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   Re: [xml-dev] XML-based Automation (Was: Zen or Games?)

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[Danny Ayers]
> >
> > [Danny Ayers]
> > > ...
> > > CGs and RDF have a lot in common. Taking the main points of the
> > > 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) :
> > >
> > > 6.3 Conceptual Relation - Statement (/Property)
> >
> > Disagree.  "In a conceptual graph, the boxes are called concepts, and
> > circles are called conceptual relations." (Sowa 2000, p476).  RDF has no
> > conceptual relations.  They have to be simulated, most likely with
> Hmm, I would have thought that most of the time CG conceptual relations
> would have mapped directly to RDF properties :

In general, CG conceptual relations are n-ary, not binary.  Simulating an
relation with valence of 5, say, by using a bnode could be done, but there
is no way, even with OWL, so far as I can see, to declare a restriction on
the number and types of predicates that the bnode must have to match the
valence of the CG relation.

> From the CG tutorial [1] :
> A cat is on a mat.
> CG version (approx) :
> [Cat]->-(On)->-[Mat]

From CG examples at     http://users.bestweb.net/~sowa/cg/cgexamp.htm#Ex_4
"A person is between a rock and a hard place}"  - a relation of arity 3
            <-2-[Place]->(Attr)->[Hard].You need to convert the (Betw)
relation to a bnode to simulate this.

> > > 6.7 Referent - Object (of statement)
> >
> > Disagree.  A referent is essential an identifier (Sowa, p 424).
> Ok, I must have misinterpreted that - URIref instead then.
Nope, a referent can have a complex structure (includng wildcards and
variable names).  I suspect that a compex referent would be impractical to
represent by a URI.

> Yep, RDF itself is essentialy just e-c. But it's possible through the use
> RDFS to create terms outside the core, and then give those terms more than
> what's found in base level RDF. e.g. let's have :
> xmldev:not rdfs:subClassOf rdf:Property
> and with a bit of verbal fluff we have negation.

Wrong model - not() is a monadic relation, not binary.  RDF can have no
monadic relations, even with [name your favorite] layered on top.

In RDF it is painful at best to refer to some particular GC-like context (an
arbitrary subgraph), because subgraphs are not identifiable.  You have to
invent something equivalent to rdf:Statement, but more general.  Unpleasant.

Anyway, the degree of extension to RDF needed would be significant.  You
need negation and quantification, at least.


Tom P


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