Re: question about categoricity
- From: "Per Freem" <perfreem@xxxxxxxxx>
- Date: 27 Nov 2005 22:53:40 -0800
Torkel Franzen wrote:
> "Per Freem" <perfreem@xxxxxxxxx> writes:
>
>
> > but since Chris's example involves expanding the language of the first
> > structure (by adding another constant to it), [...]
>
> There was no added constant, just an added element in the domain.
> Quoting his response: " Suppose B's domain is Nat U {you} and 'd_i'
> denotes i in B, for all i, and nothing denotes you in B."
yes this is true i was confusing the proof from Enderton of the same
claim (where a constant is added) with Chris's. but if adding an
element is all it takes, what would stop us from applying this
technique to show that very same theory is not \Aleph_{1}-categorical?
it shouldn't be possible since that theory /is/ \Aleph_{1}-categorical
but i'm just not sure where this technique would fail in this case?
.
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