Re: Question about Frege's Theorem

Aatu Koskensilta wrote:
Chris Menzel wrote:
On Mon, 25 Sep 2006 22:56:07 +0300, Aatu Koskensilta
<aatu.koskensilta@xxxxxxxxx> said:
As a sidenote, I, too, would require a "Henkin model" to contain all
the definable subsets - the unrestricted concept seems somewhat uninteresting.

That's how Enderton defines the notion of a general (i.e., Henkin)
structure, just FYI.

I'm not quite sure how to interpret that. Enderton defines a general
structure with or without the requirement that the definable subsets be
included?

--
Aatu Koskensilta (aatu.koskensilta@xxxxxxxxx)

"Wovon man nicht sprechen kann, daruber muss man schweigen"
- Ludwig Wittgenstein, Tractatus Logico-Philosophicus
Well, I looked it up in Manzano's "Extensions of First-Order Logic" and
it says that "All models of generalized semantics must include the set
of (parametrically) definable relations and thus the existence of these
relations are automatic validities of a 2-sorted system that should be
called second-order logic" I believe generalized semantics is the same
as Henkin Semantics, but I'm not sure.

.