English

More minimal non-$\sigma$-scattered linear orders

Logic 2023-12-29 v1

Abstract

Assuming an instance of the Brodsky-Rinot proxy principle holding at a regular uncountable cardinal κ\kappa, we construct 2κ2^\kappa-many pairwise non-embeddable minimal non-σ\sigma-scattered linear orders of size κ\kappa. In particular, in G\"odel's constructible universe LL, these linear orders exist for any regular uncountable cardinal κ\kappa that is not weakly compact. This extends a recent result of Cummings, Eisworth and Moore that takes care of all the successor cardinals of LL. At the level of 1\aleph_1, their work answered an old question of Baumgartner by constructing from \diamondsuit a minimal Aronszajn line that is not Souslin. Our use of the proxy principle yields the same conclusion from a weaker assumption which holds for instance in the generic extension after adding a single Cohen real to a model of CHCH.

Keywords

Cite

@article{arxiv.2312.17062,
  title  = {More minimal non-$\sigma$-scattered linear orders},
  author = {Roy Shalev},
  journal= {arXiv preprint arXiv:2312.17062},
  year   = {2023}
}

Comments

22 pages, comments are welcome

R2 v1 2026-06-28T14:03:46.453Z