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SPARQL Example: [Linking-open-data] Terminology Question concerning Web Architecture and Linked Data

From: Kingsley Idehen <kidehen@openlinksw.com>
Date: Sat, 07 Jul 2007 23:57:10 -0400
Message-ID: <46906096.1030208@openlinksw.com>
CC: Linking Open Data <linking-open-data@simile.mit.edu>, www-tag@w3.org, semantic-web@w3.org

Kingsley Idehen wrote:
> Kingsley Idehen wrote:
>>>  
>> Depends on the characteristics of the property "owl:sameAs" as used 
>> in Tim's "Universe of Discourse" (Data Space) and here is why:
>>
>> Yes, if in Tim's Data Space Definition he asserts that "owl:sameAs" 
>> is an "owl:SymmetricProperty" then his usage is unambiguous, as this 
>> should result in identical triples when you SPARQL against his Data 
>> Space using either URI (assuming we are not modeling the Web as a 
>> single Graph). Of course, this assumes the SPARQL processor has 
>> inference capabilities. Otherwise, "rdfs:seeAlso" would be the 
>> preferred property as this is unambiguous (i.e. the aforementioned 
>> URIs will produce varied Triples without introducing confusion).
> In retrospect, the statement above is *incorrect* since "owl:sameAs" 
> means the URIs in the Domain and Range are to be treated as 
> "Identical".  It's up to RDF Clients / Consumers (e.g. Browsers and 
> SPARQL Processors) to ensure that identical Triples are dereferenced 
> from said URIs. Thus, Tim's usage is unambiguous :-)
>
>
>
All,

Missing from the above is a SPARQL example.
Graph URI: http://www.w3.org/People/Berners-Lee/card#i

Query1:

select distinct ?s ?p ?o
where {{<http://www.w3.org/People/Berners-Lee/card#i> ?p ?o }
         union
       {?s ?o <http://www.w3.org/People/Berners-Lee/card#i>}
      }

Query2:

select distinct ?s ?p ?o
where {{<http://dbpedia.org/resource/Tim_Berners-Lee> ?p ?o }
         union
       {?s ?o <http://dbpedia.org/resource/Tim_Berners-Lee>}
      }


If the SPARQL Processor supports inferencing then Queries 1 & 2 should 
produce identical results (Triples) for the Graph URI: 
http://www.w3.org/People/Berners-Lee/card#i 

-- 


Regards,

Kingsley Idehen	      Weblog: http://www.openlinksw.com/blog/~kidehen
President & CEO 
OpenLink Software     Web: http://www.openlinksw.com
Received on Sunday, 8 July 2007 03:57:34 GMT

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