Selection theorems and treeability
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- by Greg Hjorth PDF
- Proc. Amer. Math. Soc. 136 (2008), 3647-3653 Request permission
Abstract:
We show that domains of non-trivial $\Sigma ^1_1$ trees have $\Delta ^1_1$ members. Using this, we show that smooth treeable equivalence relations have Borel transversals, and essentially countable treeable equivalence relations have Borel complete countable sections. We show also that treeable equivalence relations which are ccc idealistic, measured, or generated by a Borel action of a Polish group have Borel complete countable sections.References
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Additional Information
- Greg Hjorth
- Affiliation: Department of Mathematics and Statistics, University of Melbourne, Parkville, 3010 Victoria, Australia
- Email: greg.hjorth@gmail.com
- Received by editor(s): November 20, 2006
- Published electronically: May 22, 2008
- Additional Notes: The author gratefully acknowledges partial support from the Australian Research Council.
- Communicated by: Julia Knight
- © Copyright 2008
American Mathematical Society
The copyright for this article reverts to public domain 28 years after publication. - Journal: Proc. Amer. Math. Soc. 136 (2008), 3647-3653
- MSC (2000): Primary 03E15
- DOI: https://doi.org/10.1090/S0002-9939-08-09548-8
- MathSciNet review: 2415050