# Sh:1132

• Saveliev, D. I., & Shelah, S. Ultrafilter extensions do not preserve elementary equivalence. Mathematical Logic Quarterly. To appear. arXiv: 1712.06198
• Abstract:
We show that there exist models {\mathcal M}_1 and {\mathcal M}_2 such that {\mathcal M}_1 elementarily embeds into {\mathcal M}_2 but their ultrafilter extension \beta({\mathcal M}_1) and \beta({\mathcal M}_2) are not elementarily equivalent.
@article{Sh:1132,
}