Talk:Truth-value semantics

Theorem of Beth
I'm interested to read about the theorem of Beth alluded to in the article. It certainly isn't true that in ordinary first-order logic, anonymous elements of the domain can be ignored; for example the real numbers satisfy $$\exists x ( x^2 = 2)$$ in the language of rings, but there is no constant symbol for either root. So I am curious what context Beth was working in that made it possible to avoid this issue. &mdash; Carl (CBM · talk) 13:15, 3 May 2008 (UTC)


 * Technically there is a restriction on the size of the set of individual constants for the theorem to hold, viz. by Lowenheim-Skolem theorem, at least aleph-null. As per your particular example, the article is misleading, since the theorem pertains, not to satisfiability I think, but validity. Nortexoid (talk) 21:16, 4 May 2008 (UTC)


 * Yes, the article is misleading. I'd like to fix it, but I don't know what it's trying to say. I'm just going to remove that sentence for now, we can always add it later if we figure out how to correct it. &mdash; Carl (CBM · talk) 21:17, 4 May 2008 (UTC)

"Strong" Completeness Theorem
In the fourth paragraph: "Truth-value semantics is not without its problems. First, the strong completeness theorem and compactness fail" -- can someone give us a pointer as to what the strong completeness theorem is? It doesn't seem to be mentioned in Gödel's_completeness_theorem (that I could find). Thanks BrideOfKripkenstein (talk) 15:44, 5 October 2010 (UTC)

Reference needed
The article mentions Dunn and Belnap 1968, which is what? 86.185.216.86 (talk) 23:22, 9 January 2014 (UTC)