# Analytic countably splitting families

@article{Spinas2004AnalyticCS, title={Analytic countably splitting families}, author={Otmar Spinas}, journal={Journal of Symbolic Logic}, year={2004}, volume={69}, pages={101 - 117} }

Abstract A family A ⊆ (ω) is called countably splitting if for every countable F ⊆ [ω]ω, some element of A splits every member of F. We define a notion of a splitting tree, by means of which we prove that every analytic countably splitting family contains a closed countably splitting family. An application of this notion solves a problem of Blass. On the other hand we show that there exists an Fσ splitting family that does not contain a closed splitting family.

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