arXiv subjects
Publications and source records attributed to Jana Flašková.
This note answers the following question: Is it consistent that for an arbitrary tall summable ideal I_g there exists an I_g-ultrafilter which is not rapid? We show that assuming Martin's Axiom for σ-centered posets such ultrafilters exist for each tall summable ideal I_g.
We point out one of the differences between rapid ultrafilters and Q-points: Rapid ultrafilters may have empty intersection with van der Waerden ideal, whereas every Q-point has a non-empty intersection with van der Waerden ideal. Assuming Martin's axiom for countable posets we also construct a W-ultrafilter which is not a Q-point.