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FW: Mapping between schemas

From: Butler, Mark <mark-h.butler@hp.com>
Date: Tue, 4 May 2004 14:33:08 +0100
Message-ID: <E864E95CB35C1C46B72FEA0626A2E808ED2360@0-mail-br1.hpl.hp.com>
To: SIMILE public list <www-rdf-dspace@w3.org>



-----Original Message-----
From: David R. Karger [mailto:karger@mit.edu] 
Sent: 30 April 2004 18:16
To: Andy_Seaborne@hplb.hpl.hp.com
Cc: Mark_Butler@hplb.hpl.hp.com
Subject: Re: Mapping between schemas



As usual I am much behind, but I wanted to remark on another problem with
defining a "creator" class the way you described it.  Since creator.role
presumably may be different for each work, we can't represent someone who
created multiple resources as a unique resource. This would appear to
complicate our goal of linking?

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   I don't think there is a uniform approach because the original specs
aren't
   uniform in use of a "qualifier".

   Looking at vra3:title:

   vra3:Title.Variant
       could be subProperty of title
       its still a title for the work
   vra3:Title.Translation
       could be subProperty of title
       its still a title for the work

   but

   vra3:Title.Series
      Not a subproperty
      Would seem preferrable to link to the "series" description
   vra3:Title.LargerEntity
      Not a subproperty - this isn't a title for the work

   In Dublin Core there is explicit subProperties:

   dc:created     subPropertyOf  dc:date
   dc:references  subPropertyOf  dc:relation
   dc:medium      subPropertyOf  dc:format

   and if the subProperty is a true statement so is the same pair related by
   the superProperty.

   The var3 mappings to DC also need thinking about 

   vra3:measurements is defined to map to dc:format
     measurements.{dimensions,format,resolution}
   is about the image (actually about the work or about the image)

   vra3:material is defined to dc:format but is about the substance of the
   work.

   so there seems to be confusion between the 

	   Andy


   -----Original Message-----
   From: Butler, Mark [mailto:Mark_Butler@hplb.hpl.hp.com] 
   Sent: 7 October 2003 17:40
   To: www-rdf-dspace@w3.org
   Subject: Mapping between schemas



   Hi team,

   After writing an XSLT transform to turn the Artstor XML into RDF/XML, I
   decided to have a go at writing an RDFS schema for the resulting RDF. I
then
   decided to try to link this schema to an earlier one I had done for VRA
   Core, because the Artstor metadata is based on VRA Core.

   There are a number of problems doing this, but I came across one which I
   want to mention here because I suspect it may be potentially very
generic.
   It is the problem where one schema uses properties whereas another schema
   uses classes.

   For example, consider two schemas that both use the VRA element creator
that
   refers to an image record. Note I am not using RDFS class / property
   terminology here deliberately, because specifications like VRA Core do
not
   use such terms. Creator has a number of qualifiers, e.g. Creator.Role,
   Creator.Attribution, Creator.Personal_name, Creator.Corporate_name. So
how
   do we represent this? Well there are two approaches:

   (a) We can create a property called creator, and then subproperties
called
   role, attribution, personal_name and corporate_name. If we do this, we
are
   making the assumption that an image has exactly one creator.

   (b) Alternatively we can create a class called Creator. Now our Image
   instance has one or more properties called hasCreator, each of which
points
   to an instance of Creator. The properties roles, attribution,
personal_name
   and corporate_name all have domain Creator. Now images can have multiple
   creators, because each creator is an independent object, rather than a
   property value. 

   Now lets consider the mapping:

   1. It's fairly straightforward to map a:role, a:attribution,
a:personal_name
   and a:corporate_name onto their respective counterparts in b.

   2. Mapping b on to a is may be more difficult, if an image does have
   multiple creators.

   3. Mapping between creator is difficult, because it is a property in a
and a
   class in b.

   any thoughts?

   Dr Mark H. Butler
   Research Scientist                HP Labs Bristol
   mark-h_butler@hp.com
   Internet: http://www-uk.hpl.hp.com/people/marbut/
Received on Tuesday, 4 May 2004 09:33:57 EDT

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