English

On dp-minimal expansions of the integers II

Logic 2024-02-20 v1

Abstract

We first prove that if Z\mathcal{Z} is a dp-minimal expansion of (Z,+,0,1)\left(\mathbb{Z},+,0,1\right) which is not interdefinable with (Z,+,0,1,<)\left(\mathbb{Z},+,0,1,<\right), then every infinite subset of Z\mathbb{Z} definable in Z\mathcal{Z} is generic in Z\mathbb{Z}. Using this, we prove that if Z\mathcal{Z} is a dp-minimal expansion of (Z,+,0,1)\left(\mathbb{Z},+,0,1\right) with monster model GG such that G00G0G^{00}\neq G^{0}, then for some αR\Q\alpha\in\mathbb{R}\backslash\mathbb{Q}, the cyclic order on Z\mathbb{Z} induced by the embedding nnα+Zn\mapsto n\alpha+\mathbb{Z} of Z\mathbb{Z} in R/Z\mathbb{R}\big/\mathbb{Z} is definable in Z\mathcal{Z}. The proof employs the Gleason-Yamabe theorem for abelian groups.

Keywords

Cite

@article{arxiv.2402.11146,
  title  = {On dp-minimal expansions of the integers II},
  author = {Eran Alouf},
  journal= {arXiv preprint arXiv:2402.11146},
  year   = {2024}
}