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Re: Using RDB for a large OWL-DL database.

From: Sören Auer <auer@informatik.uni-leipzig.de>
Date: Thu, 28 Sep 2006 10:58:27 -0400
Message-ID: <451BE313.40909@informatik.uni-leipzig.de>
To: Bijan Parsia <bparsia@isr.umd.edu>, public-owl-dev@w3.org

Bijan Parsia wrote:
> Just out of curiosity, what fragment of OWL does your translation 
> handle? I believe LUMB turns out to be in hornSHIQ:

Good question. I'm not able to say that in two words.
The algorithm first makes some subsumption inferences (currently on the 
basis of explicit subClassOf, oneOf, intersectionOf and unionOf 
Classification is done with regard to almost all OWL axioms and 
descriptions, by generating a DB view for each description/axiom on a 
triple table and combining these views as needed. In case of mutual 
recursion, there is currently some approximation used for computation of 
an initial class extend, which is refined by a second run. We didn't use 
some fix point algorithm due to performance reasons and for many 
practical scenarios this doesn't seem to be needed.
Non-unique names assumption turns out to be problematic, OWLDB does not 
check if certain individuals are the same. But I guess that won't be 
very problematic, when an individual is listed twice (for 
classes/properties of course it's a bigger deal).
I think it's a bit hard to compare the OWLDB approach to classic DL 
reasoners, since only subsumption and classification are supported, both 
with a different set of (in some cases only partially) supported OWL 
Let me know if you want to have a glance at the paper I'm currently 
writing once I have a first draft (might take 2-3 more weeks).


Received on Thursday, 28 September 2006 14:58:59 UTC

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