was developed for the definable category, proving o-minimal versions of the Hurewicz theorems and the Whitehead theorem. Here, we extend these results to the category of locally…

Logic · Mathematics 2008-12-12 Elias Baro , Margarita Otero

A note connecting arguments scattered in the extant literature proving that, in any o-minimal expansion of the real field, a definable family of sets has the property that the set of parameters corresponding to finite-volume fibers is…

Logic · Mathematics 2025-08-14 L. C. Brown

In this paper we completely characterize solvable real Lie groups definable in o-minimal expansions of the real field.

Logic · Mathematics 2015-06-29 Annalisa Conversano , Alf Onshuus , Sergei Starchenko

We define the notion of computability of F{\o}lner sets for finitely generated amenable groups. We prove, by an explicit description, that the Kharlampovich group, a finitely presented solvable group with unsolvable word problem, has…

Group Theory · Mathematics 2018-07-04 Matteo Cavaleri