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Re: SKOS Core review Re: issue: non-Literal "comment" properties Re: new draft of SKOS Core guide

From: Thomas Baker <thomas.baker@bi.fhg.de>
Date: Fri, 25 Feb 2005 16:23:21 +0100
To: Benjamin Nowack <bnowack@appmosphere.com>
Cc: "Miles, AJ (Alistair)" <A.J.Miles@rl.ac.uk>, public-esw-thes@w3.org
Message-ID: <20050225152321.GC2256@Octavius>

Benjamin,

On Fri, Feb 25, 2005 at 03:36:30PM +0100, Benjamin Nowack wrote:
> Just some food for thought:
> 
> I know that it's perfectly legal in non-DL RDFS space to
> have hybrid properties, but given that e.g. dc:creator
> has already caused a lot of confusion and needs rules
> or application-specific extensions to be processed
> without problems, wouldn't it make sense to separate
> datatype props from object props or to limit certain
> documentation props to literals? 

By "hybrid properties", do you mean properties that can
be associated either with literal values or with resources
in themselves?  If so, it is true that this basic tension
has been the cause of much confusion, particularly but not
exclusively with regard to dc:creator.

If so, I can report that in the DCMI context, this problem has
been resolved with the formulation of a DCMI Abstract Model
[1].  The model, which is essentially RDF-compatible but
couched in legacy DCMI terminology, is intended for use as a
point of reference for comparing the expressivity of different
encodings of Dublin Core, such as XHTML, XML and RDF/XML.

The Abstract Model says that the value of a DCMI metadata term
is by definition a resource, even if the representation of
that resource is in some encodings limited to a string value.
The Abstract Model work was itself a response to confusion in
the implementor communities -- confusion that was determined
in large part by the possibilities of different implementation
scenarios.

In the course of untangling these issues, we have ended
up in the DCMI Usage Board with a bias against building
implementation-related restrictions into the very definitions
of the vocabulary.  Limiting values to literals, for example,
can perhaps more appropriately be done in some sort of
application-profile construct rather than "once and for all"
in the canonical representation of the vocabulary.

Tom

[1] http://dublincore.org/documents/abstract-model/

-- 
Dr. Thomas Baker                        Thomas.Baker@izb.fraunhofer.de
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Received on Friday, 25 February 2005 15:20:38 GMT

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