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Re: Does the expressive power of SPARQL include all forms of default negation?

From: Danny Ayers <danny.ayers@gmail.com>
Date: Wed, 2 Sep 2009 13:12:59 +0200
Message-ID: <1f2ed5cd0909020412sb532c33v4bd1a2390b82ee0@mail.gmail.com>
To: "Seaborne, Andy" <andy.seaborne@hp.com>
Cc: Lee Feigenbaum <lee@thefigtrees.net>, Chimezie Ogbuji <ogbujic@ccf.org>, "public-sparql-dev@w3.org" <public-sparql-dev@w3.org> 
2009/9/2 Seaborne, Andy <andy.seaborne@hp.com>:

>> Chimezie Ogbuji wrote:

>> > Basically, the problem is one where I want to find "all resources that
>> are
>> > not a member of a specific class".  This seems to be especially
>> problematic
>> > for RDF graphs where each resource has *multiple* rdf:type statements.
>> > Consider the graph:
>> >
>> > _:b rdf:type D
>> > _:a rdf:type C
>> > _:a rdf:type D
>> > _:a rdf:type B
>> >
>> > And we want to find "all resources that are not a member of the C
>> class,"
>> > where the *not* in this case is meant in the closed world sense (i.e.,
>> > basically there is no statement of the form:  ?RESOURCE a C in the
>> graph).

Excuse me folks, but I'm not quite grasping something here - would NOT
EXISTS/UNSAID be introducing something new, or would it be sugar for
the kind of convoluted !BOUND query Chime described?

Cheers,
Danny.

-- 
http://danny.ayers.name
Received on Wednesday, 2 September 2009 11:13:45 GMT

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