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The distribution of properly Σ20 e-degrees

Published online by Cambridge University Press:  12 March 2014

Stanislaw Bereznyuk ,
Richard Coles  and
Andrea Sorbi
Stanislaw Bereznyuk
Affiliation:
Institute of Mathematics, Novosibirsk State University, Novosibirsk, Russia, E-mail: stas@cclib.nsu.ru
Richard Coles
Affiliation:
Mathematics Department, Victoria University of Wellington, Wellington, New Zealand, E-mail: coles@cs.auckland.ac.nz Department of Computer Science, University of Auckland, Auckland, New Zealand, E-mail: coles@cs.auckland.ac.nz
Andrea Sorbi
Affiliation:
Department of Mathematics, University of Siena, Siena, Italy, E-mail: sorbi@unisi.it
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Abstract

We show that for every enumeration degree a < 0′e there exists an e-degree c such that a ≤ c < 0′e, and all degrees b, with c ≤ b < 0′e, are properly Σ20.

Information

Type
Research Article
Information
The Journal of Symbolic Logic , Volume 65 , Issue 1 , March 2000 , pp. 19 - 32
Copyright
Copyright © Association for Symbolic Logic 2000

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References

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