On Mon, Dec 22, 2008 at 10:51:12AM -0800, Karen Coyle wrote:
> On Mon, Dec 22, 2008 at 9:00 AM, Alistair Miles
> <[log in to unmask]> wrote:
>
> > I couldn't find an appropriate property for the "size" of a
> > manifestation in scenario 7.
>
> It's "dimensions" -- that's what I should have written there. Sorry.
Ah, I'll update the RDF.
> > Not directly related to any scenarios, I found that rda:placeOfCapture
> > is a sub-property of rda:placeAndDateOfCapture, which doesn't look
> > right. This looks like a case where Tom Delsey's "sub-elements"
> > pattern got wrongly translated to RDF sub-properties, where rather it
> > should be modelled in RDF as an n-ary relation.
>
> I don't understand 'n-ary', but this is one of those areas where RDA
> has an "empty node" that has parts, like "publication statement" which
> is made up of place + publisher + date. We really didn't know what to
> do with those -- we could ignore the empty element and just include
> the "sub" elements, but we figure that since the empty ones are on the
> RDA list of elements people might look for them in our list. There
> never is a value for placeAndDate... itself, just the sub-elements.
There's a good document on n-ary relations at:
[1] http://www.w3.org/TR/swbp-n-aryRelations/
If you don't want to get into the technicalities, just look at the
pictures, should give a feel for the n-ary relations patterns.
If I were using an n-ary relations pattern for an RDA publication
statement, I would do something like:
ex:M1 rdf:type frbr:Manifestation ;
rda:publicationStatement ex:PS1 .
ex:PS1 rdf:type rda:PublicationStatement ;
rda:placeOfPublication ex:PL1 ;
rda:publisher ex:CB1 ;
rda:dateOfPublication "2008"^^xsd:year ;
.
I.e. the publication statement itself (an n-ary relation) becomes an
entity (resource) with it's own properties.
You could also abbreviate the above, using a blank node for the
publication statement, to something like:
ex:M1 rdf:type frbr:Manifestation ;
rda:publicationStatement [
rda:placeOfPublication ex:PL1 ;
rda:publisher ex:CB1 ;
rda:dateOfPublication "2008"^^xsd:year ;
] ;
.
For the schema, what you need is a class for the n-ary relation
(e.g. rda:PublicationStatement), and a set of properties which give
the various participants in the n-ary relation
(e.g. rda:publicationStatement, rda:placeOfPublication, rda:publisher
etc.). Whether these properties point to or away from the n-ary
relation is a matter of convenience and intuition -- this is
illustrated quite well in the various alternative patterns presented
in [1].
Cheers,
Alistair.
--
Alistair Miles
Senior Computing Officer
Image Bioinformatics Research Group
Department of Zoology
The Tinbergen Building
University of Oxford
South Parks Road
Oxford
OX1 3PS
United Kingdom
Web: http://purl.org/net/aliman
Email: [log in to unmask]
Tel: +44 (0)1865 281993
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