Re: Principle of Orthogonal Design

From: David Cressey <>
Date: Mon, 21 Jan 2008 15:09:16 GMT
Message-ID: <wA2lj.4389$YH6.1499_at_trndny03>

"Brian Selzer" <> wrote in message news:kO1lj.2507$

> I think that there are times when it makes sense to 'collectivize' under a
> single predicate, and there are times when it does not. In particular, if
> the individuals represented are just different kinds of the same sort of
> thing, such as is the case with the different kinds of phone numbers, then
> it makes sense to 'collectivize' those attributes that are common to all
> those individuals under a single predicate. If, on the other hand, the
> individuals represented are different sorts of things that just happen to
> have the same attributes, then it doesn't. A disjunctive
> predicate--something like, for example, each tuple exemplifies an
> that is an X or a Y, just doesn't make any sense to me. A conjunctive
> predicate on the other hand--for a relation that has multiple keys, for
> example--is not a problem since each tuple would exemplify an individual
> that is /both/ an X /and/ a Y. So if the predicate can be stated so that
> is not disjunctive, then 'collectivizing' is to be preferred.
It seems to me that you are describing the generalization-specialization pattern.
Am I reading you right?

> > Either way, I certainly find that appealing to notions of "meaning"
> > within formal design recommendations seems to head towards very
> > slippery ground.
> >

Why? If you called it "the semantics of the data" instead, would that make it less slippery ground? Received on Mon Jan 21 2008 - 16:09:16 CET

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