W3C home > Mailing lists > Public > public-rdf-dawg@w3.org > July to September 2010

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

From: Axel Polleres <axel.polleres@deri.org>
Date: Sat, 28 Aug 2010 10:08:16 +0100
Cc: <public-rdf-dawg@w3.org>
Message-Id: <A2712C82-CDB5-4F6A-A914-6C64C18AEFD5@deri.org>
To: "Birte Glimm" <birte.glimm@comlab.ox.ac.uk>

On 27 Aug 2010, at 23:32, Birte Glimm wrote:

> On 27 August 2010 20:13, Polleres, Axel <axel.polleres@deri.org> wrote:
> > Yes, the second one was meant as D-entailment test case, and I expected both not to return any result.
> 
> Because it is not well-formed RDF or because you think it is not entailed?

What would be entailed was

_:SURROGATE_BNODE_FOR_1 a xsd:integer

cf. entailment rule rdfD1 (Section 7.4) in the informative entailment rules of rdf-mt [1].
but at the moment we don't bother about "surrogate" bnodes for literals, but only return 
terms appearing in the orignal graph. (similarly for the RDFS example) I only meant those test cases for making that clear to users/implementers: That is, if I implement RDFS/D entailment by implementing the informative entailment rules, I get results which are not mandated by our current definitions of RDFS/D entailment in SPARQL.

Hope that the intention is clearer now,
Axel
 

1. http://www.w3.org/TR/rdf-mt/

> Birte
> 
> > 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
> >
> >
> >
> > --
> > Dr. Birte Glimm, Room 309
> > Computing Laboratory
> > Parks Road
> > Oxford
> > OX1 3QD
> > United Kingdom
> > +44 (0)1865 283520
> >
> 
> 
> 
> --
> Dr. Birte Glimm, Room 309
> Computing Laboratory
> Parks Road
> Oxford
> OX1 3QD
> United Kingdom
> +44 (0)1865 283520
> 
Received on Saturday, 28 August 2010 09:08:55 GMT

This archive was generated by hypermail 2.3.1 : Tuesday, 26 March 2013 16:15:43 GMT