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    Coanalytic ultrafilter bases.Jonathan Schilhan - 2022 - Archive for Mathematical Logic 61 (3-4):567-581.
    We study the definability of ultrafilter bases on \ in the sense of descriptive set theory. As a main result we show that there is no coanalytic base for a Ramsey ultrafilter, while in L we can construct \ P-point and Q-point bases. We also show that the existence of a \ ultrafilter is equivalent to that of a \ ultrafilter base, for \. Moreover we introduce a Borel version of the classical ultrafilter number and make some observations.
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  2. Generalised Pseudointersections.Jonathan Schilhan - 2019 - Mathematical Logic Quarterly 65 (4):479-489.
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    Tree Forcing and Definable Maximal Independent Sets in Hypergraphs.Jonathan Schilhan - forthcoming - Journal of Symbolic Logic:1-35.
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