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Almost any reasonable class of finite relational structures has the Ramsey property or a precompact Ramsey expansion. In contrast to that, the list of classes of finite algebras with the precompact Ramsey expansion is surprisingly short. In…

Combinatorics · Mathematics 2023-03-13 Dragan Masulovic

This paper investigates big Ramsey degrees of unrestricted relational structures in (possibly) infinite languages. Despite significant progress in the study of big Ramsey degrees, the big Ramsey degrees of many classes of structures with…

In this paper we consider big Ramsey degrees of finite chains in countable ordinals. We prove that a countable ordinal has finite big Ramsey degrees if and only if it is smaller than $\omega^\omega$. Big Ramsey degrees of finite chains in…

Combinatorics · Mathematics 2019-07-29 Dragan Mašulović , Branislav Šobot

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 prove that the universal homogeneous 3-uniform hypergraph has finite big Ramsey degrees. This is the first case where big Ramsey degrees are known to be finite for structures in a non-binary language. Our proof is based on the vector (or…

Combinatorics · Mathematics 2021-07-06 Martin Balko , David Chodounský , Jan Hubička , Matěj Konečný , Lluis Vena

In this paper we show that a countable structure admitting a finite monomorphic decomposition has finite big Ramsey degrees if and only if so does every monomorphic part in its minimal monomorphic decomposition. The necessary prerequisite…

Logic · Mathematics 2026-05-21 Dragan Mašulović , Veljko Toljić

Classical Ramsey theory has successfully extended to relational structures, yielding a wealth of results that have profoundly influenced other areas of mathematics. Interestingly, the same development has not occurred in the case of dual…

Combinatorics · Mathematics 2025-07-02 Aleksa Džuklevski , Dragan Mašulović

We characterize the big Ramsey degrees of free amalgamation classes in finite binary languages defined by finitely many forbidden irreducible substructures, thus refining the recent upper bounds given by Zucker. Using this characterization,…

Generalizing and simplifying recent work of Dobrinen, we show that if $\mathcal{L}$ is a finite binary relational language and $\mathcal{F}$ is a finite set of finite irreducible $\mathcal{L}$-structures, then the class $\mathcal{K} =…

Logic · Mathematics 2022-07-12 Andy Zucker

Ramsey's theorem states that for all finite colorings of an infinite set, there exists an infinite homogeneous subset. What if we seek a homogeneous subset that is also order-equivalent to the original set? Let $S$ be a linearly ordered set…

Combinatorics · Mathematics 2025-11-11 Joanna Boyland , William Gasarch , Nathan Hurtig , Robert Rust

We formulate a property strengthening the Disjoint Amalgamation Property and prove that every Fraisse structure in a finite relational language with relation symbols of arity at most two having this property has finite big Ramsey degrees…

Combinatorics · Mathematics 2021-09-14 Rebecca Coulson , Natasha Dobrinen , Rehana Patel

In recent years, there has been much progress in the field of structural Ramsey theory, in particular in the study of big Ramsey degrees. In all known examples of infinite structures with finite big Ramsey degrees, there is in fact a single…

Logic · Mathematics 2025-10-01 Jan Hubička , Andy Zucker

Ramsey algebras are algebras that induce Ramsey spaces, which are generalizations of the Ellentuck space and Milliken's space. Previous work suggests a possible local version of Ramsey algebras induced by infinite sequences. Hence, we…

Logic · Mathematics 2017-04-13 Wen Chean Teh , Zu Yao Teoh

Big Ramsey degrees of Fra\"iss\'e limits of finitely constrained free amalgamation classes in finite binary languages have been recently fully characterised by Balko, Chodounsk\'y, Dobrinen, Hubi\v{c}ka, Kone\v{c}n\'y, Vena, and Zucker. A…

Combinatorics · Mathematics 2025-10-01 Jan Hubička , Matěj Konečný , Štěpán Vodseďálek , Andy Zucker

We show that the big Ramsey degrees of every countable universal $u$-uniform $\omega$-edge-labeled hypergraph are infinite for every $u\geq 2$. Together with a recent result of Braunfeld, Chodounsk\'y, de Rancourt, Hubi\v{c}ka, Kawach, and…

Combinatorics · Mathematics 2025-10-01 Jan Hubička , Matěj Konečný , Stevo Todorcevic , Andy Zucker

One way of studying a relational structure is to investigate functions which are related to that structure and which leave certain aspects of the structure invariant. Examples are the automorphism group, the self-embedding monoid, the…

Logic · Mathematics 2011-05-31 Manuel Bodirsky , Michael Pinsker

In this paper we present a simple approach to big Ramsey combinatorics of the Cantor set $2^\omega$. Using Infinite Dual Ramsey Theorem of Carlson and Simpson, we show that $2^\omega$, viewed as a topological space, has finite big Ramsey…

Logic · Mathematics 2026-02-24 Dragan Mašulović

We develop an algebraic language theory based on the notion of an Eilenberg--Moore algebra. In comparison to previous such frameworks the main contribution is the support for algebras with infinitely many sorts and the connection to logic…

Formal Languages and Automata Theory · Computer Science 2023-06-22 Achim Blumensath

We study varieties of certain ordered $\Sigma$-algebras with restricted completeness and continuity properties. We give a general characterization of their free algebras in terms of submonads of the monad of $\Sigma$-coterms. Varieties of…

Logic in Computer Science · Computer Science 2023-06-22 Zoltan Esik , Dexter Kozen

We prove that each finite chain in the two-branching countable ultrahomogeneous pseudotree has finite big Ramsey degrees. This is in contrast to the recent result of Chodounsk\'{y}, Eskew, and Weinert that antichains of size two have…

Logic · Mathematics 2026-03-10 David Chodounský , Natasha Dobrinen , Thilo Weinert
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