Re: Guessing?

From: Brian Selzer <>
Date: Tue, 27 May 2008 16:16:52 -0400
Message-ID: <Y_Z_j.2512$>

"paul c" <toledobysea_at_ac.ooyah> wrote in message news:13V_j.168060$rd2.163010_at_pd7urf3no...
> Brian Selzer wrote:
> ...
>> In TTM, Darwin raises objections to such a strict form of orthogonality,
>> and I agree: it's a problem to disallow more than one relationship
>> between things, and in the case of unary relations, it's a problem to
>> disallow something from having more than one property. (Page 436 if
>> you're interested.)
>> ...
> Anything Hugh DarwEn says is likely to be important or at least
> provocative, but how does POOD disallow multiple relationships or
> properties?

Here's a snippit from page 436, /Databases, Types and the Relational Model, The Third Manifesto/:


    As applied to 1-tuples, the strong form of orthogonality is effectively saying that the database should not permit the same thing to have more than one "property" (a term used by some logicians to characterize monadic predicates). Consider, for example, the predicates "Employee E is on vacation" and "Employee E is awaiting phone number allocation." What more natural way is there of representing those than defining two unary relvars with those very predicates?

Received on Tue May 27 2008 - 22:16:52 CEST

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