English

Separating Models by Formulas and the Number of Countable Models

Logic 2012-11-28 v2

Abstract

We indicate a way of distinguishing between structures, for which, two structures are said to be separable.Being separable implies being non-isomorphic. We show that for any first order theory TT in a countable language, if it has an uncountable set of countable models that are pairwise separable, then actually it has such a set of size 202^{\aleph_0}. Our result follows trivially assuming the Continuum Hypothesis (CHCH). We work here in ZFCZFC (only without CHCH).

Keywords

Cite

@article{arxiv.1211.5441,
  title  = {Separating Models by Formulas and the Number of Countable Models},
  author = {Mohammad Assem},
  journal= {arXiv preprint arXiv:1211.5441},
  year   = {2012}
}
R2 v1 2026-06-21T22:43:02.249Z