[FOM] The semantics of set theory

[Ralf Schindler]

On Thu, 3 Oct 2002, Kanovei wrote:

> Generally, there is no way to define ZFC-truth other than to 
> extend the language of ZFC. 
> Three typical methods are known. 
[...]
> Third, consider a second-order impredicative theory of classes. 

One doesn't need an *im*predicative theory of classes here, one can
do with predicative classes. (A class is predicative iff it can be
defined by a fmla of set theory + parameters for sets.) --Ralf

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Ralf Schindler                                Phone: +43-1-4277-50511
Institut fuer Formale Logik                     Fax: +43-1-4277-50599
Universitaet Wien                      E-mail: rds at logic.univie.ac.at
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