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some initial comments on SPARQL Query Language for RDF revision 1.596 of 19 December 2005

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Wed, 21 Dec 2005 09:23:29 -0500 (EST)
Message-Id: <20051221.092329.110028704.pfps@research.bell-labs.com>
To: public-rdf-dawg-comments@w3.org

[Jumping the gun a little bit.]

I just read over the first few sections of SPARQL Query Language for RDF
revision 1.596 of 19 December 2005, and I have a few concerns:

0/ I am disappointed that this is all that can be obtained from DAWG.
Nevertheless this document is much better than the previous one.

1/ This appears to be quite a change.  Will there be some description of what
the change amounts to?

2/ The definitions put much more of a burden on the RDF graph-generating
process.  I think that this needs to be addressed much more fully.  In
particular, I think that it would be useful to explain that some systems store
a particular RDF graph that is not related to an input RDF graph by any
relationship sanctioned by the RDF recommendations.  Directly querying such RDF
graphs could result in pecular answers. As well, I think that it would be
useful to indicate that if querying results approximating RDF entailment or
RDFS entailment are desired, then the RDF graph that is being queried will be,
of ncecessity, not explicitly stored anywhere.

3/ I think that it would be useful to indicate that the only purpose of the wording
"whose range is a subset of the set of RDF terms occuring in G" is to prevent
having an infinite number of answers.  I don't think that it eliminates
"redundancy" in answers, as I believe that the query 
	?a r ?b .
against the graph 
	_:a r _:b .
will have two answers.

4/ I don't see why Section 2.9 is included.  I believe that it changes
nothing.  I believe that it only serves to provide the illusion that there is
something special about RDF reification.

5/ I don't understand why Section 3.1.4 is included.  Yes, producing an RDF
graph that is the D-entailment closure of another RDF graph can lead to
additional matches, but this is the case for any augmentation process.  Why
then signal out D-entailment in this way?  It only serves to provide the
illusion that there is something special going on.

6/ I believe that Section 3.4 is not correct and needs to be removed from the
document.  

Probably more later,

peter
Received on Wednesday, 21 December 2005 14:23:47 GMT

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