On the density of the pseudo-isolated degrees

• Autores: Guohua Wu
• Localización: Proceedings of the London Mathematical Society, ISSN 0024-6115, Vol. 88, Nº 2, 2004, págs. 273-288
• Idioma: inglés
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• Resumen

  • 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.