Title

Borel Tukey Morphisms and Combinatorial Cardinal Invariants of the Continuum

Document Type

Article

Publication Date

1-2013

Abstract

We discuss the Borel Tukey ordering on cardinal invariants of the continuum. We observe that this ordering makes sense for a larger class of cardinals than has previously been considered. We then provide a Borel version of a large portion of van Douwen's diagram. For instance, although the usual proof of the inequality p≤b does not provide a Borel Tukey map, we show that in fact there is one. Afterwards, we revisit a result of Mildenberger concerning a generalization of the unsplitting and splitting numbers. Lastly, we use our results to give an embedding from the inclusion ordering on P(ω) into the Borel Tukey ordering on cardinal invariants.