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Re: Modeling change in and between schemes using SKOS - the problem of persistent URIs

From: Danny Ayers <danny.ayers@gmail.com>
Date: Wed, 30 Aug 2006 11:07:50 +0200
Message-ID: <1f2ed5cd0608300207s5145d2fahf082ad3bb3336e35@mail.gmail.com>
To: "Joseph Tennis" <jtennis@interchange.ubc.ca>
Cc: SKOS <public-esw-thes@w3.org>, "Stuart Sutton" <sasutton@u.washington.edu>

(Oops, after typing this I noticed the posts that followed - apologies
if there are points already made I missed)

On 8/28/06, Joseph Tennis <jtennis@interchange.ubc.ca> wrote:

> 1. SKOS postulates a concept exists independent of a scheme
Ok.

> 2. This means that a concept can exist in many schemes (further demonstrated
> by SKOS's inScheme)
Ok.

> 3. However, each scheme delimits the meaning of a concept by its
> relationships with other concepts in the scheme.

Does the scheme do the delimiting, or the set of other concepts?
(which as stated in 1. exist independent of a scheme).

> 4. Change notes, as properties of concepts, are not linked to the scheme in
> which the change applies.

Ok, this seems to be the nub...

> 5. We are left to ask: how do we model scheme specific changes to concepts
> without signaling a new URI?

 - so why is this a problem?

> You can see an illustration of the problem at:
> http://www.ischool.washington.edu/sasutton/skos/Concept_History_New.html

An excellent illustration, although a little more info on the
motivation - the kind of case which leads to this problem - would be
helpful.

> You can also see how we are trying to solve the problem: by introducing an
> ConceptInstance as well as a Concept.  This too can be seen at the above
> URL.


With ConceptInstance it does seem like you're still in effect minting
new Concepts...I'm not entirely clear on why doing this directly would
be a problem.

My naive impression is that this could cause problems later, as it's
modifying (/adding to) the Concept part, when (if I understand
correctly) the problem is actually with the modelling of scheme
changes. This looks like an n-ary relation tying together a specific
scheme, specific change note and (common) concept.

A change note which applied to both to a concept and a scheme might
help, but there's a snag in that changeNote/historyNote are
properties. I wonder if you made a class Note this might help:

Concept
    historyNote
           Note
                associatedWithScheme
                    ConceptScheme


Or maybe you could maybe start from the scheme, with a subclass
AnnotatedScheme which could include a collection of change notes.

Cheers,
Danny.



-- 

http://dannyayers.com
Received on Wednesday, 30 August 2006 09:14:39 GMT

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