W3C home > Mailing lists > Public > www-rdf-interest@w3.org > December 2003

Re: Trust, Context, Justification and Quintuples

From: Sandro Hawke <sandro@w3.org>
Date: Thu, 18 Dec 2003 19:36:32 -0500
Message-Id: <200312190036.hBJ0aXJK014661@roke.hawke.org>
To: "Thomas B. Passin" <tpassin@comcast.net>
Cc: www-rdf-interest@w3.org


> > Why not just reify the statement?
> 
> Well, of course one can do that.  But the reason people keep coming up 
> with suggestions to have a quad or a statement identifier instead of 
> using reification has, I think, to do with weaknesses in RDF 
> reification.  There are several issues that I know about -
> 
> 1) It is complex - you end up with four triples where all you want to do 
> is to reference a statement.

Three, not four, I think.  The domain of rdf:subject is rdf:Statement,
so the rdf:Statement triple need never be said.

> 2) The interpretation of a reified statement is not well defined.  For 
> example, it is NOT a representation for any actual triple in the data 
> store, and it is NOT considered "asserted"... So what is a reified 
> statement and how should it relate to the other triples?

Indeed, it would be nice to have a truth predicate to match the
reification bits.   Let's define one.  :-)

> 3) It is contorted -  if a statement had its own resource identifier, it 
> would be easy and natural to refer to it as the object of an RDF 
> statement.  And, of course, practical RDF processing systems are likely 
> to have some internal identifier, so why to make one externally available?

Of course any RDF/XML file on the web gives you a URI for the
conjunction of zero or more RDF triples.   That's not far from what
folks often want, even if the granularity doesn't always match
people's expectations.

       -- sandro
Received on Thursday, 18 December 2003 19:36:05 GMT

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