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Ramseyan ultrafilters

Lorenz Halbeisen
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Abstract

We investigate families of partitions of omega which are related to special coideals, so-called happy families, and give a dual form of Ramsey ultrafilters in terms of partitions. The combinatorial properties of these partition-ultrafilters, which we call Ramseyan ultrafilters, are similar to those of Ramsey ultrafilters. For example it will be shown that dual Mathias forcing restricted to a Ramseyan ultrafilter has the same features as Mathias forcing restricted to a Ramsey ultrafilter. Further we introduce an ordering on the set of partition-filters and consider the dual form of some cardinal characteristics of the continuum.

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BibTeXRIS

Lorenz Halbeisen. 2001-09-16. Ramseyan ultrafilters. https://arxiv.org/abs/math/0109102

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