English

Borel's Conjecture in Topological Groups

Logic 2012-07-06 v2 General Topology Group Theory

Abstract

We introduce a natural generalization of Borel's Conjecture. For each infinite cardinal number κ\kappa, let {\sf BC}κ_{\kappa} denote this generalization. Then BC0{\sf BC}_{\aleph_0} is equivalent to the classical Borel conjecture. Assuming the classical Borel conjecture, ¬BC1\neg{\sf BC}_{\aleph_1} is equivalent to the existence of a Kurepa tree of height 1\aleph_1. Using the connection of BCκ{\sf BC}_{\kappa} with a generalization of Kurepa's Hypothesis, we obtain the following consistency results: (1)If it is consistent that there is a 1-inaccessible cardinal then it is consistent that BC1{\sf BC}_{\aleph_1}. (2)If it is consistent that BC1{\sf BC}_{\aleph_1} holds, then it is consistent that there is an inaccessible cardinal. (3)If it is consistent that there is a 1-inaccessible cardinal with ω\omega inaccessible cardinals above it, then ¬BCω+(n<ω)BCn\neg{\sf BC}_{\aleph_{\omega}} \, +\, (\forall n<\omega){\sf BC}_{\aleph_n} is consistent. (4)If it is consistent that there is a 2-huge cardinal, then it is consistent that BCω{\sf BC}_{\aleph_{\omega}}. (5)If it is consistent that there is a 3-huge cardinal, then it is consistent that BCκ{\sf BC}_{\kappa} holds for a proper class of cardinals κ\kappa of countable cofinality.

Keywords

Cite

@article{arxiv.1107.5383,
  title  = {Borel's Conjecture in Topological Groups},
  author = {Fred Galvin and Marion Scheepers},
  journal= {arXiv preprint arXiv:1107.5383},
  year   = {2012}
}

Comments

15 pages

R2 v1 2026-06-21T18:42:45.626Z