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Re: SPARQL-friendly alternative to rdf:Lists?

From: David Booth <david@dbooth.org>
Date: Fri, 11 Oct 2013 23:57:25 -0400
Message-ID: <5258C8A5.7090901@dbooth.org>
To: Axel Polleres <axel@polleres.net>
CC: semantic-web <semantic-web@w3.org>
Hi Axel,

The problem is that SPARQL property paths do not allow the *ordering* of 
the elements to be easily retained in the result set.  For example, a 
property path like this obtains all elements, but does not guaranteed 
their order in the result set:

   { :list rdf:rest*/rdf:first ?element }

David

On 10/11/2013 11:45 PM, Axel Polleres wrote:
> FWIW, just to mention that property paths in SPARQL1.1 should have
> made it a lot easier to query lists in SPARQL. Cf. examples at:
> http://www.w3.org/TR/sparql11-query/#propertypath-examples (also
> contains an example to query the elements of a list) Would that cover
> your use case? If not, what'd be missing?
>
> best, Axel
>
>
> -- Prof. Dr. Axel Polleres Institute for Information Business, WU
> Vienna url: http://www.polleres.net/  twitter: @AxelPolleres
>
> On Oct 11, 2013, at 4:02 PM, David Booth <david@dbooth.org> wrote:
>
>> rdf:Lists are notoriously difficult to use in SPARQL if one wishes
>> to retain the *order* of the items in the list.  James Leigh and
>> David Wood made a nice proposal a few years ago to address this
>> problem directly at the RDF level,
>> http://www.w3.org/2009/12/rdf-ws/papers/ws14 but for whatever
>> reasons, that work was not included in the charter of the current
>> RDF working group.  As a result people often use some other means
>> of representing ordered lists in RDF, such as by [item, index]
>> pairs.
>>
>> For those who use an alternate way to represent an *ordered* list
>> of items in RDF (instead of rdf:List), I am wondering:
>>
>> 1. What *ordered* list representation do you prefer, and why?
>>
>> 2. Have there been any efforts toward standardizing alternative
>> *ordered* list representations in RDF?  E.g., has anyone written up
>> a spec on how they prefer to do it?
>>
>> Thanks, David
>>
>
>
>
>
Received on Saturday, 12 October 2013 03:57:55 UTC

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