W3C home > Mailing lists > Public > public-swd-wg@w3.org > March 2009

Re: [SKOS] subsection of Primer about ISSUE-36

From: Antoine Isaac <aisaac@few.vu.nl>
Date: Tue, 24 Mar 2009 11:51:58 +0100
Message-ID: <49C8BB4E.2060402@few.vu.nl>
To: Alistair Miles <alistair.miles@zoo.ox.ac.uk>
CC: SWD WG <public-swd-wg@w3.org>
Hi Alistair,

Interesting comments, thanks!
I guess that though in many cases the outcome of the two options would be the same, the formal semantics are completely different ;-)

One question though: should "GRAPH" really replace "FROM NAMED", or just be added to the existing queries?

Antoine


> Hi Antoine,
> 
> Sorry for not responding sooner on this, for the most part it looks
> fine, however I would change the SPARQL queries to use the GRAPH
> keyword instead of FROM NAMED, see below.
> 
> On Sun, Dec 14, 2008 at 08:09:02PM +0100, Antoine Isaac wrote:
>> Hi everyone,
>>
>> About the following action:
>>
>>>    [PENDING] ACTION: Antoine propose 1 or 2 SPARQL examples showing
>>>    named graph usage [recorded in
>>>    [36]http://www.w3.org/2008/11/25-swd-minutes.html#action14]
>> I'd like to propose to add to the Primer the sub-section below (it would be at the very end of the Primer).
>> I hope this capture the spirit of our resolution for ISSUE-36 [1] appropriately, while not going too much in the direction of not yet stabilized practices.
>>
>> Feedback of the WG is highly welcome!
>>
>> Cheers,
>>
>> Antoine
>>
>> [1] http://www.w3.org/2006/07/SWD/track/issues/36
>>
>> ===============
>>
>> 5.3 SKOS, RDF Datasets and Information Containment
>>
>> In a context of networked KOSs, some applications may require tracking 
>> provenance or ownership of SKOS statements, for instance for trust 
>> purposes. A specific issue is how to establish explicit links between a 
>> concept scheme and every piece of information that is stated in the 
>> original KOS it represents, including for instance semantic relationships 
>> between concepts. 
>>
>> Such functionality, albeit identified as a candidate requirement [SKOS-UCR], is currently outside the scope of SKOS. In RDF, statements comes as context-free triples, which makes it difficult to represent containment and provenance.
>>
>> However, solutions for such problems have been proposed, like named graphs [NAMED-GRAPHS], and the use of RDF Datasets in SPARQL [SPARQL]. A SKOS concept scheme can be related to an RDF Dataset, or even asserted to be such a Dataset, which enables to create SPARQL queries dealing with some form of provenance/containment. Continuing the example of Section 3.2, and assuming that ex1:referenceAnimalScheme and ex2:catScheme have been managed as appropriate RDF Datasets (here, named graphs), the query
>>
>> SELECT  ?x ?y
>> FROM NAMED <ex2:catScheme>
>> WHERE   { ?x skos:broader ?y }
> 
> SELECT ?x ?y
> WHERE {
>   GRAPH ex2:catScheme {
>     ?x skos:broader ?y
>   }
> }
> 
>> may return (ex2:abyssinian, ex1:cat) as a result, while this tuple would 
>> not appear among the results of 
>>
>> SELECT  ?x ?y
>> FROM NAMED <ex1:referenceAnimalScheme>
>> WHERE   { ?x skos:broader ?y }
> 
> SELECT ?x ?y
> WHERE {
>   GRAPH ex1:referenceAnimalScheme {
>     ?x skos:broader ?y
>   }
> }
> 
>> Readers should nevertheless be aware that these mechanisms have not been widely used at the time of writing, and that different standard practices could emerge in the future.
>>
>>
> 
Received on Tuesday, 24 March 2009 10:52:32 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Tuesday, 24 March 2009 10:52:33 GMT