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Re: Agenda Topic / Issue: Clarify the meaning of "ignore" with respect to attributes that have no legal value

From: Hausenblas, Michael <michael.hausenblas@deri.org>
Date: Fri, 11 Sep 2009 08:54:22 +0100
Message-ID: <C6CFC0BE.83FA%michael.hausenblas@deri.org>
To: "Ivan Herman" <ivan@w3.org>, "Tore Eriksson" <tore.eriksson@po.rd.taisho.co.jp>
Cc: "Mark Birbeck" <mark.birbeck@webbackplane.com>, "RDFa TF list" <public-rdf-in-xhtml-tf@w3.org>, "Shane McCarron" <shane@aptest.com>

> Unfortunately, at least at the moment, there is no formal specification
> for named graphs.

Agree. And almost everyone I know agrees as well that this should be fixed
in an updated RDF core (that is, model) in the very near future. Any plans?

Cheers,
      Michael

-- 
Dr. Michael Hausenblas
LiDRC - Linked Data Research Centre
DERI - Digital Enterprise Research Institute
NUIG - National University of Ireland, Galway
Ireland, Europe
Tel. +353 91 495730
http://linkeddata.deri.ie/
http://sw-app.org/about.html



> From: Ivan Herman <ivan@w3.org>
> Organization: World Wide Web Consortium
> Date: Fri, 11 Sep 2009 09:49:52 +0200
> To: Tore Eriksson <tore.eriksson@po.rd.taisho.co.jp>
> Cc: Mark Birbeck <mark.birbeck@webbackplane.com>, RDFa TF list
> <public-rdf-in-xhtml-tf@w3.org>, Shane McCarron <shane@aptest.com>
> Subject: Re: Agenda Topic / Issue: Clarify the meaning of "ignore" with
> respect  to attributes that have no legal value
> Resent-From: RDFa TF list <public-rdf-in-xhtml-tf@w3.org>
> Resent-Date: Fri, 11 Sep 2009 07:50:31 +0000
> 
> 
> 
> Tore Eriksson wrote:
>> Mark Birbeck <mark.birbeck@webbackplane.com> wrote:
>>> The final piece of the jigsaw is to bring back in the earlier point,
>>> i.e., that the spec allows us to create a triple from 'foobar'
>>> provided that we don't put it into the default graph. In this case my
>>> parser might place the 'unknown' triple into a separate graph:
>>> 
>>>   Default graph:
>>>     _:a foaf:name "Mark" .
>>> 
>>>   Graph A:
>>>     <#shane> ex:blah _:a .
>>> 
>>> Now, as you can see, even though it's in a separate graph, I could
>>> still run a SPARQL query over *both* graphs to yield the following
>>> triples:
>>> 
>>>   <#shane> ex:blah _:a .
>>>   _:a foaf:name "Mark" .
>>> 
>>> And since the parsing algorithm caused us to generate a bnode despite
>>> not understanding 'ex:blah', then the triples in the two separate
>>> graphs are 'aligned'.
>> 
>> My understanding from reading "Named Graphs, Provenance and Trust" [1],
>> is that blank nodes can't be shared between graphs, making this type of
>> query impossible. Graph A has to be a superset of the default graph for
>> this to work.
>> 
> 
> Unfortunately, at least at the moment, there is no formal specification
> for named graphs. Alas!, [1] does not constitute an authoritative
> reference for a standard (although it may very well be the way to do it
> technically!). Note that the SPARQL document does not make such strong
> statements, so strictly referring to SPARQL Mark is probably right. But,
> at the moment, this is a grey area:-(
> 
> Ivan
> 
> 
>> [1] http://www2005.org/cdrom/docs/p613.pdf
>> 
>> Regards,
>> 
>> Tore Eriksson
>> 
>> _______________________________________________________________
>> <> dc:creator [
>>    foaf:name "Tore Eriksson",
>>              "トーレ エリクソン"@jp;
>>    foaf:mbox_sha1sum "2bd9291b301f112775e118f96eb63314594b1a86";
>>    foaf:workplaceHomepage <http://www.taisho.co.jp/> ].
>> 
>> 
>> 
> 
> -- 
> 
> 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 Friday, 11 September 2009 07:55:05 GMT

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