English

On Local Club Condensation

Logic 2021-04-02 v1

Abstract

We obtain results on the condensation principle called local club condensation. We prove that in extender models an equivalence between the failure of local club condensation and subcompact cardinals holds. This gives a characterization of κ\square_{\kappa} in terms of local club condensation in extender models. Assuming \gch\gch, given an interval of ordinals II we verify that iterating the forcing defined by Holy-Welch-Wu, we can preserve \gch\gch, cardinals and cofinalities and obtain a model where local club condensation holds for every ordinal in II modulo those ordinals which cardinality is a singular cardinal. We prove that if κ\kappa is a regular cardinal in an interval II, the above iteration provides enough condensation for the combinatorial principle \DlS(Π21)\Dl_{S}^{*}(\Pi^{1}_{2}), and in particular (S)\diamondsuit(S), to hold for any stationary SκS \subseteq \kappa.

Keywords

Cite

@article{arxiv.2104.00081,
  title  = {On Local Club Condensation},
  author = {Gabriel Fernandes},
  journal= {arXiv preprint arXiv:2104.00081},
  year   = {2021}
}
R2 v1 2026-06-24T00:45:02.675Z