Re: subgraph/entailment

On 8 Sep 2005, at 10:37, Seaborne, Andy wrote:
> For SPARQL to be useable, it must be possible to make queries  
> against the exact triples in the base data.  Other modes shoudl  
> also be possible determined by what service/graph/repository is  
> being queried.
> It must be possible to access the base data for SPARQL to be  
> useable for any application that is involved in building a graph  
> while at the same time accessing it.  I coined the term "zero- 
> entailment" as I couldn't find extsing terminology.
> I understand this to be part of the "Local Query" requirement. I  
> had in mind that the query language be usable in applications that  
> require access to the base data so they can add new triples, and  
> they themselves deliver inference services to other applications.

The point I am raising is in the case you want to be compliant with  
RDF MT, which seems to me necessary for SPARQL: we don't want SPARQL  
to be unable to correctly answer queries under the official standard  
RDF-MT semantics. The RDF-MT semantics introduces two entailments:  
the simple one, where basically the graph is un-altered, and  
therefore it corresponds to what above you refer to as "exact  
triples" or "zero entailment". Then, there is the RDF-entailment. If  
you take seriously the official standard RDF-entailment as defined in  
the official standard RDF-MT semantics, I say that you have to have  
the behaviour that Bijan and me were arguing about.


Received on Thursday, 8 September 2005 10:56:20 UTC