Two real ultrafilters on \(\omega\)
The authors construct ultrafilters \(p,q\) on \(\omega\) such that (1) every compactification of \(\omega\cup \{p\}\) contains a copy of \(\beta\omega\) and (ii) \(q\) has an almost disjoint refinement \({\mathcal I}\) such that \(\omega\cup{\mathcal I}\cup \{q\}\) is a 0-dimensional scattered space with tightness \(c\).
scientific article; zbMATH DE number 1367522