Sh:1132

• Saveliev, D. I., & Shelah, S. (2019). Ultrafilter extensions do not preserve elementary equivalence. MLQ Math. Log. Q., 65(4), 511–516. arXiv: 1712.06198 MR: 4057949
• 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.
• published version (6p)

@article{Sh:1132,
 author = {Saveliev, Denis I. and Shelah, Saharon},
 title = {{Ultrafilter extensions do not preserve elementary equivalence}},
 journal = {MLQ Math. Log. Q.},
 fjournal = {MLQ. Mathematical Logic Quarterly},
 volume = {65},
 number = {4},
 year = {2019},
 pages = {511--516},
 issn = {0942-5616},
 mrnumber = {4057949},
 mrclass = {03C55 (03C30 03C80 54D35 54D80 54H10)},
 note = {\href{https://arxiv.org/abs/1712.06198}{arXiv: 1712.06198}},
 arxiv_number = {1712.06198}
}