Splitting families and the Noetherian type of $\beta\omega-\omega$

Abstract

Extending some results of Malykhin, we prove several independence results about base properties of $\beta\omega-\omega$ and its powers, especially the Noetherian type $Nt(\beta\omega-\omega)$, the least $\kappa$ for which $\beta\omega-\omega$ has a base that is $\kappa$-like with respect to containment. For example, $Nt(\beta\omega-\omega)$ is never less than the splitting number, but can consistently be that $\omega_1$, $2^\omega$, $(2^\omega)^+$, or strictly between $\omega_1$ and $2^\omega$. $Nt(\beta\omega-\omega)$ is also consistently less than the additivity of the meager ideal. $Nt(\beta\omega-\omega)$ is closely related to the existence of special kinds of splitting families.