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In this paper, we introduce the concept of graded extension dimension for a group graded ring R, denoted by gr.ext.dim(R). We prove that when R is strongly graded, its graded extension dimension coincides with the non-graded extension…

Category Theory · Mathematics 2025-11-18 Pei Luo , Zhongkui Liu

We consider categories of relational structures that fully embed every category of universal algebras, and prove a partial characterisation of these in terms of an infinitary variant of the notion of nowhere density of Ne\v{s}et\v{r}il and…

Logic · Mathematics 2023-03-24 Ioannis Eleftheriadis

Our main theorem classifies the Auslander-Reiten triangles according to properties of the morphisms involved. As a consequence, we are able to compute the mapping cone of an irreducible morphism. We finish by showing a technique for…

Representation Theory · Mathematics 2016-10-27 Edson Ribeiro Alvares , Sônia Maria Fernandes , Hernán Giraldo

Showing that the Ramsey property holds for a class of finite structures can be an extremely challenging task and a slew of sophisticated methods have been proposed in literature. In this paper we propose a new strategy to show that a class…

Combinatorics · Mathematics 2018-01-30 Dragan Masulovic

We prove a new characterization of the Ramsey property of categories in terms of a generalized form of K\H{o}nig's tree lemma. Afterwards, we discuss its applications to structural Ramsey theory. In particular, we provide a new proof of the…

Combinatorics · Mathematics 2025-08-18 Maximilian Hadek

This article highlights historical achievements in the partition theory of countable homogeneous relational structures, and presents recent work, current trends, and open problems. Exciting recent developments include new methods involving…

Logic · Mathematics 2021-10-05 Natasha Dobrinen

In this paper we investigate algebraic properties of big Ramsey degrees in categories satisfying some mild conditions. As the first nontrivial consequence of the generalization we advocate in this paper we prove that small Ramsey degrees…

Combinatorics · Mathematics 2025-11-27 Dragan Mašulović

We introduce the notion of a {\it semi-retraction}. Given two structures $\A$ and $\B$, $\A$ is a semi-retraction of $\B$ if there exist quantifier-free type respecting maps $f: \B \raw \A$ and $g: \A \raw \B$ such that $f \circ g$ is an…

Logic · Mathematics 2020-11-03 Lynn Scow

This paper introduces the concept of a productive notion of big Ramsey degree and showcases its versatility through a handful of applications. The main focus is notably providing sufficient conditions for the existence of a finite canonical…

Logic · Mathematics 2023-06-14 Keegan Dasilva Barbosa

In the 1970s, structural Ramsey theory emerged as a new branch of combinatorics. This development came with the isolation of the concepts of the $\mathbf{A}$-Ramsey property and Ramsey class. Following the influential…

Combinatorics · Mathematics 2025-11-03 Jan Hubička , Matěj Konečný

We investigate the structure and representation theory of finite-dimensional $\mathbb{Z}$-graded Lie algebras, including the corresponding root systems and Verma, irreducible, and Harish-Chandra modules. This extends the familiar theory for…

Representation Theory · Mathematics 2025-07-02 Mark D. Gould , Phillip S. Isaac , Ian Marquette , Jorgen Rasmussen

We prove that finite partial orders with a linear extension form a Ramsey class. Our proof is based on the fact that class of acyclic graphs has the Ramsey property and uses the partite construction.

Combinatorics · Mathematics 2017-03-03 Jaroslav Nešetřil , Vojtěch Rödl

In this paper we prove tight bounds on the combinatorial and topological complexity of sets defined in terms of $n$ definable sets belonging to some fixed definable family of sets in an o-minimal structure. This generalizes the…

Combinatorics · Mathematics 2014-02-26 Saugata Basu

It has become obvious in the recent development that the structural Ramsey property is a categorical property: it depends not only on the choice of objects, but also on the choice of morphisms involved. In this paper we explicitely put the…

Category Theory · Mathematics 2015-11-25 Dragan Masulovic , Lynn Scow

A category which generalises to higher dimensions many of the features of the Temperley-Lieb category is introduced.

Mathematical Physics · Physics 2007-05-23 Marcos Alvarez , Paul P. Martin

We explore the properties of non-piecewise syndetic sets with positive upper density, which we call "discordant", in countably infinite amenable (semi)groups. Sets of this kind are involved in many questions of Ramsey theory and manifest…

Combinatorics · Mathematics 2022-04-12 Vitaly Bergelson , Jake Huryn , Rushil Raghavan

One of the consequences of the Compactness Principle in structural Ramsey theory is that the small Ramsey degrees cannot exceed the corresponding big Ramsey degrees, thereby justifying the choice of adjectives. However, it is unclear what…

Logic · Mathematics 2024-07-30 Dragan Mašulović

The paper contains versions of the Strong Embedding Theorem and the Uniqueness Subgroup Theorem for groups of finite Morley rank and odd type which are needed for the study of permutations actions and modules in the finite Morley rank…

Group Theory · Mathematics 2011-12-01 Alexandre Borovik , Jeffrey Burdges , Ali Nesin

There is a long history of studying Ramsey theory using the algebraic structure of the Stone-\v{C}ech compactification of discrete semigroup. It has been shown that various Ramsey theoretic structures are contained in different algebraic…

General Topology · Mathematics 2021-08-12 Dibyendu De , Pintu Debnath , Sayan Goswami

Motivated by the structure of certain modules over the loop Virasoro Lie conformal algebra and the Lie structures of Schrodinger-Virasoro algebras, we construct a class of infinite rank Lie conformal algebras CSV (a, b), where a, b are…

Rings and Algebras · Mathematics 2016-09-21 Guangzhe Fan , Yucai Su , Chunguang Xia