Dense ideals

Abstract

In this paper, we obtain the consistency, relative to large cardinals, of the existence of dense ideals on every successor of a regular cardinal simultaneously. Using a consequent transfer principle, we show that in this model there is a $\sigma$-complete, $\aleph_1$-dense ideal on $\aleph_{n+1}$ for every $n < \omega$, answering a question of Foreman. Using this construction we show the consistency of the existence of various irregular ultrafilters on $\omega_n$, the consistency of the Foreman-Laver reflection property for the chromatic number of graphs for all possible pairs of cardinals below $\aleph_\omega$, and the simultaneous consistency of the partition hypotheses $\mathrm{PH}_n(\omega_m)$ for $n < m$.