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A note on frame extensions

Published online by Cambridge University Press:  12 March 2014

Louise Hay*
Affiliation:
University of Illinois at Chicago Circle, Chicago, Illinois 60680

Extract

In [2] “recursive frames” were introduced as a means of extending relations R on the nonnegative integers to relations RΛ on the isols. In [1], this extension procedure was generalized by the introduction of “partial recursive frames”; the resulting extended relation on the isols was called RΛ. It was shown in [1] that the two extension procedures agree for recursive relations R, while RΛRΛ if R is . The case when R is , nonrecursive was left open. We show in this note that the extension procedures in fact agree for all relations R.

In the following, the notation and terminology is that of [1] and [2].

Theorem. If RXκQ is a recursively enumerable (r.e.) relation, then RΛ = RΛ.

Proof. Clearly RΛRΛ, since every recursive frame is partial recursive. To prove RΛRΛ, we give a uniform effective method for expanding any partial recursiveR-frame F to a recursiveR-frame G such that FG, so that So let F be a (nonempty) partial recursive R-frame, with CF(α) generated by . Let Rn denote the result of performing n steps in a fixed recursive enumeration of R. If g(α) is a partial recursive function, “g(α) is defined in n steps” means that in whichever coding of recursive computations is being used, a terminating computation for g with argument α has length ≤ n.

Type
Research Article
Copyright
Copyright © Association for Symbolic Logic 1972

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References

REFERENCES

[1]Ellentuck, E., The positive properties of isolic integers, this Journal (to appear).Google Scholar
[2]Nerode, A., Extensions to isols, Annals of Mathematics, vol. 73 (1961), pp. 362403.CrossRefGoogle Scholar