Re: Blank nodes semantics - existential variables?

On 6/30/20 7:48 PM, Holger Knublauch wrote:> As a practical example, 
several years ago I spoke to a couple of
> database vendors because if you uploaded an RDF file with blank nodes, 
> their implementations were returning new blank nodes for the same data 
> with each query. As a result of this, it basically wasn't possible to do 
> incremental graph traversals or even delete nodes that you had fetched 
> in previous queries. 

Yup.  That's an excellent illustration of something we REALLY need to 
fix.  From the perspective of someone new to RDF, that's totally broken.

I used to think that Skolem URIs could be a viable workaround for that 
problem, but I've since concluded that really we should move to a 
higher-level syntax that doesn't expose blank nodes (or their Skolem 
equivalents) to the RDF developer.   Unfortunately this would require a 
SPARQL upgrade -- a non-trivial task -- which is why I think the design 
of an RDF successor would be a good PhD topic.

David Booth

Received on Thursday, 2 July 2020 01:20:17 UTC