Re: Logical = relational?
Date: 4 May 2006 14:54:19 -0700
Message-ID: <1146779659.465800.139550_at_v46g2000cwv.googlegroups.com>
Nice post, but I still would like to add a few remarks.
Mikito Harakiri wrote:
>
> The next natural step is to move into the field of n-ary relations. The
> first attempt was made by Tarski with introduction of cylindric
> algebras.
That sounds a bit odd to me. Since Frege around 1880 basically invented first order predicate logic the step to n-ary relations already had been made. It seems that your overview is somewhat biased towards algebraization of logic, which is an important aspect, but certainly not the only important aspect. What about Wittgenstein (proof by truth tables), Goedel (completeness and incompleteness theorems), Herbrand (Herbrand universe), Robinson (resolution for FOL)? What about finite model theory? All these are probably much more important from a database theory perspective.
> The relation dimension moved from 2 to n, but remained fixed.
> E Codd expanded the idea to manipulate relations of mixed dimensions.
Mixed dimensions? I have no idea what that means. Codd also talked about n-ary relations so I don't see what in what sense the idea was expanded except that perhaps the places in the predicates now became labled with names.
- Jan Hidders