Alistair Miles
Tue, 23 Dec 2008 08:47:43 -0800
On Mon, Dec 22, 2008 at 10:51:12AM -0800, Karen Coyle wrote: > On Mon, Dec 22, 2008 at 9:00 AM, Alistair Miles > <alistair.mi...@zoo.ox.ac.uk> 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: alistair.mi...@zoo.ox.ac.uk Tel: +44 (0)1865 281993