Re: Principle of Orthogonal Design

From: JOG <jog_at_cs.nott.ac.uk>
Date: Tue, 5 Feb 2008 04:58:01 -0800 (PST)
Message-ID: <5612d17a-fa44-4e22-bfd8-6e444ac3cfda_at_d70g2000hsb.googlegroups.com>


On Feb 5, 12:55 pm, thesabote..._at_gmail.com wrote:
> On Feb 3, 1:02 pm, Jan Hidders <hidd..._at_gmail.com> wrote:
>
> > On 2 feb, 13:50, mAsterdam <mAster..._at_vrijdag.org> wrote:
> > [huge snips]
> > > I think 'named perspective' was just an unfamiliar
> > > label to a familiar concept.
>
> > Yes. The named perspective is the usual perspective where tuples are
> > defined as functions from attribute names to domain values, and the
> > unnamed perspective is where they are defined as sequences. The latter
> > is sometimes preferred in theoretical work because it is closer to how
> > logicians formalize things (in P(x,y,z) there are no attribute names,
> > just the 1st, 2nd and 3rd place in the predicate) and it simplifies
> > notation sometimes.
>
> I would echo that this is an important distinction to be aware of. I
> personally favour the named perspective for a couple of reasons:
> first, when Codd introduced attribute names there was an implicit
> shift from a traditional ordered mathematical tuple, to a "tuple"
> being viewed as an (unordered) partial function. Second, without the
> attribute name a datum is in fact no datum at all, but rather simply
> noise. Attributes are as much a component of the data under
> consideration as the value they are mapped to. Hence, to disregard (or
> rather externalize) attributes from a mathematical model of data seems
> rather imprudent.

Well I haven't done that for a while. Must. Log. In. Received on Tue Feb 05 2008 - 13:58:01 CET

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