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

On 29 Sep 2011, at 17:31, Pierre-Antoine Champin wrote:
> SPARQL states that:
>> An RDF Dataset comprises one graph, the default graph, which does
>> not have a name, and zero or more named graphs, where each named
>> graph is identified by an IRI.

Well that's SPARQL. We are talking about RDF Concepts. It says [1]:

Each named graph is a pair consisting of an IRI (the graph name), and an RDF graph. Graph names are unique within an RDF dataset.

It avoids words like “identify” and “denote”.

> So I would argue that, in the end of the day, neither of the following
> sentence is accurate:
>  a named graph is identified by an IRI
>  a named graph is labeled by an IRI
> but in fact:
>  a named graph is labelled by a resource

That's not accurate at all.

A named graph is an <IRI,graph> pair. The IRI is called the graph name.

As written in the ED, the relationship between the IRI and the graph is neither “identifies” nor “labels”; it is “is graph name of”. No relationship between the resource denoted by the IRI and the graph is implied by the wording in the ED.

> (imagine for example a owl:sameAs statement between two graphs IRI in a
> SPARQL engine supporting OWL inference; what would that mean?)

owl:sameAs means that two terms denote the same resource. As written in the ED, use of those terms as graph names is entirely orthogonal to that.

I think that's a good thing. Named graphs are key to trust and provenance. Trust and provenance must happen at a lower level in the stack, before reasoning and inference kick in. W3C's version of the layer cake, where trust sits above reasoning, cannot work. The moment you reason with OWL over untrusted data, you're fucked.



Received on Friday, 30 September 2011 10:03:01 UTC