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We study countable embedding-universal and homomorphism-universal structures and unify results related to both of these notions. We show that many universal and ultrahomogeneous structures allow a concise description (called here a finite…

Combinatorics · Mathematics 2010-09-06 Jan Hubicka

A topology is defined on the mapping class group of a compact connected orientable surface. It is shown that a notion of "genericity" on subsets of the mapping class group arises from this definition. Many plausible results follow from this…

Geometric Topology · Mathematics 2025-08-06 Ingrid Irmer

This paper is a contribution to graded model theory, in the context of mathematical fuzzy logic. We study characterizations of classes of graded structures in terms of the syntactic form of their first-order axiomatization. We focus on…

Logic · Mathematics 2019-01-08 Guillermo Badia , Vicent Costa , Pilar Dellunde , Carles Noguera

We study $\omega$-categorical $MS$-measurable structures. Our main result is that a class of $\omega$-categorical Hrushovski constructions, supersimple of finite $SU$-rank is not $MS$-measurable. These results complement the work of Evans…

Logic · Mathematics 2022-11-29 Paolo Marimon

A standard combinatorial construction, due to Kontsevich, associates to any A-infinity algebra with an invariant inner product, an inhomogeneous class in the cohomology of the moduli spaces of Riemann surfaces with marked points. We…

Quantum Algebra · Mathematics 2007-05-23 Alastair Hamilton , Andrey Lazarev

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

We study model geometries of finitely generated groups. If a finitely generated group does not contain a non-trivial finite rank free abelian commensurated subgroup, we show any model geometry is dominated by either a symmetric space of…

Group Theory · Mathematics 2024-09-06 Alex Margolis

We investigate the local structure of the space $\mathcal{M}$ consisting of isometry classes of compact metric spaces, endowed with the Gromov-Hausdorff metric. We consider finite metric spaces of the same cardinality and suppose that these…

Metric Geometry · Mathematics 2016-11-15 Alexander O. Ivanov , Alexey A. Tuzhilin

We study when a union of saturated models is saturated in the framework of tame abstract elementary classes (AECs) with amalgamation. We prove: $\mathbf{Theorem}$ If $K$ is a tame AEC with amalgamation satisfying a natural definition of…

Logic · Mathematics 2017-04-13 Will Boney , Sebastien Vasey

In a relational language consisting of a single relation $ R, $ we investigate pseudofiniteness of certain Hrushovski constructions obtained via predimension functions. It is notable that the arity of the relation $ R $ plays a crucial role…

Logic · Mathematics 2025-10-16 Ali N. Valizadeh , Massoud Pourmahdian

We construct a geometric model for the mapping class group M of a non-exceptional oriented surface of finite type and use it to show that the action of M on the compact Hausdorff space of complete geodesic laminations is topologically…

Group Theory · Mathematics 2008-03-19 Ursula Hamenstaedt

We give an almost entirely model-theoretic account of both Ramsey classes of finite structures and of generalized indiscernibles as studied in special cases in (for example) [7], [9]. We understand "theories of indiscernibles" to be special…

Logic · Mathematics 2012-10-30 Cameron Donnay Hill

First we introduce a generalization of symmetric spaces to parabolic geometries. We provide construction of such parabolic geometries starting with classical symmetric spaces and we show that all regular parabolic geometries with smooth…

Differential Geometry · Mathematics 2012-07-30 Jan Gregorovič

This text is devoted to the systematic study of relative properties in the context of Berkovich analytic spaces. We first develop a theory of flatness in this setting. After having shown through a counter-example that naive flatness cannot…

Algebraic Geometry · Mathematics 2017-10-10 Antoine Ducros

In this paper, we introduce the notions of pre-uniform spaces and pre-proximities and investigate some basic properties about them, where the definition of pre-uniformity here is different with the pre-uniformities which are studied in…

General Topology · Mathematics 2022-11-29 Fucai Lin , Yufan Xie , Ting Wu , Meng Bao

We study abstract elementary classes (AECs) that, in $\aleph_0$, have amalgamation, joint embedding, no maximal models and are stable (in terms of the number of orbital types). Assuming a locality property for types, we prove that such…

Logic · Mathematics 2018-05-31 Saharon Shelah , Sebastien Vasey

We study the first-order almost-sure theories for classes of finite structures that are specified by homomorphically forbidding a set $\mathcal{F}$ of finite structures. If $\mathcal{F}$ consists of undirected graphs, a full description of…

Combinatorics · Mathematics 2024-06-24 Manuel Bodirsky , Colin Jahel

The paper contains a general construction which produces new examples of non simply-connected smooth projective surfaces. We analyze the resulting surfaces and their fundamental groups. Many of these fundamental groups are expected to be…

alg-geom · Mathematics 2008-02-03 Fedor Bogomolov , Ludmil Katzarkov

We examine the topological dynamics of the automorphism groups of omega-categorical sparse graphs resulting from Hrushovski constructions. Specifically, we consider the fixed points on type spaces property, which a structure M has if, for…

Logic · Mathematics 2024-08-14 Rob Sullivan

Let $M$ be strongly minimal and constructed by a `Hrushovski construction'. If the Hrushovski algebraization function $\mu$ is in a certain class ${\mathcal T}$ ($\mu$ triples) we show that for independent $I$ with $|I| >1$, ${\rm…

Logic · Mathematics 2024-05-01 John T. Baldwin , Viktor V. Verbovskiy
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