[FOM] computable numbers, independent freindly logic
Aatu Koskensilta
aatu.koskensilta at xortec.fi
Sat Dec 27 17:03:23 EST 2003
George Kapoulas wrote:
>2) There is an approach for logic
>called independent friendly logic.
>Does anyone know if there is
>proof that the approach used by
>this logic cannot be expressed
>in 1st order logic,
>and references for this?
>
It's not entirely clear what "the approach used by this logic"
means. However, it's well known that the expressive power of
IF-logic (independence friendly) equals that of the Sigma^1_1
fragment of second order logic. An easy-going introduction to
these issues - along with more philosophical musings - can be
found in Jaakko Hintikka's Philosophy of Mathematics Revisited.
--
Aatu Koskensilta (aatu.koskensilta at xortec.fi)
"Wovon man nicht sprechen kann, daruber muss man schweigen"
- Ludwig Wittgenstein, Tractatus Logico-Philosophicus
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