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Given a structure $M$ we introduce infinitary logic expansions, which generalise the Morleyisation. We show that these expansions are tame, in the sense that they preserve and reflect both the Embedding Ramsey Property (ERP) and the…

Logic · Mathematics 2023-06-29 Nadav Meir , Aris Papadopoulos

At the beginning of 1950's Erd\H os and Rado suggested the investigation of the Ramsey-type results where the number of colors is not finite. This marked the birth of the so-called canonizing Ramsey theory. In 1985 Pr\"omel and Voigt made…

Combinatorics · Mathematics 2017-12-08 Dragan Masulovic

We prove the existence and uniqueness of geometric models of local isometry classes of locally homogeneous spaces with sectional curvature $|\operatorname{sec}|\leq 1$. Moreover, we show that the set of geometric models is compact in the…

Differential Geometry · Mathematics 2021-01-19 Francesco Pediconi

In this paper we prove an $\infty$-categorical version of the reflection theorem of Ad\'amek-Rosick\'y. Namely, that a full subcategory of a presentable $\infty$-category which is closed under limits and $\kappa$-filtered colimits is a…

Algebraic Topology · Mathematics 2022-07-20 Shaul Ragimov , Tomer M. Schlank

In the course of classifying the homogeneous permutations, Cameron introduced the viewpoint of permutations as structures in a language of two linear orders, and this structural viewpoint is taken up here. The majority of this thesis is…

Logic · Mathematics 2018-05-14 Samuel Braunfeld

We show that every Hardy field extends to an $\omega$-free Hardy field. This result relates to classical oscillation criteria for second-order homogeneous linear differential equations. It is essential in [10], and here we apply it to…

Commutative Algebra · Mathematics 2026-03-11 Matthias Aschenbrenner , Lou van den Dries , Joris van der Hoeven

We study various notions of "tameness" for definably complete expansions of ordered fields. We mainly study structures with locally o-minimal open core, d-minimal structures, and dense pairs of d-minimal structures.

Logic · Mathematics 2010-03-19 Antongiulio Fornasiero

We develop category-theoretic framework for universal homogeneous objects, with some applications in the theory of Banach spaces, linear orderings, and in topology of compact spaces.

Category Theory · Mathematics 2013-03-12 Wieslaw Kubiś

For any cssc-crossed module a category is constructed, equipped with a structure and proved that this is a coherent categorical group. Together with a result of the previous paper, where to any categorical group the cssc-crossed module is…

Category Theory · Mathematics 2024-10-15 Tamar Datuashvili , Osman Mucuk , Nazmiye Alemdar , Tunçar Şahan

We survey recent developments concerning two properties of classes of finite structures: the Ramsey property and the extension property for partial automorphisms (EPPA).

Combinatorics · Mathematics 2020-10-13 Jan Hubička

Ramsey theory looks for regularities in large objects. Model theory studies algebraic structures as models of theories. The structural Ramsey theory combines these two fields and is concerned with Ramsey-type questions about certain…

Combinatorics · Mathematics 2018-05-22 Matěj Konečný

We prove some results on the border of Ramsey theory (finite partition calculus) and model theory. Also a beginning of classification theory of finite models in undertaken.

Logic · Mathematics 2016-09-06 Doug Ensley , Rami Grossberg

We prove that categories enriched in the Thomason model structure admit a model structure that is Quillen equivalent to the Bergner model structure on simplicial categories, providing a new model for (infinity,1)-categories. Along the way,…

Algebraic Topology · Mathematics 2023-11-20 Dmitri Pavlov

Consider a linear ordering equipped with a finite sequence of monadic predicates. If the ordering contains an interval of order type \omega or -\omega, and the monadic second-order theory of the combined structure is decidable, there exists…

Logic in Computer Science · Computer Science 2015-07-01 Alexis Bes , Alexander Rabinovich

A topological group $G$ is {\em sequentially $h$-complete} if all the continuous homomorphic images of $G$ are sequentially complete. In this paper we give necessary and sufficient conditions on a complete group for being compact, using the…

Group Theory · Mathematics 2011-09-27 Gábor Lukács

We prove a sharp structural result concerning finite colorings of pairs in well-founded trees.

Combinatorics · Mathematics 2019-05-17 R. M. Causey , C. Doebele

It was shown in \cite{sc12} that for a certain class of structures $\I$, $\I$-indexed indiscernible sets have the modeling property just in case the age of $\I$ is a Ramsey class. We expand this known class of structures from ordered…

Logic · Mathematics 2016-02-10 Lynn Scow

In this paper we provide purely categorical proofs of two important results of structural Ramsey theory: the result of M.\ Soki\'c that the free product of Ramsey classes is a Ramsey class and the result of M.\ Bodirsky, M.\Pinsker and T.\…

Category Theory · Mathematics 2023-01-18 Dragan Mašulović

Sabok showed that the set of codes for $G_\delta$ Ramsey positive subsets of $[\omega]^\omega$ is $\mathbf{\Sigma}^1_2$-complete. We extend this result by providing sufficient conditions for the set of codes for $G_\delta$ Ramsey positive…

Logic · Mathematics 2024-12-18 Allison Wang

We prove that the projective model structure on the category of unbounded cochain complexes extends naturally to the category of contractions. The proof is completely elementary and we do not assume familiarity with model categories.

Algebraic Topology · Mathematics 2017-03-10 Marco Manetti , Chiara Spagnoli