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On the density of the pseudo-isolated degrees

Published online by Cambridge University Press:  08 March 2004

Guohua Wu
Guohua Wu
Affiliation:
School of Mathematical and Computing Sciences, Victoria University of Wellington, P.O. Box 600, Wellington, New Zealand. E-mail: wu@mcs.vuw.ac.nz
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Abstract

A d.c.e. (2-computably enumerable) degree d is pseudo-isolated if d itself is non-isolated (in the sense that no computably enumerable (c.e.) degree below d can bound the c.e. degrees below d) and there is a d.c.e. degree \textbf{b} < \textbf{d} bounding all c.e. degrees below d. We prove in this paper that the pseudo-isolated degrees are densely distributed in the c.e. degrees.

Keywords

non-isolated degreespseudo-isolated degreesdensity03D2503D28
Type
Research Article
Information
Proceedings of the London Mathematical Society , Volume 88 , Issue 2 , March 2004 , pp. 273 - 288
Copyright
2004 London Mathematical Society

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