Smooth Sets for a Borel Equivalence Relation
نویسنده
چکیده
We study some properties of smooth Borel sets with respect to a Borel equivalence relation, showing some analogies with the collection of countable sets from a descriptive set theoretic point of view. We found what can be seen as an analog of the hyperarithmetic points in the context of smooth sets. We generalize a theorem of Weiss from Z-actions to actions by arbitrary countable groups. We show that the cr-ideal of closed smooth sets is n{ non-Borel.
منابع مشابه
Smooth Sets for Borel Equivalence Relation
We study some properties of smooth Borel set with respect to a Borel equivalence relation, showing some analogies with the collection of countable sets from a descriptive set theoretic point of view. We found what can be seen as an analog of the hyperaritmectic reals in the context of smooth sets. We also present some results about the σ-ideal of closed smooth sets.
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