- From: Axel Polleres <axel.polleres@deri.org>
- Date: Sat, 9 Jan 2010 02:08:13 +0000
- To: SPARQL Working Group <public-rdf-dawg@w3.org>
This is a summary of some of the issues/errata to definitions in the current query spec that we stumbled over in some of the discussions on entailment. While I don't think it makes sense to strive to resolve any of these for the next WDs, I'd keep them ready for discussion in one of the coming TCs after publication (Please let me know if I forgot anything or there are any other improvements/errata): 1) consistency requirement for entailment regimes Issue text: For efficient implementations, it might be undesirable to enforce consistency checking, e.g. for RDFS. So, in order to follow: "The effect of a query on an inconsistent graph is not covered by this specification, but must be specified by the particular SPARQL extension." My (Axel- chairthatoff) interpretation is that I don't see that this implies that an extension has to uniquely define the behavior on inconsistent graphs, actually it could leave several options open (e.g. for implementations that do or don't perform consistency checking.) 2) uniqueness of scoping graph The current spec of extending BGP matching requires uniqueness of the scoping graph, whereas actually the definition of a scoping graph for simple entailment is only unique up to homomorphic (i.e. simple) equivalence: "1 -- The scoping graph, SG, corresponding to any consistent active graph AG is uniquely specified and is E-equivalent to AG." It is there fore discussed to clarify this condition, e.g.: "The scoping graph, SG, corresponding to any consistent active graph AG is uniquely (modulo simple equivalence) specified and is E-equivalent to AG." 3) Definition of RDF-B ""The term RDF-L denotes the set of all RDF Literals, RDF-B the set of all blank nodes in RDF graphs" Hmmm, why "in RDF graphs" and in *which* graphs? It might be clearer/easier to simply drop "in RDF graphs", or to specify which graphs are talked about here. 4) Definition of Pattern Instance Mapping Birte's suggested clarafication, cf. http://lists.w3.org/Archives/Public/public-rdf-dawg/2010JanMar/0029.html
Received on Saturday, 9 January 2010 02:08:47 UTC