Translator Disclaimer
November 2020 Weak Density and Nondensity among Transfinite Levels of the Ershov Hierarchy
Yong Liu, Cheng Peng
Notre Dame J. Formal Logic 61(4): 521-536 (November 2020). DOI: 10.1215/00294527-2020-0023

Abstract

We show that for any ω-r.e. degree d and n-r.e. degree b with d<b, there is an (ω+1)-r.e. degree a strictly between d and b. We also show that there is a maximal incomplete (ω+1)-r.e. degree. As a corollary, Dω is not a Σ1-elementary substructure of Dω+1.

Citation

Download Citation

Yong Liu. Cheng Peng. "Weak Density and Nondensity among Transfinite Levels of the Ershov Hierarchy." Notre Dame J. Formal Logic 61 (4) 521 - 536, November 2020. https://doi.org/10.1215/00294527-2020-0023

Information

Received: 9 February 2020; Accepted: 26 May 2020; Published: November 2020
First available in Project Euclid: 23 December 2020

Digital Object Identifier: 10.1215/00294527-2020-0023

Subjects:
Primary: 03D28

Rights: Copyright © 2020 University of Notre Dame

JOURNAL ARTICLE
16 PAGES

This article is only available to subscribers.
It is not available for individual sale.
+ SAVE TO MY LIBRARY

SHARE
Vol.61 • No. 4 • November 2020
Back to Top