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Re: LC Comment: Restriction on Solutions for RDF-Based Entailment Regime

From: Birte Glimm <birte.glimm@uni-ulm.de>
Date: Thu, 10 Nov 2011 10:17:49 +0100
Message-ID: <CABt65Ofso6gQQdymrmO=jEKq3OFL4KxbesNptQXf3JOkNncY+g@mail.gmail.com>
To: Michael Schneider <schneid@fzi.de>
Cc: public-rdf-dawg-comments@w3.org
Michael,

Thank you for your comment and the clarification about the editorial
comment regarding infiniteness due to datatype reasoning under OWL's
RDF-Based Semantics.

The current editor's draft no longer contains the editorial note and
includes an even simpler example that already illustrates the point.

The current editor's draft is available at:
http://www.w3.org/2009/sparql/docs/entailment/xmlspec.xml

We would be grateful if you would acknowledge that your comment has
been answered by sending a reply to this mailing list.

Birte, on behalf of the SPARQL-WG

On 30 July 2011 19:36, Michael Schneider <schneid@fzi.de> wrote:
> Dear all!
>
> The SPARQL 1.1 Entailment Regimes LCWD, Section 5.2 "Restriction on
> Solutions" in the Chapter defining the OWL 2 RDF-Based Entailment Regime,
> contains an example query consisting of several complex class expressions
> and an Editorial Note, which states
>
>    It could be the case that this example only applies to the
>    OWL 2 Direct Semantics and that for the RDF-Based Semantics
>    one would have to introduce axioms that force a domain
>    element to exist for each extension of the class expressions
>    ...
>
> This is correct.
>
> There is, however, an alternative kind of query, which would be close in the
> spirit of the current query, but without suffering from the problem of the
> RDF-Based Semantics that one needs the existence of individuals representing
> class or property extensions:
> One can use a query based on a /negative data property assertions/, for
> example in the following form:
>
>    SELECT ?x WHERE {
>        _:z rdf:type owl:NegativePropertyAssertion ;
>        _:z owl:sourceIndividual ex:peter ;
>        _:z owl:assertionProperty ex:dp ;
>        _:z owl:targetValue ?x .
>    }
>
> The expected possible results of this query would, as for the current query,
> be all literals L to which ex:peter does /not/ have a ex:dp-relationship,
> e.g. L := "6"^^xsd:integer and so on, so the result set would be infinite,
> if not restricted.
>
> There is a specific RDF-based semantic condition that ensures the existence
> of such a "_:z" that combines the triples in the multi-triple representation
> of negative property assertions:
>
>
> <http://www.w3.org/TR/2009/REC-owl2-rdf-based-semantics-20091027/#item-semcond-negassert-data-bw>
>
> Best regards,
> Michael
>
> --
> Dipl.-Inform. Michael Schneider
> Research Scientist, Information Process Engineering (IPE)
> Tel  : +49-721-9654-726
> Fax  : +49-721-9654-727
> Email: michael.schneider@fzi.de
> WWW  : http://www.fzi.de/michael.schneider
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> Studer
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> ==============================================================================
>
>



-- 
Jun. Prof. Dr. Birte Glimm            Tel.:    +49 731 50 24125
Inst. of Artificial Intelligence         Secr:  +49 731 50 24258
University of Ulm                         Fax:   +49 731 50 24188
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Germany
Received on Thursday, 10 November 2011 09:18:32 GMT

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