Small sets in dense pairs
Abstract
Let be an expansion of an o-minimal structure by a dense set , such that three tameness conditions hold. We prove that the induced structure on by eliminates imaginaries. As a corollary, we obtain that every small set definable in can be definably embedded into some , uniformly in parameters, settling a question from [10]. We verify the tameness conditions in three examples: dense pairs of real closed fields, expansions of by a dense independent set, and expansions by a dense divisible multiplicative group with the Mann property. Along the way, we point out a gap in the proof of a relevant elimination of imaginaries result in Wencel [17]. The above results are in contrast to recent literature, as it is known in general that does not eliminate imaginaries, and neither it nor the induced structure on admits definable Skolem functions.
Cite
@article{arxiv.1704.05802,
title = {Small sets in dense pairs},
author = {Pantelis E. Eleftheriou},
journal= {arXiv preprint arXiv:1704.05802},
year = {2018}
}