Re: aboutness and broader

Alistair,

as always with issues around logic, the reasoning isn't always  
apparent to the outsider...

I'm not clear about your use of "necessarily", please can you expand  
briefly?

ie what does "mammals have breasts" tell us about animals?
or "carrots are orange" tell us about vegetables?
other than some B can be D? but not necessarily?

and how does that relate to "animals are motile" not telling us about  
mammals?
ie all mammals are motile? is necessarily? though...

cheers

~:"

please excuse my ignorance in this field


Jonathan Chetwynd

j.chetwynd@btinternet.com
http://www.openicon.org/

+44 (0) 20 7978 1764


On 4 Jun 2008, at 10:14, Alistair Miles wrote:

>
> Hi all,
>
> I thought I'd write a quick comment on how "broader" interacts with  
> the
> notion of "aboutness", and how this could be captured formally.
>
> A common view is that, if some concept B is broader than A, then if a
> document D is "about" A, D is necessarily also "about" B.
>
> (E.g. all documents "about" mammals are necessarily also "about"  
> animals.)
>
> To capture this view formally using RDF and OWL, we first need an RDF
> property to represent our notion of "aboutness". For the sake of
> illustration, let's use dc:subject.
>
> We then express a property chain axiom. We say that the property chain
> (dc:subject, skos:broader) is a sub-property of dc:subject.
>
> Now, given this property chain axiom, the graph
>
> <D> dc:subject <A>.
> <A> skos:broader <B>.
>
> entails
>
> <D> dc:subject <B>.
>
> Notice that the property chain axiom causes the dc:subject link to
> "propagate" up the concept hierarchy until it reaches the top. I.e.  
> the
> graph
>
> <D> dc:subject <A>.
> <A> skos:broader <B>.
> <B> skos:broader <C>.
>
> entails
>
> <D> dc:subject <B>, <C>.
>
> Notice also that this behaviour only depends on the property chain  
> axiom. It
> does not require that skos:broader be transitive.
>
> 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.miles@zoo.ox.ac.uk
> Tel: +44 (0)1865 281993
>
>
>
>