From: Pascal Hitzler <hitzler@aifb.uni-karlsruhe.de>

Date: Wed, 15 Nov 2006 05:55:19 +0100

Message-ID: <455A9DB7.3080807@aifb.uni-karlsruhe.de>

To: Hassan Aït-Kaci <hak@ilog.com>

CC: W3C RIF WG <public-rif-wg@w3.org>, Markus Kroetzsch <mak@aifb.uni-karlsruhe.de>, Sebastian Rudolph <sru@aifb.uni-karlsruhe.de>, Michael Sintek <sintek@dfki.uni-kl.de>

Date: Wed, 15 Nov 2006 05:55:19 +0100

Message-ID: <455A9DB7.3080807@aifb.uni-karlsruhe.de>

To: Hassan Aït-Kaci <hak@ilog.com>

CC: W3C RIF WG <public-rif-wg@w3.org>, Markus Kroetzsch <mak@aifb.uni-karlsruhe.de>, Sebastian Rudolph <sru@aifb.uni-karlsruhe.de>, Michael Sintek <sintek@dfki.uni-kl.de>

Let me make a very simple example. Say you have three OWL (more precisely Horn-SHIQ) statements: C \sqcap D \equiv \bot (i.e. C,D are disjoint) B \sqsubseteq C (i.e. B is a subclass of C) and the ABox statement a\in B (i.e. individual a is a member of B). Then this could be translated into logic programming as inc <- C(x), D(x) C(x) <- B(x) B(a) [I'm not sure the KAON2 algorithms would yield exactly this, but it serves as an intuitive example] For the derivation of positive ground facts, like C(a) in this example, the first rule (integrity constraint) can be ignored. If, however, the original knowledge base is inconsistent, e.g. by also containing a\in D, then we would have another fact D(a) in the logic program, which means that ?- inc. would be derivable, showing the inconsistency. Basically, the integrity constraints derived from Horn-SHIQ using the KAON2 algorithms can be ignored, if the original knowledge base is consistent - because they will never fire. Note that this only works for Horn-SHIQ, which is a superset of DLP. It won't work for larger fragments of OWL DL in general. The paper is here: http://www.aifb.uni-karlsruhe.de/WBS/phi/resources/publications/owlvialp06.pdf It also contains the (extensive) example I showed on one of the slides (page 8 top). Best Regards, Pascal. Hassan Aït-Kaci schrieb: > Hi Pascal, > > I mentioned to the RIF WG your 'inc' predicate that you use for > capturing DL features such as class mutual exclusion and negation > in general. From what I understood in your answer to my question > (How the inconsistent predicate 'inc' is used by the interpret of > the LP translation?), you said that it was ignored, and therefore > such inconsistensies were tolerated in the translation. > > The WG wishes to have examples for such things as ignoring features > (such as negation). Can you provied yours as one? > > Thanks. > > -hak -- Dr. habil. Pascal Hitzler Institute AIFB, University of Karlsruhe, 76128 Karlsruhe email: hitzler@aifb.uni-karlsruhe.de fax: +49 721 608 6580 web: http://www.pascal-hitzler.de phone: +49 721 608 4751 http://www.neural-symbolic.orgReceived on Wednesday, 15 November 2006 05:17:58 UTC

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