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Re: RDF-ISSUE-25 (Deprecate Reification): Should we deprecate (RDF 2004) reification? [Cleanup tasks]

From: William Waites <ww@styx.org>
Date: Sat, 9 Apr 2011 12:06:19 +0200
To: Ivan Herman <ivan@w3.org>
Cc: Sandro Hawke <sandro@w3.org>, Richard Cyganiak <richard@cyganiak.de>, Eric Prud'hommeaux <eric@w3.org>, David Wood <dpw@talis.com>, RDF Working Group WG <public-rdf-wg@w3.org>
Message-ID: <20110409100619.GC85740@styx.org>
* [2011-04-09 11:51:11 +0200] Ivan Herman <ivan@w3.org> écrit:

] I must admit I do not understand what this has to do with 
] reification. Yes, the model you describe is fairly common
] and, to take an even more widely used example, it is the
] same pattern as the one used for a foaf:Person.
] 
] I seem to miss something here.

The difference being that a foaf:Person is a thing in some sense, and
an org:Membership really wants to be a relationship. And relationships
are meant to be expressed as predicates except that we can't do that
here because it wants four arguments instead of two. What would be the
natural way to write down a foaf:Person in prolog? What would be the
natural way to write that this person is a certain type of member of
something?

Or to put it another way it might have been possible for the authors
of org to do the same thing by making a memberOf predicate and then
using sub-predicates to refine the idea. There might be many such
sub-predicates as they would be parametrised by time periods. This is
kind of like curried predicates if you will. Even though it might be
more natural to think of things this way, predicate explosion, the
fact that some stores do not like enormous amounts of ad-hoc
predicates, and the general lack of subproperty reasoning would make
this way actually worse than the reification they use.

Does that make more sense?

-w
-- 
William Waites                <mailto:ww@styx.org>
http://river.styx.org/ww/        <sip:ww@styx.org>
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Received on Saturday, 9 April 2011 10:06:44 GMT

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