  We developed the theory of deterministic ideals and present a systematic
study of the pseudo-intersection property with respect to an ideal introduced
in \cite{TomNatasha2}. We apply this theory to prove that for any two
ultrafilters $U,V$ on $\omega$, $U\cdot V\equiv_T V\cdot U$. Additionally, we
analyze the class of ultrafilters which are Tukey above $\omega^\omega$. Our
theory applies the study of the Tukey types of a general sum of ultrafilters,
which, as evidenced by the results of this paper, can be quite complex.
Finally, we introduce the hierarchy of $\alpha$-almost rapid ultrafilters. We
prove that it is consistent for them to form a strictly wider class than the
rapid ultrafilters, and give an example of a non-rapid $p$-point which is Tukey
above $\omega^\omega$. This answers several questions from previous papers on
the subject.
