[FOM] Elementary submodel

[Monroe Eskew]

Jan,

Why do you think it goes upward in complexity like that?  Write down the formula for there exists a blah cardinal; it has some complexity n.  Let kappa be the least blah cardinal.  Then we have an example of a formula of complexity n that cannot reflect to V_kappa; if it did then kappa would not be the least.

Monroe


On Jan 3, 2013, at 5:38 AM, <pax0 at seznam.cz> wrote:

> A question from set theory, book by Thomas Jech, third millennium edition:
> on page 386, exercise 20.10
> why we should prove it for 3, when proved for 1 implies
> V_kappa <_n V
> for all natural n?
> Thank you, Jan Pax
> 
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