Re: New Proposal (6.1) for GRAPHS

Thanks Sandro.

In general, I think this is the way to go. Few comments

1. You say, in 

http://www.w3.org/2011/rdf-wg/wiki/Graphs_Design_6.1#The_Labeling_Relation

that 

"A trig document expresses an rdf:hasGraph relation between the graph label object and the RDF Graph"

do we really need to describe this in term of what seems to be a bona fide RDF triple? If we do so, how do we define the range of the rdf:hasGraph property? Obviously, the range does not include literals (we do not have graph literals) but then the range should include URI references and/or bnodes. But, in fact, the range should be graphs... Aren't graphs, as abstract terms, beyond what RDF triples describe? Aren't we opening up some flood gates here?

My alternative would be to describe 'hasGraph' as NOT an RDF property. However, we can define a class, much as your rdf:Graph class (say, rdf:GraphLabel) and say that:

<u> { a b c. }

entails 

<u> rdf:type rdf:GraphLabel

And we would also have something like

rdf:Graph rdfs:subClassOf rdf:GraphLabel


2. related to the Extension part:

http://www.w3.org/2011/rdf-wg/wiki/Graphs_Design_6.1#Extensions

Is there any reason why we could not rdf:GraphStateResouce in the current spec? By having it as a separate class it does not interfere with applications that require only the basic labeling, but, as you yourself argued for it many times, in some applications (eg, related to Linked Data) having that 'semantics' clearly defined would make sense.

Ivan




On Mar 28, 2012, at 04:23 , Sandro Hawke wrote:

> I've written up design 6 (originally suggested by Andy) in more
> detail.  I've called in 6.1 since I've change/added a few details that
> Andy might not agree with.  Eric has started writing up how the use
> cases are addressed by this proposal.
> 
> This proposal addresses all 15 of our old open issues concerning graphs.
> (I'm sure it will have its own issues, though.)
> 
> The basic idea is to use trig syntax, and to support the different
> desired relationships between labels and their graphs via class
> information on the labels.  In particular, according to this proposal,
> in this trig document:
> 
>   <u1> { <a> <b> <c> }
> 
> ... we only know that <u1> is some kind of label for the RDF Graph <a>
> <b> <c>, like today.  However, in his trig document:
> 
>   { <u2> a rdf:Graph }
>   <u2> { <a> <b> <c> }
> 
> we know that <u2> is an rdf:Graph and, what's more, we know that <u2>
> actually is the RDF Graph { <a> <b> <c> }.  That is, in this case, we
> know that URL "u2" is a name we can use in RDF to refer to that g-snap.
> 
> Details are here: http://www.w3.org/2011/rdf-wg/wiki/Graphs_Design_6.1
> 
> That page includes answers to all the current GRAPHS issues, including
> ISSUE-5, ISSUE-14, etc.
> 
> Eric has started going through Why Graphs and adding the examples as
> addressed by Proposal 6.1:
> http://www.w3.org/2011/rdf-wg/wiki/Why_Graphs_6.1
> 
>     -- Sandro (with Eric nearby)
> 
> 


----
Ivan Herman, W3C Semantic Web Activity Lead
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