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An infinite structure has the finite length property (over a given field) if, for each of its finite powers, chains of equivariant subspaces in the corresponding free vector space are bounded in length. Prior work showed that the countable…

Combinatorics · Mathematics 2026-05-22 Jingjie Yang , Mikołaj Bojańczyk , Bartek Klin

In this article, we provide a simple and systematic way to represent general (inhomogeneous) fractals that may look different at different scales and places. By using set-valued compression maps, we express these general fractals as…

Classical Analysis and ODEs · Mathematics 2024-06-04 Tynan Lazarus , Enrique G Alvarado , Qinglan Xia

General hyperbolic systems of balance laws with inhomogeneity in space and time in all constitutive functions are studied in the context of relative entropy. A framework is developed in this setting that contributes to a measure-valued weak…

Analysis of PDEs · Mathematics 2022-06-02 Cleopatra Christoforou

It is known that families of graphs with a semialgebraic edge relation of bounded complexity satisfy much stronger regularity properties than arbitrary graphs, and that they can be decomposed into very homogeneous semialgebraic pieces up to…

Logic · Mathematics 2016-02-25 Artem Chernikov , Sergei Starchenko

We continue the study of projective Fra\"{i}ss\'{e} limits of trees initiated by Charatonik and Roe and we construct many generalized Wa\.{z}ewski dendrites as the topological realization of a projective Fra\"{i}ss\'{e} limit of families of…

Logic · Mathematics 2024-01-17 Alessandro Codenotti , Aleksandra Kwiatkowska

We introduce the notion of limiting theories, giving examples and providing a sufficient condition under which the first order theory of a structure is the limit of the first order theories of a collection of substructures. We also give a…

Logic · Mathematics 2020-07-21 Samuel M. Corson

We present a new general framework for metrization of Gromov-Hausdorff-type topologies on non-compact metric spaces. We also give easy-to-check conditions for separability and completeness and hence the measure theoretic requirements are…

Metric Geometry · Mathematics 2025-09-08 Ryoichiro Noda

The Urysohn space is a separable complete metric space with two fundamental properties: (a) universality: every separable metric space can be isometrically embedded in it; (b) ultrahomogeneity: every finite isometry between two finite…

Metric Geometry · Mathematics 2017-12-05 David Bryant , André Nies , Paul Tupper

Given a countable, totally ordered commutative monoid $\mathcal{R}=(R,\oplus,\leq,0)$, with least element $0$, there is a countable, universal and ultrahomogeneous metric space $\mathcal{U}_\mathcal{R}$ with distances in $\mathcal{R}$. We…

Logic · Mathematics 2018-07-17 Gabriel Conant

For a finite lattice $\Lambda$, $\Lambda$-ultrametric spaces are a convenient language for describing structures equipped with a family of equivalence relations. When $\Lambda$ is finite and distributive, there exists a generic…

Logic · Mathematics 2025-11-21 Samuel Braunfeld

In the first part of this investigation, [Ha], we generalized a weighted distance function of [Li] and found necessary and sufficient conditions for it being a metric. In this paper some properties of this so-called M-relative metric are…

Metric Geometry · Mathematics 2007-05-23 Peter A. Hasto

This article is devoted to the analysis of necessary and/or sufficient conditions for metric regularity in terms of Demyanov-Rubinov-Polyakova quasidifferentials. We obtain new necessary and sufficient conditions for the local metric…

Optimization and Control · Mathematics 2020-11-19 M. V. Dolgopolik

Using contiguous relations we construct an infinite number of continued fraction expansions for ratios of generalized hypergeometric series 3F2(1). We establish exact error term estimates for their approximants and prove their rapid…

Classical Analysis and ODEs · Mathematics 2017-09-04 Akihito Ebisu , Katsunori Iwasaki

Persistent homology is a popular and useful tool for analysing finite metric spaces, revealing features that can be used to distinguish sets of unlabeled points and as input into machine learning pipelines. The famous stability theorem of…

Computational Geometry · Computer Science 2024-05-10 Philip Smith , Vitaliy Kurlin

The celebrated theorem of Kechris, Pestov and Todor\v{c}evi\'c connecting structural Ramsey theory with topological dynamics has as a consequence that the Fra\"{\i}ss\'e limit of a Ramsey class of non-trivial finite relational structures…

Logic · Mathematics 2025-12-08 Peter J. Cameron , Siavash Lashkarighouchani

This paper is about omitting types in logic of metric structures introduced by Ben Yaacov, Berenstein, Henson and Usvyatsov. While a complete type is omissible in some model of a countable complete theory if and only if it is not principal,…

Logic · Mathematics 2017-11-28 Ilijas Farah , Menachem Magidor

We realize the $\mathbb{F}_q$-algebra $M(\mathbb{F}_q)$ studied by von Neumann and Halperin as the Fra\"iss\'e limit of the class of finite-dimensional matrix algebras over a finite field $\mathbb{F}_q$ equipped with the rank metric. We…

Rings and Algebras · Mathematics 2021-05-24 Aaron Anderson

Big Ramsey degrees of finite structures are usually considered with respect to a Fra\"{i} ss\'e limit. Building mainly on the work of Devlin, Sauer, Laflamme and Van Th\'e, in this paper we consider structures which are not Fra\"{i} ss\'e…

Combinatorics · Mathematics 2018-07-06 Dragan Masulovic

The Fr\'echet mean is an important statistical summary and measure of centrality of data; it has been defined and studied for persistent homology captured by persistence diagrams. However, the complicated geometry of the space of…

Metric Geometry · Mathematics 2025-01-03 Yueqi Cao , Anthea Monod

A structure is called homogeneous if every isomorphism between finite substructures of the structure extends to an automorphism of the structure. Recently, P. J. Cameron and J. Ne\v{s}et\v{r}il introduced a relaxed version of homogeneity:…

Combinatorics · Mathematics 2010-01-06 Dragan Mašulović , Rajko Nenadov , Nemanja Škorić