Article ID Journal Published Year Pages File Type
4657814 Topology and its Applications 2016 11 Pages PDF
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
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