Re: Expressiveness of RDF as Rule Conclusion Language (was Re: W hat is an RDF Query? )

 Drew McDermott said:

    Okay, if you change Sandro's "document scope"
    to "graph scope," you're right.  But then a rule like

     (R1 ?x ?y) |-   (R2 ?y ?x)

    becomes unstatable, because the ?x and ?y in
    the graph on the left are different variables from the
    ?x and ?y in the graph on the right.

    Unless I'm missing something.

Well, If I understand RDF graphs, I think you are.  Don't forget every term
(variable or not) has to be a URI in a RDF graph.   But if we scope formulas
to a context (a collection of statements) the ?x ?y in the left hand of the
formula become *the same* as the ?x ?y on the right .... that's the way RDF
works .... doesn't it ?

Please see the RDF mentograph:

http://robustai.net/mentography/entailsIdentity.gif

and my view of identity:
http://robustai.net/ai/identity.htm

Seth Russell