Re: A question for Mr. Celko
Date: Mon, 19 Jul 2004 22:56:36 GMT
Message-Id: <pan.2004.07.19.22.57.16.709896_at_REMOVETHIS.pandora.be>
On Mon, 19 Jul 2004 11:13:53 -0700, John Jacob wrote:
>
> In fact, *any* formal system at least as powerful as typographical
> number theory (which a relational language certainly is, even without
> relation-valued attributes) is subject to the Godelian attack, it says
> *nothing whatsoever* about whether or not the system is useful.
Not so fast. The relational algebra corresponds to first-order logic without function symbols, which is a strict subset of FOL with function symbols, and for that Godel is actually our friend because he has shown that we have a complete axiomatization for that, known as Godels completeness theorem. Which, by the way, doesn't mean things get suddenly easy because FOL, even without function symbols, is still undecidable.
- Jan Hidders