Re: Database design, Keys and some other things

Gene Wirchenko wrote:
> >P = { <feature: sky>, <colour: blue>, <period: daytime> }
>
> >The extra information I specified in the previous post however, is
> >absolutely not part of this statement about the world. Rather it is
>
> Of course it is. If nothing else, it is bibliographic, but I
> would restructure the statement to:
> [Gene's P =] James says that [James's] P.

If you are saying there is a distinction between the observer of the proposition and the creator of the tuple, just as there is a distinction between the time of the observation and the time of the tuples creation in the db, well, yes I agree. This was the intention of the example, although it may have become obfuscated along the way. But there is a distinction, and if Gene were the person who observed the the fact that the sky is blue in the day, we have:

P = { <feature: sky>, <colour: blue>, <period: day>, <observer: Gene>}

M = { <creator: James>, <created: 1127871055>, <statement: P> }

P is just a finite partial mapping, and as such my (granted often unreliable) spider-sense is still telling me that like any function, there may exist relationships that do not belong as part of P's extensional representation (orderings, set membership, etc). Easy employment and manipulation of these would utilise an implicit conceptual reference (as I would use the letter P in the mathematical notation - but instead I have to hack in and manage an explicit artificial key, or specify "on update cascade"s all over the shop to maintain integrity.)

On a side note, it has of course been pissing it down in the UK, and the sky is absolutely, categorically and unequivicably, not blue :) Received on Wed Sep 28 2005 - 23:29:33 CEST