Displaying similar documents to “Borel Sets and Countable Models”

A Borel topos

Donovan H. Van Osdol (1981)

Cahiers de Topologie et Géométrie Différentielle Catégoriques

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Separating equivalence classes

Jindřich Zapletal (2018)

Commentationes Mathematicae Universitatis Carolinae

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Given a countable Borel equivalence relation, I introduce an invariant measuring how difficult it is to find Borel sets separating its equivalence classes. I evaluate these invariants in several standard generic extensions.