Hi Rita, On Jun 4, 2010, at 2:24 AM, Rita Marnau wrote: > The second argument of M. Connor was, that SPARQL has no sound semantics [2]. > > "What's worse, SPARQL does not even have formally sound semantics > in terms of RDF. [..] there > are no guarantees about the soundness of results returned by a SPARQL > query even on an RDF ontology." > > I there a de facto standard for the SPARQL semantics, used by each reasoners? > Or do you just trust in the reasoners you choosed?
I believe he might be referring to the treatment of blank nodes in RDF versus SPARQL. This is a general issue with RDF and it looks like it will be addressed by W3C in the future. See for example http://www.w3.org/2009/12/rdf-ws/papers/ws05 http://www.w3.org/2009/12/rdf-ws/papers/ws23 With regards to SPARQL, this is however only a theoretical problem, because the SPARQL engines that I know about all implement the semantics that blank nodes are simply nodes without a URI, and this is consistent with what most people expect in practice. So in a sense, SPARQL already implements the "right" semantics, while the underlying problem will likely be addressed on the RDF layer in the future. Having said this, I would welcome real-world scenarios where the "lack of guarantees about the soundness" of SPARQL is affecting anyone. I have never ever had such a case. Maybe Martin knows more. Note that his message you have quoted is three years old. The community has moved on. There are dozens of SPARQL implementations, and one SQWRL implementation. Regards, Holger -- You received this message because you are subscribed to the Google Group "TopBraid Suite Users", the topics of which include TopBraid Composer, TopBraid Live, TopBraid Ensemble, SPARQLMotion and SPIN. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/topbraid-users?hl=en
