I[omega_2] can be the nonstationary ideal on Cof(omega_1)
Logic
2007-05-23 v4
Abstract
We answer a question of Shelah by showing that it is consistent that every set of ordinals of cofinality omega_1 in I[omega_2] is nonstationary if and only if it is consistent that that there is a kappa^+ Mahlo cardinal kappa.
Cite
@article{arxiv.math/0407225,
title = {I[omega_2] can be the nonstationary ideal on Cof(omega_1)},
author = {William J. Mitchell},
journal= {arXiv preprint arXiv:math/0407225},
year = {2007}
}
Comments
version 4 of the paper has been extensively revised in response to the referee report from TAMS. I expect it to appear in TAMS