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Statements/Reified statements

From: Pierre-Antoine CHAMPIN <champin@bat710.univ-lyon1.fr>
Date: Wed, 22 Nov 2000 14:21:25 +0100
Message-ID: <3A1BC855.94B94590@bat710.univ-lyon1.fr>
To: ML RDF-interest <www-rdf-interest@w3c.org>
Well; I feel like starting a new thread about unicity of triples,
my mailer windows is no longer wide enough :)

The more I read the messages on the list and the specs,
the more I think there is a possible unification of all our views;
I'll try to sum it up, being consistent with the spec.

First, Statements and Reified statements are not the same thing.

Statements are uniquely defined by their subject/predicate/object. The spec says so (section 5, item 4). They are therefore what we sometimes called "abstract statement". The spec does *not* say that they are resources.

Reified statements are resources, defined in section 5, item 9. They *represent* a statement -- it sounds therefore fair that a statement may have more than one representation. They also have the 4 well know properties, now often called the "reification quad".

We also defined a "stating" as the *expression* of a statement in some piece of RDF (i.e. an arc in the graph, a triple occurence in a model). It is clear that there can be more than one stating for the same statement (although there may be only one per graph/model).

About resources, RFC2396 says:

         The resource is the conceptual mapping to an entity or set of
         entities, not necessarily the entity which corresponds to that
         mapping at any particular instance in time.

The question is: does a reified statement map to the statement (a) or the stating (b) , or both, depending on the context (c) ? I do not think the specs answer this question, so any interpretation is allowed.

If we all agree about that, then we have to consider advantages and drawbacks of each three options, and have it put down in a W3 note once for all.

  Pierre-Antoine  -- suggesting (c), but waiting other's opinions ;-)

Sometimes I think the surest sign that intelligent life exists elsewhere in the
universe is that none of it has tried to contact us.
(Bill Watterson -- Calvin & Hobbes)
Received on Wednesday, 22 November 2000 08:22:00 UTC

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