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> > Probably this particular example for a start. The Conceptual Graph model
> > Sowa uses throughout his work isn't that far removed from the one
> underlying
> > RDF. In fact Tim Berners-Lee [1] and others have considered mappings.
>
> I think it is a long reach to say that RDF is anywhere near close to CGs,
> notwithstanding that you can draw a graph for each.
Apart from being graph-based both RDF and CGs are largely about representing
selected subsets of first order logic. In terms of 'raw power' I think they
can be considered fairly similar - RDF on it's own is pretty feeble, but if
you take into account the stuff (such as OWL) that can be layered on top it
starts to look very powerful indeed. (I'm not really talking of power here
in the logician's expressive power sense, more the coders view of a nice
compromise between expressiveness and tractability).
CGs and RDF have a lot in common. Taking the main points of the abstract
syntax for CGs in the ISO standard [1] it's possible to map across fairly
directly to aspects of RDF (this is a 2 minute, first shot attempt) :
6.1 Conceptual Graph - RDF model
6.2 Concept - Resource
6.3 Conceptual Relation - Statement (/Property)
6.4 Lambda Expression - bnode (maybe)
6.5 Concept Type - Class
6.6 Relation Type - (Property) Class
6.7 Referent - Object (of statement)
6.8 Context - RDF model
6.9 Coreference Set - I don't there's any defined as such in RDF (but I'm
pretty sure it could be)
6.10 Module - RDF model (maybe)
There isn't the same granularity on the RDF side when it comes to graphs and
contexts, but then I think the architecture of RDF makes it easier to
extend/constrain. The triples representation is very handy too. I'm not sure
how straightforward it would be to represent Description Logics using CGs
(IANAL), but my guess is it would be possible.
There are other similarities between CGs and RDF when you look at the
details, as *you* have shown in the past [2] ;-)
Cheers,
Danny.
[1] http://www.jfsowa.com/cg/cgstand.htm#ToC_40
[2]
http://lists.oasis-open.org/archives/topicmaps-comment/200104/msg00085.html
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