Re: DAML and Dublin Core: incompatibility?

From: Ian Horrocks (
Date: 03/03/01

On March 3, Dan Brickley writes:
> On Sat, 3 Mar 2001, Ian Horrocks wrote:
> > On March 2, Dan Connolly writes:
> > > Dan Brickley wrote:
> > > > This is a followup to some hallway and lunchtable conversations about
> > > > DAML datatyping and the work of the Dublin Core Metadata Initiative.
> > > >
> > > > My understanding of the forthcoming revision of DAML+OIL+DT(*) is that
> > > > we say all properties are either of the kind that point to resources, or
> > > > of the kind that point to concrete datatypes, strings structured as per
> > > > XML Schema part 2.
> > > 
> > > I don't think that's quite right; I'm not confident I know where
> > > the latest draft is, but my understanding is: DAML+OIL+DT doesn't
> > > say that all properties are either black or white; it just doesn't
> > > tell you the semantics of the grey ones.
> > 
> > This is exactly the case: DAML+OIL+DT defines two subclasses of
> > Property, AbstractProperty and DatatypeProperty.
> So I can re-assure the DC folks that DAML processors won't be throwing
> exceptions or refusing to load DC-based data structures because of this?

Well, we obviously can't guarantee what attitude any given DAML+OIL
processor will take to arbitrary RDF, but there is no reason for it to
barf - it could just ignore those RDF triples to which DAML+OIL does
not assign any semantics.

> (context: this thread was occasioned by a lunchtable remark from TimBL
> along lines that "I'm not sure DC will survive DAML"...).
> An alternate strategy for the 'grey ones' is to wait for RDF-logic rules
> machinery to annotate things like dc:creator with conclusions that can
> be drawn in different contexts. So while the basic definition of
> dc:creator is very loose and grey, additional claims made by DCMI might
> say things like: when dc:creator points to a literal, it is the name of
> an un-named resource of type dc2:Agent. While I'm not sure this is the
> best route for DC, it makes sense given the history: we adopted this
> loose modelling stratgy for DC because RDFS barely existed when DC
> wanted to define a representation in the RDF model.
I agree with Dan C. that this style of modelling is "broken".


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