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Non-isolated quasi-degrees

✍ Scribed by Ilnur I. Batyrshin

Publisher
John Wiley and Sons
Year
2009
Tongue
English
Weight
167 KB
Volume
55
Category
Article
ISSN
0044-3050

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✦ Synopsis

Abstract

We show that non‐isolated from below 2‐c.e. Q ‐degrees are dense in the structure of c.e. Q ‐degrees. We construct a 2‐c.e. Q ‐degree, which can't be isolated from below not only by c.e. Q ‐degrees, but by any Q ‐degree. We also prove that below any c.e. Q ‐degree there is a 2‐c.e. Q ‐degree, which is non‐isolated from below and from above (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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