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COMPUTABILITY IN PARTIAL COMBINATORY ALGEBRAS

Published online by Cambridge University Press:  05 January 2021

SEBASTIAAN A. TERWIJN*
Affiliation:
DEPARTMENT OF MATHEMATICS RADBOUD UNIVERSITY NIJMEGEN P.O. BOX 9010, 6500 GL NIJMEGEN, THE NETHERLANDS E-mail: [email protected]
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Abstract

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We prove a number of elementary facts about computability in partial combinatory algebras (pca’s). We disprove a suggestion made by Kreisel about using Friedberg numberings to construct extensional pca’s. We then discuss separability and elements without total extensions. We relate this to Ershov’s notion of precompleteness, and we show that precomplete numberings are not 1–1 in general.

Type
Articles
Creative Commons
Creative Common License - CCCreative Common License - BY
This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (http://creativecommons.org/licenses/by/4.0), which permits unrestricted re-use, distribution, and reproduction in any medium, provided the original work is properly cited.
Copyright
© The Author(s), 2021. Published by Cambridge University Press

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