Monotone hulls for N cap M
Logic
2014-07-18 v2
Abstract
Using the method of decisive creatures (math.LO/0601083) we show the consistency of "there is no increasing omega_2 --chain of Borel sets and non(N)=non(M)= omega_2=2^omega". Hence, consistently, there are no monotone hulls for the ideal M cap N . This answers Balcerzak and Filipczak. Next we use FS iteration with partial memory to show that there may be monotone Borel hulls for the ideals M, N even if they are not generated by towers.
Cite
@article{arxiv.1007.5368,
title = {Monotone hulls for N cap M},
author = {Andrzej Roslanowski and Saharon Shelah},
journal= {arXiv preprint arXiv:1007.5368},
year = {2014}
}