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Troublesome relations

From: Danny Ayers <danny.ayers@gmail.com>
Date: Tue, 19 Oct 2004 13:34:38 +0200
Message-ID: <1f2ed5cd041019043435c0dbab@mail.gmail.com>
To: www-rdf-interest@w3.org
Cc: jay@icite.net

I've recently been reading around crossover between the RDF model and
Codd's relational database model. Jay Fienberg brought to my attention
[1] to a couple of comments from C. J. Date and F. Pascal (the
legendary database debunkers): On Metadata, RDF and Relational
Representation [2] and On Relational Binary Database Design [3]. Their
line in both is essentially that the RDB is the One True Model. The
comments in [3] don't seem unreasonable (however debatable), but [2]
is a longish query with a terse response from Date:

This approach is the old argument that all relvars should be binary in
a different guise! Thus, a cogent counterargument is:  How do you deal
with irreducible n-order predicates for n <> 2?

Problem I'm having is coming up with practical examples of such
predicates, or how this might impact on RDF modelling. (I could well
be misinterpreting Date's statement, as Googling "all relvars should
be binary" doesn't exactly give evidence of an old argument, rather it
gives [2] as the first hit and expanding to 'relation variables'
didn't help any).

The nearest I can get is in wondering perhaps if this is isomorphic
with the way RDF predicates can't be treated as instances for
per-usage qualification, you can't really go from predPQ(a, b, c) to
predP(a, b), predQ(predP, c).

/notation undoubtedly dodgy, hope you can read my mind/

Can anyone please shed light?


[1] http://icite.net/blog/200410/data_articles.html
[2] http://www.dbdebunk.com/page/page/1114998.htm
[3] http://www.dbdebunk.com/page/page/1147347.htm


Received on Tuesday, 19 October 2004 11:34:39 UTC

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