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Re: why I don't like named graph IRIs in the DATASET proposal

From: Richard Cyganiak <richard@cyganiak.de>
Date: Wed, 5 Oct 2011 17:53:47 +0100
Cc: Pierre-Antoine Champin <pierre-antoine.champin@liris.cnrs.fr>, "public-rdf-wg@w3.org" <public-rdf-wg@w3.org>
Message-Id: <4A70291F-2D21-4E62-9E61-77EECB321FC7@cyganiak.de>
To: Ian Davis <Ian.Davis@talis.com>
On 5 Oct 2011, at 15:03, Ian Davis wrote:
>> >> Inference is defined over RDF graphs, not over collections of unasserted RDF graphs.
>> >
>> > While I agree with this statement, isn't it the case that most graph stores do inference over the collection of graphs in a dataset?
>> 
>> Most graph stores don't do inference at all.
>> 
> Of the ones that do can you list some that don't operate over the collection of graphs as a single unit?

Sorry, I don't have a comprehensive matrix of triple store features.

>> > Given these two graphs in a single graph store and a schema that says ex:ancestor is transitive then I'm sure many inference enabled systems will answer true if asked whether :c is an ancestor of :a
>> >
>> > :G1 { :a ex:ancestor :b }
>> >
>> > :G2 { :b ex:ancestor :c }
>> >
>> > I'm pretty sure BigOWLIM does this, possibly others too.
>> 
>> Like some other stores, BigOWLIM probably just by default places the union of all named graphs into the default graph. If it then does per-graph inference, then you get the effect you describe above when querying the default graph.
> 
> No, the default graph behaviour is configurable in BigOWLIM I believe.

That's what I said. (Or at least what I meant.)

> However I think that behaviour isn't really relevant to whether inference is done on a per graph basis or over a collection of graphs.

The effect you described above is consistent with a store that does only per-graph inference and is configured to have the union of all named graphs in the default graph.

Best,
Richard
Received on Wednesday, 5 October 2011 16:54:17 GMT

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