%0 Journal Article
%T The relation of rapid ultrafilters and Q-points to van der Waerden ideal
%A Jana Fla£¿kov¨¢
%J Mathematics
%D 2010
%I arXiv
%X 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.
%U http://arxiv.org/abs/1004.1879v2