FOM: completeness theorem for stratification?
Stephen G Simpson
simpson at math.psu.edu
Sat Apr 15 17:22:15 EDT 2000
Thomas Forster (FOM, 13 Apr 2000):
> a formula is (equivlent to a) stratified formula iff the class of
> its models is closed under [ the Rieger-Bernays permutation ]
> construction. A bit of good old-fashioned model theory!
OK, very interesting. And please do send me the offprints.
Where does this leave us with respect to my earlier question (FOM, 7
Mar 2000) about the set-theoretic intuition? Is there a clear and
convincing picture which underlies NF, similar to how the picture of
the cumulative hierarchy underlies ZFC?
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