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Re: RDF-ISSUE-5 (Graph Literals): Should we define Graph Literal datatypes? [RDF Graphs]

From: Ivan Herman <ivan@w3.org>
Date: Sun, 6 Mar 2011 09:28:44 +0100
Cc: RDF Working Group WG <public-rdf-wg@w3.org>
Message-Id: <EB6B1E12-927A-4A20-A363-239C41A86A70@w3.org>
To: Richard Cyganiak <richard@cyganiak.de>
Richard, 

I just want to clarify one thing. I have the impression that many (if not all) of your arguments would also apply to TriG, ie, they are bound to graph literals. Is your opinion that

- we should clarify the g-* concepts in terms of _concepts_
- we should not define any extension of any serialization (maybe with the possible exception of N-Quads) 
- declare victory

This is a perfectly consistent approach, although I am not convinced about it yet:-). I would just like to understand your viewpoint...

Thanks

Ivan




On Mar 5, 2011, at 18:46 , Richard Cyganiak wrote:

> On 5 Mar 2011, at 16:36, Ivan Herman wrote:
>>> Anyone could trivially define such datatypes. And once that is done, tool vendors could easily add support for them.
>>> 
>>> Given the relative ease of doing this, if there was actual user demand for such datatypes, then surely someone would have already defined them, and they would have seen some adoption.
>> 
>> I think it is a little bit more than that. Defining such datatypes requires to define the lexical and value spaces. While lexical spaces might be easy, the value space is...
> 
> The value space would be RDF graphs, as defined in RDF Concepts since 2004. The only question would be the scope of blank nodes, but I don't buy the argument that no one ever defined a graph literal datatype because they all became stuck in analysis paralysis on the bNode question.
> 
>> hm, g-snaps? Aren't we just discussing this in the GRAPH discussions?
> 
> I thought the [Graphs] discussion was about extending what's defined in RDF Concepts with some new concepts that would support handling of multiple graphs in a standard way. I'd think that compatibility with SPARQL's RDF Dataset and Graph Store would be pretty high up on the wish list for these new concepts. I think it's pretty clear that graph literals alone do not address this.
> 
> Best,
> Richard
> 
> 
>> 
>> Ie, I am not sure that the fact that this has not been done is a sign for the community not wanting this. It is because the mess that we are discussing for the value space is still a mess...
>> 
>> Ivan
>> 
>> 
>>> It is my strong belief that standardization efforts should focus on codifying existing practice and not invent new speculative things.
>>> 
>>> Richard
>>> 
>>> 
>>> 
>>>> 
>>>> http://www.w3.org/2011/rdf-wg/track/issues/5
>>>> 
>>>> Raised by: Sandro Hawke
>>>> On product: RDF Graphs
>>>> 
>>>> We could define datatypes, such as ser:rdfxml and ser:turtle, whose
>>>> lexical space is the set of valid document strings in RDF/XML, Turtle,
>>>> etc, and whose value space contains the corresponding RDF graphs.
>>>> 
>>>> This would allow people to use ordinary RDF tools to express facts involving RDF graphs, such as that some graph was obtained from some URI at some point in time, or that some person claims some graph is true or false.
>>>> 
>>>> This would address some of the use cases for quads, reification, named
>>>> graphs, etc, with a mechanism that is very simple to understand and
>>>> relatively easy to implement.
>>>> 
>>>> Languages (like Turtle and RDF/XML) could be extended to provide
>>>> syntactic sugar for these literals, much as Turtle provides a nicer
>>>> syntax for numbers, but that is not necessary for these literals to be
>>>> useful and is not part of this proposal.
>>>> 
>>>> Some discussion in http://lists.w3.org/Archives/Public/public-rdf-wg/2011Mar/0130.html
>>>> 
>>>> 
>>>> 
>>> 
>>> 
>> 
>> 
>> ----
>> Ivan Herman, W3C Semantic Web Activity Lead
>> Home: http://www.w3.org/People/Ivan/
>> mobile: +31-641044153
>> PGP Key: http://www.ivan-herman.net/pgpkey.html
>> FOAF: http://www.ivan-herman.net/foaf.rdf
>> 
>> 
>> 
>> 
>> 
> 


----
Ivan Herman, W3C Semantic Web Activity Lead
Home: http://www.w3.org/People/Ivan/
mobile: +31-641044153
PGP Key: http://www.ivan-herman.net/pgpkey.html
FOAF: http://www.ivan-herman.net/foaf.rdf






Received on Sunday, 6 March 2011 08:27:06 UTC

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