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Two questions about bagid

From: Tim Berners-Lee <timbl@w3.org>
Date: Tue, 11 Feb 2003 14:15:16 -0800
Cc: www-rdf-comments@w3.org
To: RDF Core <w3c-rdfcore-wg@w3.org>
Message-Id: <4C854F09-3E0E-11D7-84BF-000393914268@w3.org>

I have a question about implementation of the bagid feature.
My parser doesn't currently implement it, and so  fails the RDF
tests which involve it.   The same seems to apply to Ids on
arcs.

One curious thing is that I have not yet found a live case which
which uses bagid to produce the reification suggested in the spec.
No one on the #RDFIG channel when the question
was posed yesterday could could really think of an application
which used it, and no one could really defend its existence as a 
feature.
I couldn't by a Google search find any real use on the web.
(apart from papers about RDF and test cases).
Is this feature then worth implementing? What does the group think?


Another question is about the semantics.
I understand that an id  :i  on the statement  { :superman :can :fly}
should generate the statements

:i a rdf:Statement;  rdf:subject :superman;   rdf:predicate :can; 
rdf:object :fly.
:superman :can :fly.

and I might want to use this to generate attribution:

:lois :thinks :i.

This would suggest that an owl reasoner (say) that knows that :superman 
and
:clarkekent are daml:equivalent should be able to infer that

:i a rdf:Statement;  rdf:subject : clarkekent;   rdf:predicate :can; 
rdf:object :fly.
: clarkekent :can :fly.
:lois :thinks :i.

This seems counterintuitive, as one would expect it allow one to 
conclude
that the modified statement is due to the original source.
Some form of quoting around the subject, predicate
and object would seem necessary.

I have been guilty of ignoring this rather complicated bit of the spec,
and wonder whether others have done the same.

A developer.
Received on Tuesday, 11 February 2003 17:14:36 EST

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