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Rupert wrote:
lugita15@xxxxxxxxx wrote:
I know that NF is different from both Zermelo set theory and TST.
Rather, NF is equivalent to TST plus an axiom scheme which asserts that
every formula phi is equivalent to phi+, which raises the types of all
the variables in phi by 1.
Are you sure about this? Is this result anywhere in the literature?
It's a famous result of Specker. You can find it at least in
Specker, E.P. Typical ambiguity. In Logic, methodology and
philosophy of science. Ed E. Nagel, Stanford University Press, 1962.
--
Aatu Koskensilta (aatu.koskensilta@xxxxxxxxx)
"Wovon man nicht sprechen kann, daruber muss man schweigen"
- Ludwig Wittgenstein, Tractatus Logico-Philosophicus
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