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thinking about the formal model for RDF

From: Stefan Kokkelink <skokkeli@mathematik.uni-osnabrueck.de>
Date: Thu, 12 Jul 2001 14:28:42 +0200
Message-ID: <3B4D97FA.118885B7@mathematik.uni-osnabrueck.de>
To: RDF interest group <www-rdf-interest@w3.org>
1. (see last mail) Anonymous Resources are part 
of the RDF model.

Why? The spec often talks about anonymous resources, for example
Figure 2 "The sentence above does not give a name to the resource;
it is anonymous, so in the digram below we represent it with an empty
oval" You may also have a look at Brian's analysis in 2.2 Anonymous
Resources http://www-uk.hpl.hp.com/people/bwm/papers/20001221-paper/

That means: If Resources are named, they are named by URIs, else
they are anonymous.

Now have a look at 5. Formal Model for RDF. 
- There is a set called Resources
- There is a set called Literals
- There is a subset of Resources called Properties 
- There is a set of Statemnts,, each Statement is a
  triple {pred,sub,obj} where ...
- ...

There is no problem with anonymous resources here. It 
is not said in sec 5 that a resource *must* be 
named by a URI! Sec 5 just talks about the *set* of
resources. Sec 5 does not talk about a syntactic representation
of triples that, for example, a parser may *choose* to 
represent the formal model.

2. An isolated node can be presented in the formal model 
for RDF.

Why? Well, the formal RDF model consists of many sets:
the set of Resources, Literals, ... It is not said that
the formal Model is (only) given by a set of triples! The formal
model consists of a set of Resources AND a set of Literals
AND a set of Statements AND ... In Sec 5 there are two examples
given how one could *represent* a Statement of the formal Model:as
graph (Figure 12) and as a triple. 

Regarding 1) this means: If you choose a syntactic triple representation
for a Statement that has an anonymous resources as subject or object,
you have to invent an *internal* identifier (relative to the chosen
syntactic representation). But that does not mean that the anonymous
resource suddenly has a name! It is still anonymous.

Just some thoughts ;-)

Received on Thursday, 12 July 2001 08:30:20 UTC

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