Re: teaching relational basics to people, questions

From: <compdb_at_hotmail.com>
Date: Thu, 19 Nov 2009 18:56:25 -0800 (PST)
Message-ID: <dc0c846d-d902-4271-8d78-01c935d6e169_at_x25g2000prf.googlegroups.com>


On Nov 19, 1:32 am, Sampo Syreeni <de..._at_iki.fi> wrote:

> As I see it, the condition that there be at
> most one non-prime attribute is a constraint on the relation in the
> usual sense.

> > (thus, meaningless) phrases like "logically subsumed".
> At least that one has a perfectly standard meaning in mathematics.
> It's strictly the same as "is implied by".

If you look into it you might find differently.

Regardless (or perhaps, with regard to those "other ones"), it has been my experience that phrases like "As I see it" are rhetorical wafflings. As if, when later shown wrong, you can say, ok, that might not be the way it is, but that's the way I saw it, and all I claimed was that I saw it that way, and I did, so I wasn't wrong.
I am not trying to catch you at anything. I'm trying to help (about normal forms and your writing, both). (And because of the exercise in improving my reasoning, understanding and writing.)
As I said, it helps to force oneself to be direct and precise, because it (painfully) makes one think and write more clearly.

Regarding constraints & you vs Date we remain in disagreement. Hope someone else can help.

philip Received on Fri Nov 20 2009 - 03:56:25 CET

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