English

Consecutive singular cardinals and the continuum function

Logic 2016-02-10 v2

Abstract

We show that from a supercompact cardinal \kappa, there is a forcing extension V[G] that has a symmetric inner model N in which ZF + not AC holds, \kappa\ and \kappa^+ are both singular, and the continuum function at \kappa\ can be precisely controlled, in the sense that the final model contains a sequence of distinct subsets of \kappa\ of length equal to any predetermined ordinal. We also show that the above situation can be collapsed to obtain a model of ZF + not AC_\omega\ in which either (1) aleph_1 and aleph_2 are both singular and the continuum function at aleph_1 can be precisely controlled, or (2) aleph_\omega\ and aleph_{\omega+1} are both singular and the continuum function at aleph_\omega\ can be precisely controlled. Additionally, we discuss a result in which we separate the lengths of sequences of distinct subsets of consecutive singular cardinals \kappa\ and \kappa^+ in a model of ZF. Some open questions concerning the continuum function in models of ZF with consecutive singular cardinals are posed.

Keywords

Cite

@article{arxiv.1112.1890,
  title  = {Consecutive singular cardinals and the continuum function},
  author = {Arthur W. Apter and Brent Cody},
  journal= {arXiv preprint arXiv:1112.1890},
  year   = {2016}
}

Comments

to appear in the Notre Dame Journal of Formal Logic, issue 54:3, June 2013

R2 v1 2026-06-21T19:48:26.398Z