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Re: AW: Safe Execution of Recursive Axioms + English

From: Enrico Franconi <franconi@inf.unibz.it>
Date: Tue, 7 Oct 2003 09:52:34 +0200
Message-ID: <005901c38ca7$f867b8c0$47c9010a@unibz.it>
To: "Raphael Volz" <rvo@aifb.uni-karlsruhe.de>
Cc: <www-rdf-logic@w3.org>

From: "Raphael Volz" <rvo@aifb.uni-karlsruhe.de>
> > > I believe that you - generally - can NOT implement OWL Lite
> > > with rule-based reasoners.
> >
> > It is not only a belief, you can formally prove it! No sub-boolean DL
> > (e.g., FL-) with full axioms, and no DL with full booleans (e.g. ALC)
> > without axioms can be ever encoded in a polynomial language (e.g., a
> > rule-based reasoner), as a matter of fact.
> I would like to stay with my belief, you may choose to do some
> preprocessing and compile things and later use your polynomial language
> to do the rest.

I don't get your point. A proof is stronger than a belief :-)

> > > What you seems to be possible
> > > is using Disjunctive Logic Programs, but our proof that an
> > > appropriate translation is indeed correct is not quite finished
> > > yet. Empirically, we pass all tests in the OWL Test Suite and
> > > other well-known DL tests.
> >
> > Still, DLP in its full power is below PSPACE, so again no reasonable DL
> > (with a complexity coming either from full axioms or from the booleans)
> > can be ever be encoded in it. This is the case of OWL-lite which is
> > EXPTIME-hard. So, again, I don't understand what are you really doing.
> >
> Boris Motik is working on the proof, we will see if he can prove it or
> not.

This can't be, unless you are not using disjunctive logic programming.
Did you get my complexity argument? What is your answer to this?
Is there something I am missing? Please let me understand fully your
(and all the proposal which use a rule based approach to reasoning with


Enrico Franconi                  - franconi@inf.unibz.it
Free University of Bozen-Bolzano - http://www.inf.unibz.it/~franconi/
Faculty of Computer Science      - Phone: (+39) 0471-315-642
I-39100 Bozen-Bolzano BZ, Italy  - Fax:   (+39) 0471-315-649
Received on Tuesday, 7 October 2003 03:53:19 UTC

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