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Bounding nonsplitting enumeration degrees. (English) Zbl 1131.03019

Ahmad has shown the existence of nonzero \(\Sigma^0_2\) enumeration degrees, i.e., enumeration degrees below \({\mathbf 0}_e'\) that are nonsplitting. The present paper shows that, in fact, every nonzero \(\Sigma^0_2\) enumeration degree lies above such a degree.

MSC:

03D30 Other degrees and reducibilities in computability and recursion theory
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References:

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