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Re: The Steven King Example

From: Ian Davis <ian.davis@talis.com>
Date: Fri, 24 Nov 2006 19:58:03 +0000
Message-ID: <45674ECB.4090904@talis.com>
To: Murray Maloney <murray@muzmo.com>
CC: public-grddl-wg <public-grddl-wg@w3.org>

On 24/11/2006 18:11, Murray Maloney wrote:
> 
> At 04:45 PM 11/24/2006 +0000, Ian Davis wrote:
>> On 24/11/2006 16:20, Murray Maloney wrote:
>>> Dan wrote a GRDDL result that is much more complex than I had hoped,
>>> but he said that it was an accurate RDF representation of the triple:
>>>         "Stephen King" "is author of" "The Stand".
>>> I am totally willing to accept the proposition that Dan and I got it 
>>> wrong. I would love
>>> to see the example that gets it right, and I only hope that I will be 
>>> able to follow it.
>>
>> I would suggest this:
>>
>> <rdf:Description rdf:about="http://example.com/authors#king">
>>   <ex:isAuthorOf rdf:resource="http://example.com/books#stand" />
>> </rdf:Description>
> 
> Bzzzt. Sorry, wrong answer. Thanks for trying.
> 
> Those URIs tell me nothing. Actually, they tell me "Unable to Connect"
> And what is the namespace "ex" and how do I find out the meaning of
> the isAuthorOf property in that namespace?

OK, with a real property:

<rdf:RDF
   xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
   xmlns:f="http://purl.org/vocab/frbr/core#">

   <rdf:Description rdf:about="http://example.com/authors#king">
     <f:creatorOf rdf:resource="http://example.com/books#stand" />
   </rdf:Description>
</rdf:RDF>

You can look http://purl.org/vocab/frbr/core#creatorOf up to get a 
definition. This will tell you that the subject of this triple is q 
f:ResponsibleEntity (which further lookup would tell you is either a 
f:CorporateBody or a foaf:Person) and the object is a f:Work

I don't know of any URIs that represent Stephen King or his book. I know 
of some that represent web pages about those things.

However simply by stating the RDF above I am claiming that 
http://example.com/authors#king represents the creator of the resource 
identified by http://example.com/books#stand which is perfectly valid. 
Just because you can't get representations of those resources from those 
URIs doesn't mean it's broken, inappropriate or invalid.

If I didn't want to assign a URI to each resource then I would use 
indirection. This is where the primary topic stuff in the primer example 
comes from. So, omitting the URI for the subject and using wikipedia as 
an indirect reference (usual namespaces assumed):

   <rdf:Description>
     <foaf:isPrimaryTopicOf 
rdf:resource="http://en.wikipedia.org/wiki/Stephen_King" />
     <f:creatorOf rdf:resource="http://example.com/books#stand" />
   </rdf:Description>

You can look http://xmlns.com/foaf/0.1/isPrimaryTopicOf up to discover 
what that property means (hmmm xmlns.com appears to be unavailable today)

I could use indirection to eliminate the URI for the object. Using some 
details of the frbr model (A Work is realized by an Expression which is 
embodied in a Manifestation which are physical things with ISBNs and 
publishers etce)

   <rdf:Description>
     <foaf:isPrimaryTopicOf 
rdf:resource="http://en.wikipedia.org/wiki/Stephen_King" />
     <f:creatorOf>
       <f:Work>
         <f:realization>
           <f:Expression>
             <f:embodiment>
               <f:Manifestation>
                 <foaf:isPrimaryTopicOf 
rdf:resource="http://www.amazon.com/Stand-Expanded-First-Complete-Signet/dp/0451169530/" 
/>
               </f:Manifestation>
             </f:embodiment>
           </f:Expression>
         </f:realization>
       </f:Work>
     </f:creatorOf>
   </rdf:Description>

Somewhat verbose for the introduction i suspect which is why I suggested 
the very first form.

Ian
Received on Friday, 24 November 2006 20:31:47 GMT

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