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Re: bnodeification

From: Pat Hayes <phayes@ihmc.us>
Date: Thu, 12 Jan 2006 10:14:21 -0600
Message-Id: <p06230902bfec2f69bc35@[]>
To: Enrico Franconi <franconi@inf.unibz.it>
Cc: tessaris <tessaris@inf.unibz.it>, Bijan Parsia <bparsia@isr.umd.edu>, souripriya.das@oracle.com, public-rdf-dawg@w3.org

>Hi Pat,
>Sergio will send shortly a deep explanation on the list.
>We don't like your solution (a) because it does not work with any 
>ontology language above RDFS that has implicit existentials (like 
>OWL-Lite and above, DLP, or any fragment of FOL with existential 

It works for any ND proof theory for FOL because of the Craig 
interpolation lemma. I think it works for all of these if we relax 
the bnode-binding condition slightly, and IMO reasonably, for these 
more expressive languages where existential generalization is 
proof-theoretically trivial, and given that we have bnodes themselves 
as possible bindings. In the limit, we can allow bnodes to be 'bound' 
to themselves.

>and (b) because the introduction of the scoping graph breaks the 
>subsequent algebra when multiple basic graph patterns are involved 
>(e.g., UNION).

No, it only requires that the scoping graph be used properly. See my 
reply to Sergio.

>  BTW, we already found and discarded a similar solution long time ago :-)

Im not surprised you found it, it is rather obvious once one stops 
being dazzled by the syntactic difference between variables and 
bnodes :-) Its obviouslness is why it is so simple and clear, which 
is why I like it.



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Received on Thursday, 12 January 2006 16:14:38 UTC

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