Re: Constraints and Functional Dependencies
Date: Sun, 25 Feb 2007 14:07:17 +0100
> mAsterdam wrote:
>> But what exactly is the reference referencing? >> A set of S-tuples, not just one. >> That makes it a sort of hand_wave instead of a reference, right? >> >> Is there something I am missing?
> Maybe the preeminence of RA domain associative characterization over
> structuralist perspective based on attributes.
I need some help to decipher this.
>> <handwave> >> (i a) >> A relation R with attribute a (written as R(a)) having >> a as a handwave into S(b) >> is expressed as follows: >> >> forall R(a): exists S(b): a = b >> >> Note that b need not be a ck to S, hence 'into', not 'to'. >> </handwave>
> Again, attribute-based characterization of domains and relations leads
> to a conceptual dead end and a circular argumentation about key (As
> you can see).
I really don't know if I am reading this right.
I don't see circularity in Marshall's FD/ck expression. Do you?
> Pulling out of it requires effort. It seems however
> that this perspective and the proof of it ellludes some of the
> audiences. I do not know how to express it better than I did.
Received on Sun Feb 25 2007 - 14:07:17 CET