Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
4657814 | Topology and its Applications | 2016 | 11 Pages |
Abstract
We investigate the question of whether QQ carries an ultrafilter generated by perfect sets (such ultrafilters were called gruff ultrafilters by van Douwen). We prove that one can (consistently) obtain an affirmative answer to this question in three different ways: by assuming a certain parametrized diamond principle, from the cardinal invariant equality d=cd=c, and in the Random real model.
Keywords
Related Topics
Physical Sciences and Engineering
Mathematics
Geometry and Topology
Authors
David J. Fernández-Bretón, Michael Hrušák,