Publication at Protestant Theological Faculty, Faculty of Mathematics and Physics, Faculty of Arts |
2011
Abstract
Forcing notions of the type () which do not add reals naturally add ultrafilters on ω. We investigate what classes of ultrafilters can be added in this way when is a definable ideal.
In particular, we show that if is an F σ P-ideal the generic ultrafilter will be a P-point without rapid RK-predecessors which is not a strong P-point. This provides an answer to long standing open questions of Canjar and Laflamme.