RE: Expressing "not" in RDF rules

> If    :p :pointsTo :s
> and   :p :pointsTo :t
> and   not(s :pointsTo :t)
> then  :p :hasEdge :t

I'd say that since you're making a statement about a statement, you probably
want to use reify it, i.e.

<rdf:Description>
   <rdf:subject resource="s" />
   <rdf:predicate resource="pointsTo" />
   <rdf:object resource="t"/>
   <rdf:type resource="http://www.w3.org/1999/02/22-rdf-syntax-ns#Statement"
/>
   <a:truthValue>false</a:truthValue>
</rdf:Description>

Not that I've done that myself, mind you :-).

Take a look at the model and syntax spec for more information.  As in all
things, it makes far more sense once you've played with the data structure a
bit (using Jena or one of the Python APIs).

Will.


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