English

A parallel to the null ideal for inaccessible lambda. Part I

Logic 2017-01-20 v3

Abstract

It is well known to generalize the meagre ideal replacing aleph_0 by a (regular) cardinal lambda > aleph_0 and requiring the ideal to be lambda^+-complete. But can we generalize the null ideal? In terms of forcing, this means finding a forcing notion similar to the random real forcing, replacing aleph_0 by lambda, so requiring it to be (<lambda)-complete. Of course, we would welcome additional properties generalizing the ones of the random real forcing. Returning to the ideal (instead forcing) we may look at the Boolean Algebra of lambda-Borel sets modulo the ideal. Surprisingly we get an positive = existence answer for lambda a "mild" large cardinals: the weakly compact ones. We apply this to get consistency results on cardinal invariants for such lambda's. We shall deal with other cardinals more properties related forcing notions in a continuation.

Keywords

Cite

@article{arxiv.1202.5799,
  title  = {A parallel to the null ideal for inaccessible lambda. Part I},
  author = {Saharon Shelah},
  journal= {arXiv preprint arXiv:1202.5799},
  year   = {2017}
}
R2 v1 2026-06-21T20:25:20.733Z