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On effectively discontinuous type-2 objects

Published online by Cambridge University Press:  12 March 2014

Thomas J. Grilliot*
Affiliation:
The Pennsylvania State University, University Park, Pennsylvania 16802

Extract

The notion of a recursive function with type-2 arguments was introduced by Kleene [4]. Soon E, the type-2 object that introduces numerical quantification, began to play a central role in the development of the theory. First, Kleene [4, XLVIII] proved that the hyperarithmetical functions are exactly the functions recursive in E. Later, Gandy [1, p. 14] proved the existence of a selection operator recursive in E (that is, some ψ(х, ), partial recursive in E, having the property that, if {х}(y, ) converges for some y, then ψ(х, ) converges and is such a y).

Type
Research Article
Copyright
Copyright © Association for Symbolic Logic 1971

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References

[1]Gandy, R. O., General recursive functionals of finite type and hierarchies of functions (mimeographed paper given at the symposium of mathematical logic held at the University of Clermont Ferrand in 06 1962).Google Scholar
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