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Re: tests and inference? (and UNSAID)

From: Steve Harris <S.W.Harris@ecs.soton.ac.uk>
Date: Tue, 21 Dec 2004 18:27:40 +0000
To: RDF Data Access Working Group <public-rdf-dawg@w3.org>
Message-ID: <20041221182740.GM23271@login.ecs.soton.ac.uk>

On Mon, Dec 20, 2004 at 09:57:01PM +0000, Andy Seaborne wrote:
> >>My engine has no way to turn off inference (though it wouldn't be hard to
> >>add globaly), but I'd like it if that was possible on a per-statement way
> >>via the query language.
> >
> >
> >I'm not sure what you mean; it makes more sense, to me, to specify what
> >you're querying against in the FROM clause. If we wanted explicit
> >support for "turning RDFS inferencing off" in SPARQL, I'd expect it
> >to look something like:
> >
> >	SELECT ?C FROM rdfs(mydata.rdf) WHERE ( :x rdf:type ?C).
> >vs.
> >	SELECT ?C FROM <mydata.rdf> WHERE ( :x rdf:type ?C).
> 
> Like /2004JulSep/0363.html, I am presuming that graphs and their closures 
> are different graphs to query.  i.e. mydata.rdf and rdfs(mydata.rdf) are 
> different graphs.

That is certainy true in 3store.
 
> It occurred to me, inspired by Simon's datatyping graphs, that one way to 
> have both inference and non-inference over the same graph in the same query 
> is to attach the same ABox twice, once with a TBox:
> 
> SELECT *
> FROM <mydata-rdfs> # The RDF closure of mydata.rdf
> GRAPH <mydata.rdf> # The RDF
> 
> Then a pattern like:
> 
>     ( :x rdf:type ?C)
> 
> is answered by the RDFS closure  but
> 
>     SOURCE <mydata.rdf> (?direct rdfs:subClassOf :C)
> 
> only gives the asserted subclass relationships.
> 
> This could help with Steve's case where it isn't a matter of turning 
> inference off (either per query or per triple pattern) because in that case 
> there would not be the two different graphs.  There is no <mydata.rdf> to 
> query.

Yes, but only if you know that graph(s) the ground facts are in.

- Steve 
Received on Tuesday, 21 December 2004 18:27:43 GMT

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