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Re: RDF* semantics

From: Kingsley Idehen <kidehen@openlinksw.com>
Date: Fri, 30 Aug 2019 16:09:06 -0400
To: public-rdf-star@w3.org
Message-ID: <91ac8f80-6083-88b7-913a-45d8de9dc6bb@openlinksw.com>
On 8/30/19 3:19 PM, Olaf Hartig wrote:
> Thomas,
>
> On fredag 30 augusti 2019 kl. 19:03:16 CEST thomas lörtsch wrote:
>> Am 30. August 2019 14:04:32 MESZ schrieb Olaf Hartig <olaf.hartig@liu.se>:
>>> [...]
>>>
>>> <http://example.org/Alice>  rdf:type  foaf:Person .
>>> <http://example.org/Alice>  foaf:name  "Alice" .
>>> <http://example.org/Alice>  :claims  <http://example.org/Bob> .
>>> <http://example.org/Bob>  rdf:type  foaf:Person .
>>> <http://example.org/Bob>  foaf:name  "Bob" .
>>> <http://example.org/Bob>  foaf:age "23"^^xsd:integer .
>>>
>>> Perhaps now it becomes more apparent that, according to this data,
>>> person Alice claims the person Bob (who is of age 23). This is
>>> different than saying that person Alice makes the following claim:
>>> the thing denoted by IRI is a person named Bob who is of age 23.
>> No, it's the same.
> To me it's not the same.
>
>> The situation may change when you want to describe
>> Alice's claiming activity. Claiming something as such is no different from
>> liking, being located in etc. You wouldn't insist on putting the objects of
>> such statements in parentheses. Something like
>>
>>     ex:Alice ex:likes [ a foaf:Person; foaf:name "Bob" ]
>>
>> would be perfectly alright, wouldn't it?
> Assuming that the IRI ex:Alice is supposed to denote a person named Alice, 
> then the natural interpretation of these example triples (at least for me) 
> would be the following: Person Alice likes a person named Bob. Again, for me 
> that's different from saying: Person Alice likes that there exists a person 
> named Bob.
>
> Olaf
>  
>

You are correct, but explaining in plain English prose doesn't deliver
your core intuition without loss.

SPARQL is a better tool for this task.

Query:

PREFIX : <urn:records:test#>
SELECT DISTINCT *
FROM <urn:records:test>
WHERE { :Alice :likes [ a foaf:Person; foaf:name "Bob" ] }
OFFSET 0
LIMIT 5

Query Result
<http://linkeddata.uriburner.com/sparql?default-graph-uri=&query=PREFIX+%3A+%3Curn%3Arecords%3Atest%23%3E%0D%0ASELECT+DISTINCT+*+%0D%0AFROM+%3Curn%3Arecords%3Atest%3E+%0D%0AWHERE+%7B+%3AAlice+%3Alikes+%5B+a+foaf%3APerson%3B+foaf%3Aname+%22Bob%22+%5D+%7D%0D%0AOFFSET+0%0D%0ALIMIT+5&should-sponge=&format=text%2Fhtml&CXML_redir_for_subjs=121&CXML_redir_for_hrefs=&timeout=30000000> 
-- shows that :Alice likes an indefinite pronoun at best .


Revised Query :

PREFIX : <urn:records:test#>
SELECT DISTINCT *
FROM <urn:records:test>
WHERE { :Alice :likes [ a foaf:Person; foaf:name ?o ] }
OFFSET 0
LIMIT 5

Query Result <http://linkeddata.uriburner.com/sparql?default-graph-uri=&query=PREFIX+%3A+%3Curn%3Arecords%3Atest%23%3E%0D%0ASELECT+DISTINCT+*+%0D%0AFROM+%3Curn%3Arecords%3Atest%3E+%0D%0AWHERE+%7B+%3AAlice+%3Alikes+%5B+a+foaf%3APerson%3B+foaf%3Aname+%3Fo+%5D+%7D%0D%0AOFFSET+0%0D%0ALIMIT+5&should-sponge=&format=text%2Fhtml&CXML_redir_for_subjs=121&CXML_redir_for_hrefs=&timeout=30000000> -- shows "Bob" 


I hope this helps :)

-- 
Regards,

Kingsley Idehen	      
Founder & CEO 
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Received on Friday, 30 August 2019 20:09:32 UTC

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