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

From: Phil Archer <parcher@icra.org>
Date: Mon, 30 Jul 2007 12:44:03 +0100
Message-ID: <46ADCF03.8060206@icra.org>
To: Semantic Web <semantic-web@w3.org>

Just a quick comment on this thread.

We've faced something a little similar in the POWDER WG [1] where we're 
working on defining a set of resources [2], for example, all resources 
on example.com. That's quite easy for us:

<wdr:ResourceSet>
  <wdr:includeHosts>example.com</wdr:includeHosts>
</wdr:ResourceSet>

But note the plural in the property name. Actually this takes a white 
space separated list of hosts so if you want both example.com and 
example.org in your resource set you do this:

<wdr:ResourceSet>
  <wdr:includeHosts>example.com example.org</wdr:includeHosts>
</wdr:ResourceSet>

No rdf:list, even though, well, it's a list encoded in RDF. We're 
working on datatype doc that should support this formally, currently in 
un-official form at [3]. The thinking here being that, in order to 
process POWDER, you need to do a little bit of non-Sem Web processing so 
delivering the parameters that define a Resource Set as a white space 
separated list is OK and probably pretty efficient. The recent 
discussion on the applicability of rdf:List (and to a lesser extent Alt 
and Seq) seems to suggest that keeping away from rdf:List was good idea too?

What we really want, in a slightly different context, is a single SPARQL 
query to return the items in a Collection, but I guess that's just 
asking to much!

Phil.

[1] http://www.w3.org/2007/powder/
[2] http://www.w3.org/TR/2007/WD-powder-grouping-20070709/
[3] http://www.dicom.uninsubria.it/~andrea.perego/powder/?doc=xsd


Danny Ayers wrote:
> I'm late to the thread, so apologies if this has been covered already:
> 
> Harry's data, reworked to use literals, would look something like:
> 
> _:lola
>  vCard:additionalNames  ( "Edward" "Reeves"  ) .
> 
> - the object here is a list, so the plural-named property seems reasonable.
> 
> Similar information could be conveyed as:
> 
> _:lola vCard:additionalName "Edward" ;
>          vCard:additionalName "Reeves" .
> 
> (or similar, intermediated with an rdf:Bag)
> 
> What I'm wondering is, is there any reason (beyond saving space) for
> not using both forms simultaneously? Have the benefits of rdf:List
> along with SPARQL-friendliness..?
> 
> btw, here's a fun way of querying lists (not *that* ugly a beast):
> 
> SELECT ?w ?x ?y ?z
> {
>    OPTIONAL {
>      ?person vCard:additionalNames ( ?w ) .
>    }
>    OPTIONAL {
>      ?person vCard:additionalNames ( ?w ?x ) .
>    }
>    OPTIONAL {
>      ?person vCard:additionalNames ( ?w ?x ?y ) .
>    }
>    OPTIONAL {
>      ?person vCard:additionalNames ( ?w ?x ?y ?z ) .
>    }
> }
> 
> Cheers,
> Danny.
Received on Monday, 30 July 2007 11:44:40 UTC

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