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From: Seth Russell <seth@robustai.net>
Date: Thu, 24 Jan 2002 14:26:21 -0800
Message-ID: <001301c1a526$27089a20$657ba8c0@c1457248a.sttls1.wa.home.com>
To: "RDF-LOGIC" <www-rdf-logic@w3.org>
Cc: "Pat Hayes" <phayes@ai.uwf.edu>
At http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2002Jan/0257.html
Pat Hayes said:

The trouble with this kind of approach (not to reification in
particular, but more generally) is that if there is no way in the
language to state a distinction, and if the same constructs are used
to say different kinds of things, then confusion will be inevitable.
Maybe some people will manage to get by, but someone else will be
confused (or, worse, some other piece of software will get confused.)
Surely it is better to provide a way to state or somehow indicate the
distinction [*1], and allow both kinds of things to be said more clearly.
If you want strict backward compatibility and don't like new
syntactic conventions, then make the one you like best be the
unmarked case and mark the other one.
... ]]

Would you agree that whatever a reification node is, it is certainly is a
blank node?

_:s1 rdf:type rdf:Statement
_:s1 rdf:predicate :pred
_:s1 rdf:subject    :sub
_:s1 rdf:object     :obj

Doesn't the MT say that a blank node simply indicates "the existence of a
thing".  So the Ntriples above just say:

(exists (?x)
          (rdf:type ?x  rdf:Statement)
          (rdf:predicate ?x :pred)
          (rdf:subject ?x :subject)
          (rdf:object ?x :obj)

So our interpretation is any of the things which qualify according to the
above formula that exist in our universe.  If we want to further qualify
those things to statings in a particular document, then we could add further
restraints to the formula like:

(exists (?x)
          (rdf:type ?x  rdf:Statement)
          (rdf:predicate ?x :pred)
          (rdf:subject ?x :subject)
          (rdf:object ?x :obj)
          (dc:auther ?x :Seth)
          (dc:document ?x "http://foo/bar.rdf" )

My question is:  Does considering reified statements to be the blank nodes
("existential assertions") means that we can draw whatever distinctions your
refer to above [*1] with additional Ntriples on the same blank node
identifier ... and that it is not necessary for the MT to further refine the
definition ... but rather allow the user to draw those distinctions with
additional triples?

(no mentograph necessary)
Seth Russell
Received on Thursday, 24 January 2002 17:29:26 UTC

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