A recursion theoretic property of $\mathbf {\Sigma ^1_1}$ equivalence relations
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- by Howard Becker PDF
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Abstract:
Let $E$ be a $\mathbf {\Sigma ^1_1}$ equivalence relation on $2^\omega$ which does not have perfectly many equivalence classes. For $a \in 2^\omega$, define $L^a_E$ to be the set $\{[x]_E: (\exists y) (y \in [x]_E$ and $\omega _1^{\langle a,y \rangle } = \omega _1^a)\}$. For a Turing cone of $a$’s, $L^a_E$ is countable. This is proved assuming $\mathbf {\Pi }^1_2$-determinacy.References
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Additional Information
- Howard Becker
- Affiliation: Suite 3, 4711 Forest Drive, Columbia, South Carolina 29206
- MR Author ID: 33335
- Email: hsbecker@hotmail.com
- Received by editor(s): October 27, 2017
- Received by editor(s) in revised form: January 28, 2018
- Published electronically: July 23, 2018
- Communicated by: Heike Mildenberger
- © Copyright 2018 American Mathematical Society
- Journal: Proc. Amer. Math. Soc. 146 (2018), 4921-4926
- MSC (2010): Primary 03E15
- DOI: https://doi.org/10.1090/proc/14118
- MathSciNet review: 3856158