English

Non-linear iterations and higher splitting

Logic 2020-05-25 v1

Abstract

We show that generalized eventually narrow sequences on a strongly inaccessible cardinal κ\kappa are preserved under the Cummings-Shaleh non-linear iterations of the higher Hechler forcing on κ\kappa. Moreover assuming GCH, κ<κ=κ\kappa^{<\kappa}=\kappa, we show that: (1) if κ\kappa is strongly unfoldable, κ+β=cf(β)cf(δ)δμ\kappa^+\leq\beta=\hbox{cf}(\beta)\leq \hbox{cf}(\delta)\leq\delta\leq\mu and cf(μ)>κ\hbox{cf}(\mu)>\kappa,then there is a cardinal preserving generic extension in which s(κ)=κ+b(κ)=βd(κ)=δ2κ=μ.\mathfrak{s}(\kappa)=\kappa^+\leq\mathfrak{b}(\kappa)=\beta\leq\mathfrak{d}(\kappa)=\delta\leq 2^\kappa=\mu. (2) if κ\kappa is strongly inaccessible, λ>κ+\lambda>\kappa^+, then in the generic extension obtained as the <κ<\kappa-support iteration of κ\kappa-Hechler forcing of length λ\lambda there are no κ\kappa-towers of length λ\lambda.

Keywords

Cite

@article{arxiv.2005.11105,
  title  = {Non-linear iterations and higher splitting},
  author = {Ömer Faruk Bağ and Vera Fischer},
  journal= {arXiv preprint arXiv:2005.11105},
  year   = {2020}
}
R2 v1 2026-06-23T15:44:13.775Z