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RE: [TF-ENT] A few comments on RDFS Entailment section

From: Seaborne, Andy <andy.seaborne@hp.com>
Date: Tue, 6 Oct 2009 10:59:50 +0000
To: Birte Glimm <birte.glimm@comlab.ox.ac.uk>
CC: SPARQL WG <public-rdf-dawg@w3.org>
Message-ID: <B6CF1054FDC8B845BF93A6645D19BEA3693ECF7193@GVW1118EXC.americas.hpqcorp.net>
More general enquiry:  (this is something that came up in the last WG and my recollection may be partial so forgive an ignorant question):

Suppose 

  G    is  _:x :p :z , 

  SG   is  _:a :p _:b

  BGP  is   ?x :p [] .

Does that mean there are two solutions 

?x = _:a
?x = _:b

Because

P(BGP) are well-formed RDF triples that are RDFS entailed by G
(C1) each subject is in the set of terms used by the scoping graph 
(C2) μ(?x) is a blank node occurring in SG.

What I'm not clear about is that C1 and C2 only talk about the use in SG so is symmetric in _:a and _:b.  I see no asymmetry to produce one solution over another as it's not the use in triples in SG.  Any SG with more than one bNode will generate alternatives, increasing with the number of bNodes.

Under simple entailment matching there is one because "P(BGP) is a subgraph of G" and not an entailment relationship, and ?x=_:x.  (DAWG did try for an entailment relationship but the cardinality issues were a problem.)
 
	Andy

Received on Tuesday, 6 October 2009 11:01:40 GMT

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