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Re: [dcat] rdf graphs and documents

From: Chris Beer <chris@e-beer.net.au>
Date: Fri, 30 Apr 2010 15:46:24 +1000
Message-Id: <8C434CC1-7236-498F-B42C-36FA2AAE8A4F@e-beer.net.au>
To: Erik Wilde <dret@berkeley.edu>
Cc: William Waites <ww-keyword-okfn.193365@styx.org>, Cory Casanave <cory-c@modeldriven.com>, "public-egov-ig@w3.org" <public-egov-ig@w3.org>, Richard Cyganiak <richard@cyganiak.de>
I seriously ( unless my RDF understanding is flawed ) would of assumed  
that you cannot by definition have a rdf:graph element. The graph has  
to be by nature dynamic, that is, it is, graph can only exist when  
subject, predicate, and object are known. It could act as a container  
for the 3 rdf elements, but in and of itself I see no point in  
defining it. I guess what I'm saying, by example, that there is no use  
in trying to define x in algebra, as x could be anything, or more  
importantly, x by itself could be anything. Or to put it another way -  
is there any point in defining a "page containing any combination of  
elements" within HTML - the concept of a page is the end result of  
markup, just as a graph is the end result of any rdf markup. (then  
again, prehaps it is worth defining graph as a rdf doctype or  
something). I'm no expert, so be gentle if I'm completely on the wrong  
track here :)

Cheers

Chris

Sent from my iPhone

On 30/04/2010, at 10:19, Erik Wilde <dret@berkeley.edu> wrote:

> hello.
>
>> We have rdf:subject, rdf:predicate, rdf:object but
>> there is no such thing as rdf:graph to mention the fourth element.  
>> I've
>> invented an equivalent, but does anyone know if there is such a
>> predicate defined anywhere? Is it worth attempting to suggest an  
>> update
>> to the core rdf vocabulary to have this added (also with a  
>> commensurate
>> rdf:Graph class)?
>> We are lacking in tools for talking about graphs in rdf itself it  
>> seems...
>
> i think this is the grand debate about RDF2 and whether named graphs  
> should become part of RDF itself. thanks for your thoughtful email,  
> you described it much better than i was able to do it. the point is  
> that RDF triples in the current RDF world have no coherence, you  
> might find them in various "documents" at various URIs, or all in  
> the same triple store; semantically, there is no difference. for  
> metamodels with a "document" level, there is coherence, and it  
> matters in which document you find a substructure of some data. this  
> is what i wanted to say by saying that "RDF has no documents", but  
> you explained it in a much better way. thanks!
>
> cheers,
>
> dret.
>
Received on Friday, 30 April 2010 05:46:32 GMT

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