[FOM] Another pair of historical queries ...
Neil Tennant
neilt at mercutio.cohums.ohio-state.edu
Wed Dec 8 14:54:00 EST 2004
On 8 Dec 2004, Peter Smith wrote:
> a) Who first noticed that a consistent, axiomatized, negation-complete
> formal theory is decidable [decidable by the idiot brute force method of
> enumerating theorems and seeing what turns up].
A. Janiczak, "A remark concerning the decidability of complete theories',
Journal of Symbolic Logic 15, 1950, pp. 277-9.
> b) Who first saw that you could show that a `sufficiently strong'
> axiomatized formal theory T of arithmetic is undecidable [where
> `sufficiently strong' is defined in terms of the **intuitive** notion of
> decidability, and the proof proceeds by enumerating open wffs A_n(x) and
> defining a diagonal property D, where n is D iff T |- not-A_n(n), etc.
> etc.]
Probably one of Tarski, Mostowski and Robinson---of "Undecidable Theories"
fame?
Neil Tennant
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