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Re: RDF dataset semantics again

From: Sandro Hawke <sandro@w3.org>
Date: Thu, 23 Aug 2012 07:11:17 -0400
Message-ID: <50360FD5.6020603@w3.org>
To: public-rdf-wg@w3.org
On 08/23/2012 05:57 AM, Antoine Zimmermann wrote:
>
>
> Le 22/08/2012 18:37, Sandro Hawke a écrit :
>> On 08/22/2012 12:30 PM, Antoine Zimmermann wrote:
>>>
>>>>
>>>> I could live with it if there were a syntactic sugar, probably 
>>>> involving
>>>> curly braces. :-)
>>>
>>> Yes, the syntax is not really practical.
>>>
>>
>> Indeed. But, yes, it's a nice way to think about the semantics. I
>> understood it to be a way the WG was not okay with.
>
>
> My impression was that the group found the idea reasonable, possibly 
> appealing, but due to a total absence of implementation of this 
> solution, and no experience with it thereby, it was not a good idea to 
> standardise such a thing.
>
>

I don't recall hearing that, but it makes sense.

>> One bit that doesn't quite work is that some of the use cases require
>> blank nodes to be shared between named graphs. That would be rather
>> strange with this literal-strings model.
>
>
> It is in principle possible to define the datatype such that the value 
> space is not exactly the set of RDF Graphs, but rather "RDF Graphs 
> where some bnodes can be labelled". The bnode labels are made disjoint 
> from URIs, so they can be distinguished apart from normal names, but 
> they would not be purely local to the graph.
>

I'm not sure you'd need to change the value space.   Existing (2004) 
g-snaps can share bnodes, it's just the way the syntaxes are parsed 
doesn't currently allow one to indicate that.     So, those 
graphs-in-quotes would have to be parsed as some new kind of thing -- a 
document-fragments, instead of a document.     A little problem, IMHO, 
not a big one.

IMHO we should at some point sketch out this solution and its 
isomorphism to whatever we settle on.    Maybe not actually assign a 
vocabulary to it, lest people use it and not be interoperable. 
Alternatively, it might be the way RDF/XML folks play in the named-graph 
space.   (That's a Time Permitting deliverable in our charter.)

     -- Sandro

>
>
>>
>> -- Sandro
>>
>>>>
>>>> - s
>>>>
>>>>>>
>>>>>> Another (uglier!) representation would be
>>>>>> <g> ex:hasGraph
>>>>>> <data:text/turtle;charset=UTF-8,%3Cs%3E%20%3Cp%3E%20%3Co%3E> .
>>>>>>
>>>>>> Which would also allow you to make statements about the quoted graph
>>>>>> <data:text/turtle;charset=UTF-8,%3Cs%3E%20%3Cp%3E%20%3Co%3E> dc:date
>>>>>> "2012-08-22T14:29:23Z"^^xsd:dateTime .
>>>>>
>>>>> +1
>>>>>
>>>>>>
>>>>>> - Steve
>>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>>
>>>
>>
>>
>>
>
Received on Thursday, 23 August 2012 11:11:23 UTC

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