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Queries returning only constants

From: Sandro Hawke <sandro@w3.org>
Date: Tue, 23 Oct 2001 17:55:06 -0400
Message-Id: <200110232155.f9NLt6823914@wadimousa.hawke.org>
To: joint-commitee@daml.org
Cc: www-archive@w3.org

It seemed to me there was a real disagreement at the end of the
joint-committee call today.  Here's a test case.  If I understood
correctly, Pat (and I) will vote for (b) and Richard will vote for

The knowledge base contains the statements: "Pat's car is blue, and
there is something colored red."  Somewhat more formally:

  RDF(PatsCar, color, blue).
  exists x (RDF(x, color, red)).

or in N-Triples (ignorng URI syntax)

 <patsCar> <color> <blue>.
 _:a <color> <red>.

And then we have the query: "is there anything with any color?", or
RDF(?x, color, ?y). 

Do we get back

(a) 1 triple

 <patsCar> <color> <blue>.

or (b) 2 triples

 <patsCar> <color> <blue>.
 _:b <color> <red>.

(where I've changed the _:a to _:b just to emphasise that it is an
arbitrary term, and its scope does not carry over from the knowledge
base to the response).

or (c) 2 triples with genid (skolem constant)

 <patsCar> <color> <blue>.
 <reasonerCreatedSymbol79878687> <color> <red>.
If everyone actually is happy with (b), then we were in fact in
violent agreement.  If not, then there's a real issue here. 

      -- sandro       http://www.w3.org/People/Sandro/
Received on Tuesday, 23 October 2001 17:58:41 UTC

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