# Sh:642

• Brendle, J., & Shelah, S. (1999). Ultrafilters on \omega—their ideals and their cardinal characteristics. Trans. Amer. Math. Soc., 351(7), 2643–2674.
• Abstract:
For a free ultrafilter \mathcal U on \omega we study several cardinal characteristics which describe part of the combinatorial structure of \mathcal U. We provide various consistency results; e.g. we show how to force simultaneously many characters and many \pi–characters. We also investigate two ideals on the Baire space \omega^\omega naturally related to \mathcal U and calculate cardinal coefficients of these ideals in terms of cardinal characteristics of the underlying ultrafilter.
• published version (32p)
Bib entry
@article{Sh:642,
author = {Brendle, J{\"o}rg and Shelah, Saharon},
title = {{Ultrafilters on $\omega$---their ideals and their cardinal characteristics}},
journal = {Trans. Amer. Math. Soc.},
fjournal = {Transactions of the American Mathematical Society},
volume = {351},
number = {7},
year = {1999},
pages = {2643--2674},
issn = {0002-9947},
mrnumber = {1686797},
mrclass = {03E05 (03E35)},
doi = {10.1090/S0002-9947-99-02257-6},
note = {\href{https://arxiv.org/abs/math/9710217}{arXiv: math/9710217}},
arxiv_number = {math/9710217}
}