Papers for

mathematicians and combinatorialists

Papers whose findings have a practical use for this group, as judged from the abstract. Open a paper to read what it means in practice.

Ramsey expansions completed for all finite S metric spaces

Ramsey expansions of $S$-metric spaces

Abstract: Let $S\subseteq \mathbb R^+$ be a subset of positive reals. We say that a metric space is an $S$-metric space if the range of the metric is a subset of $S\cup \{0\}$. In 2007, Delhommé, Laflamme, Pouzet, and Sauer characterized those sets $S$ for which the class of all finite $S$-metric spaces has the amalgamation property. Given an amalgamation class, a natural question is what its Ramsey expansion is. Ramsey expansions are known for classes of $S$-metric spaces for which $S\cup\{0\}$ carries a natural distance monoid structure, for example for $S=\mathbb Q^+$ or when $S$ is topologically closed. In this paper, we extend this result to all amalgamation classes of finite $S$-metric spaces, thereby completing the Ramsey-theoretic classification of amalgamation classes of finite $S$-metric spaces.

Mon 19 OctDiscrete Mathematics
The gist
The paper studies special spaces where distances come from a fixed set of positive numbers, called S-metric spaces. Previously, it was only known how to classify these spaces with certain properties, but the authors have now completed the picture for all cases where these spaces can be combined nicely. This helps understand how these spaces behave when expanded to reveal hidden structural patterns called Ramsey expansions. Their work finalizes the classification for all finite S-metric spaces that have a strong combination property.
Open → 2610.26167v1