W3C home > Mailing lists > Public > public-lod@w3.org > March 2010

Re: Conneg representation equivalence

From: Richard Cyganiak <richard@cyganiak.de>
Date: Sun, 21 Mar 2010 14:28:02 +0000
Cc: Vasiliy Faronov <vfaronov@gmail.com>, Linked Data community <public-lod@w3.org>
Message-Id: <D26E94D2-95DA-450D-9FCE-D7A7B5D33796@cyganiak.de>
To: Kingsley Idehen <kidehen@openlinksw.com>
On 21 Mar 2010, at 00:37, Kingsley Idehen wrote:
>> I got the idea of something like this:
>> <http://example.org/>
>> 	a foaf:Document ;
>> 	rdfs:label "Article"@en , "Статья"@ru ;
>> 	dcterms:title "Article"@en , "Статья"@ru ;
>> 	dcterms:creator <http://example.org/id/joe> ;
>> 	dcterms:created "2010-03-04"^^xsd:date ;
>> 	dcterms:hasVersion <http://example.org/index.en.html> ,
>> 		<http://example.org/index.ru.html> .
>> <http://example.org/index.en.html>
>> 	a foaf:Document ;
>> 	rdfs:label "Article"@en ;
>> 	dcterms:title "Article"@en ;
>> 	dcterms:creator <http://example.org/id/joe> ;
>> 	dcterms:created "2010-03-04"^^xsd:date ;
>> 	dcterms:language <http://www.lingvoj.org/lang/en> ;
>> 	dcterms:hasVersion <http://example.org/index.ru.html> .
>> <http://example.org/index.ru.html>
>> 	a foaf:Document ;
>> 	rdfs:label "Статья"@ru ;
>> 	dcterms:title "Статья"@ru ;
>> 	dcterms:creator <http://example.org/id/joe> ;
>> 	dcterms:contributor <http://example.org/id/jane> ;
>> 	dcterms:created "2010-03-17"^^xsd:date ;
>> 	dcterms:language <http://www.lingvoj.org/lang/ru> .
>> Joe is the author of the original article, and he's credited as
>> dcterms:creator. Jane is the translator, she is mentioned as
>> dcterms:contributor for the Russian resource.
> Problem: the Article and the Document (the resource at the URL) are  
> distinct. Think "Book" and "Story in the Book" they are two distinct  
> things with different characteristics (properties) that are  
> connected by a relation.

This is debatable. It rings true in *some* cases (for example, if a  
newspaper article appears both in print and on the web, or indeed  
books). But for text that is only written for the purpose of being  
published on the web, having separate URIs for the “article” and  
the “web document containing the article” is overanalysing.

For example, if I publish a blog post at </blog/2010/03/21/ 
mypost.html>, then it would be overkill to create a separate URI </ 
blog/2010/03/21/mypost.html#this> to distinguish between the “web  
document containing a blog post” and the “blog post as such”. One  
URI (mypost.html) is enough. The only reason for having separate URIs  
would be if the author actually wants to assert different properties  
about the two things, but that doesn't seem likely in the typical web  
publishing case.

(It might be a good idea to mint a URI for the *topic* (or topics) of  
the article, for example if the topic is a person or project or event.  
This allows me to make statements about this person/project/event,  
which clearly has different characteristics than the article, so it  
cannot have the same URI. But that's just a corollary to the old  
linked data axiom that the topic of a document is a different entity  
from the document itself.)


>> dcterms:created for the canonical URI reflects the creation date of  
>> the
>> original article. For the translation, it's substituted with the  
>> date of
>> translation.
>> I'm not sure if we could also say that
>> 	</index.ru.html> dcterms:hasVersion </index.en.html> .
>> I guess it depends on one's reading of the DC spec, probably nobody
>> would die if this triple was included, but here I omitted it for  
>> extra
>> precision.
>> The Lingvoj ontology[1] also has provisions for describing  
>> translations
>> as resources in their own right, but it's a bit beyond the topic  
>> here.
>> As for dcterms:hasFormat, I don't think it can be used here, but if  
>> we
>> also had a PDF version of the article, we could write:
>> 	</index.en.html> dcterms:hasFormat </index.en.pdf> .
>> 	</index.ru.html> dcterms:hasFormat </index.ru.pdf> .
>> (and vice-versa)
>> Further corrections/additions welcome.
>> [1] http://www.lingvoj.org/ontology.rdf
> For simplicity sake, just at "#this" to the following URLs and then  
> reevaluate the model i.e, <http://example.org/index.en.html#this>  
> which is the primary resource (a representation of the document  
> which is basically a container) associated with a secondary resource  
> (a representation of what the document is about). At the current  
> time, your modeling discards the container i.e., treats resource  
> "index.html" as none existent by describing it using properties of  
> its content.
> -- 
> Regards,
> Kingsley Idehen	      President & CEO OpenLink Software     Web: http://www.openlinksw.com
> Weblog: http://www.openlinksw.com/blog/~kidehen
> Twitter/Identi.ca: kidehen
Received on Sunday, 21 March 2010 14:28:38 UTC

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