The structure of pleasant ideals
Logic
2009-09-25 v1
Abstract
Normal ideals on regular uncountable cardinals are familiar objects. We investigate ideals that are pleasant--while a normal ideal is closed under arbitrary diagonal unions, a pleasant ideal is closed only under diagonal unions indexed by sets that are elements of the ideal. We show any selective ideal extending the nonstationary ideal must be normal.
Cite
@article{arxiv.math/9308203,
title = {The structure of pleasant ideals},
author = {Christopher Leary},
journal= {arXiv preprint arXiv:math/9308203},
year = {2009}
}