English

Pseudo-finite sets, pseudo-o-minimality

Logic 2023-09-15 v2

Abstract

We give an example of two ordered structures M, N in the same language L with the same universe, the same order and admitting the same one-variable definable subsets such that M is a model of the common theory of o-minimal L-structures and N admits a definable, closed, bounded, and discrete subset and a definable injective self-mapping of that subset which is not surjective. This answers negatively two questions by Schoutens; the first being whether there is an axiomatization of the common theory of o-minimal structures in a given language by conditions on one-variable definable sets alone. The second being whether definable completeness and type completeness imply the pigeonhole principle. It also partially answers a question by Fornasiero asking whether definable completeness of an expansion of a real closed field implies the pigeonhole principle.

Keywords

Cite

@article{arxiv.1908.01660,
  title  = {Pseudo-finite sets, pseudo-o-minimality},
  author = {Nadav Meir},
  journal= {arXiv preprint arXiv:1908.01660},
  year   = {2023}
}

Comments

21 pages

R2 v1 2026-06-23T10:39:51.487Z