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Re: Thinking out lout about some strange SPARQL entailment test cases...

From: Polleres, Axel <axel.polleres@deri.org>
Date: Fri, 27 Aug 2010 20:13:21 +0100
Message-ID: <316ADBDBFE4F4D4AA4FEEF7496ECAEF9035DF82B@EVS1.ac.nuigalway.ie>
To: <birte.glimm@comlab.ox.ac.uk>
Cc: <public-rdf-dawg@w3.org>
Yes, the second one was meant as D-entailment test case, and I expected both not to return any result.

Axel

----- Original Message -----
From: b.glimm@googlemail.com <b.glimm@googlemail.com>
To: Polleres, Axel
Cc: SPARQL Working Group <public-rdf-dawg@w3.org>
Sent: Fri Aug 27 20:11:39 2010
Subject: Re: Thinking out lout about some strange SPARQL entailment test cases...

Sorry, I didn't comment on the second test case

> Similarly:
>
>  G:
>   :s :p 1
>
>  Q:
>  SELECT ?L
>  WHERE { ?L a xsd:integer }

I think that would need datatype awareness and RDFS does not support
the XSD schema datatypes (you would need D-Entailment or higher). Even
if we have
:s :p "1"^^xsd:integer.
a system unaware of xsd datatypes might read that triples, but it will
not necessarily infer
"1"^^xsd:integer a xsd:integer .
or even
"1"^^xsd:integer a xsd:short .
which is also true I guess. At least for OWL reasoners what counts
internally is the denoted data value and "1"xsd:short and
"1"xsd:integer is the same data vale with different lexical forms. Now
for OWL Direct Semantics that BGP is not legal, so your only hope
would be OWL with RDF-Based Semantics or some D-Entailment
implementation.

Now, even with XSD awareness and not counting it as illegal RDF, the
answers would not be infinite because you only consider the data
values in the graph.

Birte

>
> Obviously, those will not give an answer, but some people might expect those to return surrogate blank nodes... a colleague of mine just came to me with that (in a different context), and I thought I might share it.
>
> Axel



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Received on Friday, 27 August 2010 19:13:58 GMT

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