W3C home > Mailing lists > Public > public-esw-thes@w3.org > May 2005

Re: Confused ... RE: Subject Indicators RE: Using SKOS RDF vocabulary in RDFS

From: Kal Ahmed <kal@techquila.com>
Date: Tue, 03 May 2005 15:00:02 +0100
Message-ID: <427783E2.9060000@techquila.com>
To: "Miles, AJ (Alistair)" <A.J.Miles@rl.ac.uk>
CC: Bernard Vatant <bernard.vatant@mondeca.com>, public-esw-thes@w3.org


Miles, AJ (Alistair) wrote:

>However, there is a problem to consider when mapping from RDF to topic maps.  To illustrate this problem, and to avoid any confusion surrounding existing URI schemes, let us assume that there exists some URI scheme called 'foo:'.  Ownership of parts of this URI space may be obtained by simply applying in writing to the Foo organisation, which then gives you (free of charge) a part of this space corresponding to a unique number.  For example, I applied to Foo inc. and got ownership of the URI space foo:00789:.  So now I am free to coin URIs like foo:00789:bar foo:00789:bar/blah etc. and allocate them to whatever I want.  I have a pet hamster called Gerald, whom I would especially like to be able to make RDF statements about, so I allocate the URI foo:00789:gerald-the-hamster to him.  This scenario is completely consistent with the webarch as I understand it.
>
>So, then, how would I translate the following RDF graph:
>
><rdf:RDF>
>
>	<ex:Hamster rdf:about="foo:001789:gerald-the-hamster">
>		<foaf:name>Gerald</foaf:name>
>	</ex:Hamster>
>
></rdf:RDF>        
>
>... into an XML topic map?  The URI 'foo:001789:gerald-the-hamster' certainly doesn't 'locate' Gerald, so I can't use the xtm:subjectLocator element.  Niether does this URI correspond to a published subject indicator document, so I can't use the xtm:subjectIndicator element.
>
>So isn't it correct to say that Subject identity in topic maps is restricted to the subset of URI space that is URL space, because it depends on subjects being either 'locatable' in themselves, or having a 'locatable' subject indicator document?
>  
>
There is a note in ISO 13250 that says:

"NOTE 18 The information referenced by an identity attribute may or may 
not take the form of a topic link in a topic map
document, may or may not be text, may or may not be 
machine-interpretable, and may or may not be online."

This note is talking about the HyTime constructs, but to map to XTM 
terminology, the "identity attribute" is the subject identifer. In your 
specific example, the identifier foo:001789:gerald-the-hamster is 
dereferenced by asking the creator of the identifier "What is identified 
by foo:001789:gerald-the-hamster". So the referent is not 
machine-interpretable and is not text, but the identifier is still a 
valid subject identifier (as long as the creator is consistent about 
what is identified...but thats an issue for machine-resolvable URI 
identifiers too).

However, I believe that what you assert above is true about *published* 
subject identifiers.

Cheers,

Kal
Received on Tuesday, 3 May 2005 13:48:43 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Monday, 7 December 2009 10:38:53 GMT