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Can you query rdf:List easily? (WAS Re: update on vCard edits and The Compromise)

From: Harry Halpin <hhalpin@ibiblio.org>
Date: Fri, 27 Jul 2007 18:38:11 -0400
Message-ID: <46AA73D3.7010508@ibiblio.org>
To: Bijan Parsia <bparsia@cs.man.ac.uk>
Cc: Bruce D'Arcus <bdarcus@gmail.com>, bnowack@appmosphere.com, Garret Wilson <garret@globalmentor.com>, Semantic Web <semantic-web@w3.org>

Is it indeed difficult or impossible to write a SPARQL query over
rdf:List, particulary with the use of owl:sameAs as in:

 <vCard:additionalNames rdf:parseType="Collection">
      <rdf:Description owl:sameAs="Edward"/>
      <rdf:Description owl:sameAs="Reeves"/>
 </vCard:additionalNames>. 

Can someone tell me precisely why and if so, does rdf:Seq help?

Currently consensus is heavily drifting towards rdf:List, but querying
in SPARQL is important.

          -harry

Bijan Parsia wrote:
> On Jul 26, 2007, at 2:39 PM, Harry Halpin wrote:
>
>> Bruce D'Arcus wrote:
> [sni[]
>>> I'm now totally lost.
>>>
>>> Everyone I have talked to has discouraged use of rdf:Seq. AFAIK, you
>>> cannot really query it reliably with SPARQL either, though am not sure
>>> of that.
>> Is that true?
> [snip]
>
> Which? That everyone bruce has talked to discourages use of rdf:Seq? I
> don't know. I certainly do so discourage. But I discourage use of
> rdf:List too :)
>
> I don't know about "reliably". Someone later in the thread gave a
> pretty good query for getting at the values of containers. Ordering
> generally is done by term sorting, so _1 _2, etc. should work fine.
>
> There are implementation specific extensions (both actual and
> possible) e.g.
>     http://thefigtrees.net/lee/sw/sparql-faq#transitiv8
>
> Back in the day, some engines had trouble with large numbers of
> properties, so the coined properties in a seq could cause trouble if
> one had no special ordering of them (e.g., if you naively mapped
> properties to tables, that could suck). But that strikes me as
> implementor lameness, which is also to be discouraged. :)
>
> Cheers,
> Bijan.
>
>


-- 
		-harry

Harry Halpin,  University of Edinburgh 
http://www.ibiblio.org/hhalpin 6B522426
Received on Friday, 27 July 2007 22:38:40 UTC

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