English

Small u(kappa) at singular kappa with compactness at kappa++

Logic 2019-11-01 v1

Abstract

We show that the tree property, stationary reflection and the failure of approachability at κ++\kappa^{++} are consistent with u(κ)=κ+<2κ\mathfrak{u}(\kappa) = \kappa^+ < 2^\kappa, where κ\kappa is a singular strong limit cardinal with the countable or uncountable cofinality. As a by-product, we show that if λ\lambda is a regular cardinal, then stationary reflection at λ+\lambda^+ is indestructible under all λ\lambda-cc forcings (out of general interest, we also state a related result for the preservation of club stationary reflection).

Keywords

Cite

@article{arxiv.1910.14391,
  title  = {Small u(kappa) at singular kappa with compactness at kappa++},
  author = {Radek Honzik and Sarka Stejskalova},
  journal= {arXiv preprint arXiv:1910.14391},
  year   = {2019}
}

Comments

20 pages, submitted

R2 v1 2026-06-23T12:00:40.522Z