- From: Birte Glimm <birte.glimm@comlab.ox.ac.uk>
- Date: Fri, 19 Mar 2010 12:49:25 +0100
- To: SPARQL Working Group <public-rdf-dawg@w3.org>
Hi all, I updated several parts of the doc. I added D-entailment (just following the same line as the others), I describe the mapping from triples to OWL objects more precisely (Matthew Horridge suggested to have a grammar and I now outline how we extend the grammar from the OWL 2 structural spec by allowing for variables and how the OWL mapping from RDF graphs to OWL objects can be extended to work with variables). This means that we now have a clear definition of well-formed queries for the Direct Semantics regime and several of the conditions are now obsolete since the grammar captures this. OWL Direct Semantics is also much closer to the other regimes now. As long as you have well-formed graphs and BGPs, basically the same C1 and C2 apply (just the scoping graph SG becomes the ontology O(SG) obtained from SG). In addition to the standard C1 and C2 we also have C3, which requires that adding the instantiated triples to O(SG) still gives an OWL 2 DL ontology. This prevents, for example, that I instantiate an object property variables in a cardinality constraint with a non-simple role. This would make reasoning undecidable and cannot be captured by a grammar, but is defined in the OWL 2 DL constraints. This is now all that is required for Direct Semantics, so the regime is much better in line with the others. There is an optional condition C4, which can be used to make datatype reasoning feasible (for the general case we are not yet sure how to do that in all cases). Since this is optional, implementations could drop it when better algorithms are know (similar as what OWL 2 does by allowing implementations to only cover datatypes that can be mapped to system primitives). I also added an appendix with proofs that show how the regimes satisfy the conditions on extensions of BGP matching and fixed al broken link and mark-up problems. @Chime: I moved one </p> in your section to make the validator happy: <p>This should result in the following bindings as a result of the rules and the triples (2)-(7) from a SPARQL service that implements the RIF Core entailment regime:**</p>** (<- was after the following table before) What is no longer in the Direct Semantics regime is the "combined semantics", which modified OWL 2 Direct Semantics to also take into account non-logical stuff such as annotations. I much prefer not changing the entailment relations from other specs. I can see that users want to query for annotation, but I would prefer to at least have an additional custom regime that is an extension of the Direct Semantics regime. Any opinions? Put it back in? Add an additional extended direct semantics regime? Wait whether we get complaints? I think the regimes are now in a pretty good shape for the F2F. I am happy to hear your opinion :-) Birte -- Dr. Birte Glimm, Room 306 Computing Laboratory Parks Road Oxford OX1 3QD United Kingdom +44 (0)1865 283529
Received on Friday, 19 March 2010 11:49:58 UTC