English

Nonproper Products

Logic 2014-02-26 v3

Abstract

We show that there exist two proper creature forcings having a simple (Borel) definition, whose product is not proper. We also give a new condition ensuring properness of some forcings with norms.

Keywords

Cite

@article{arxiv.0905.0526,
  title  = {Nonproper Products},
  author = {Andrzej Roslanowski and Saharon Shelah and Otmar Spinas},
  journal= {arXiv preprint arXiv:0905.0526},
  year   = {2014}
}
R2 v1 2026-06-21T12:58:11.327Z