Russian Mathematics

, Volume 54, Issue 12, pp 51–58 | Cite as

Decomposability of low 2-computably enumerable degrees and turing jumps in the Ershov hierarchy

  • M. Kh. FaizrakhmanovEmail author


In this paper we prove the following theorem: For every notation of a constructive ordinal there exists a low 2-computably enumerable degree that is not splittable into two lower 2-computably enumerable degrees whose jumps belong to the corresponding Δ-level of the Ershov hierarchy.

Key words and phrases

low degrees 2-computably enumerable degrees Ershov hierarchy Turing jumps constructive ordinals 


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Copyright information

© Allerton Press, Inc. 2010

Authors and Affiliations

  1. 1.Kazan State UniversityKazanRussia

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