Journal of Symbolic Logic

On Σ₁-structural differences among finite levels of the Ershov hierarchy

Yue Yang and Liang Yu

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Abstract

We show that the structure ℛ of recursively enumerable degrees is not a Σ₁-elementary substructure of 𝒟n, where 𝒟n (n>1) is the structure of n-r.e. degrees in the Ershov hierarchy.

Article information

Source
J. Symbolic Logic, Volume 71, Issue 4 (2006), 1223-1236.

Dates
First available in Project Euclid: 20 November 2006

Permanent link to this document
https://projecteuclid.org/euclid.jsl/1164060453

Digital Object Identifier
doi:10.2178/jsl/1164060453

Mathematical Reviews number (MathSciNet)
MR2275857

Zentralblatt MATH identifier
1112.03038

Subjects
Primary: 03D25: Recursively (computably) enumerable sets and degrees

Citation

Yang, Yue; Yu, Liang. On Σ₁-structural differences among finite levels of the Ershov hierarchy. J. Symbolic Logic 71 (2006), no. 4, 1223--1236. doi:10.2178/jsl/1164060453. https://projecteuclid.org/euclid.jsl/1164060453


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