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Results tagged with descriptive-set-theory
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user 497904
Descriptive Set Theory is the study of definable subsets of Polish spaces, where definable is taken to mean from the Borel or projective hierarchies. Other topics include infinite games and determinacy, definable equivalence relations and Borel reductions between them, Polish groups, and effective descriptive set theory.
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Is Borel cardinality the same as cardinality under determinacy?
Suppose $E,F$ are Borel equivalence relations on Polish spaces $X,Y$, respectively. Under strong enough determinacy axioms, is it true that $E$ Borel reduces to $F$ iff there is an injective map from …
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Strength of Borel determinacy
In this blog post by Gowers on Borel determinacy, Andres Caicedo says the following in a comment (slightly rephrased).
Let $\mathsf{ZFC^-}$ be $\mathsf{ZFC}$ without power set and $\mathsf{ZC^-}$ be …
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