Submission date: 29 August 2021

Abstract:

We give a flexible method for constructing a wide variety of limits of betweenness relations. This unifies work of Adeleke, who constructed a Jordan group preserving a limit of betweenness relations, and Bhattacharjee and Macpherson who gave an alternative method using a Fraïssé-type construction.
A key ingredient in their work is the notion of a tree of B-sets. We employ this, and extend its use to a wider class of examples.

Mathematics Subject Classification:

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Full text arXiv 2108.12904: pdf, ps.