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Re: properties of properties and DL reasoners

From: Jeremy Carroll <jjc@hpl.hp.com>
Date: Wed, 14 May 2008 19:24:50 +0100
Message-ID: <482B2E72.60407@hpl.hp.com>
To: Evren Sirin <evren@clarkparsia.com>
CC: public-owl-dev@w3.org

Sorry for the delayed reply.

the linked paper is interesting,
and then I am thinking I asked the wrong question ...

If I read about Pellet at say:
I find features such as

Computes the subclass relations between every named class to create the 
complete class hierarchy. The class hierarchy can be used to answer 
queries such as getting all or only the direct subclasses of a class.


Finds the most specific classes that an individual belongs to; i.e., 
realization computes the direct types for each of the individuals. 
Realization can only be performed after classification since direct 
types are defined with respect to a class hierarchy. Using the 
classification hierarchy, it is also possible to get all the types for 
each individual.
that correspond to say the if-and-only-if conditions on rdfs:subClassOf.
& Pellet, when doing these tasks, at some abstract level, spontaneously 
generates/finds these relationships.

At least abstractly we could do a "Propertification" that arranges the 
properties in their hierarchy too, by for every pair p,q of properties 
asking Pellet if an ontology O entails (p subPropertyOf q), and this 
could be, in principle, annotated with inverseOf links, and Functional, 
IFP, Symmetric, Transitive labels ...

It doesn't feel useful though!


Evren Sirin wrote:
> On 5/6/08 7:23 AM, Jeremy Carroll wrote:
>> I've being looking in depth at the OWL 1 Full semantics (again, sigh) ...
>> I note that the classes of properties (FP,IFP, SP, TP) and the 
>> inverseOf property all have iff definitions. These correspond to the 
>> conditions in the direct semantics.
>> Is it the case that DL reasoners can actually answer entailment 
>> questions depending on this e.g.
>> If C is a class consisting of a singleton, and p is a property with 
>> domain and range C, then we necessarily have that p is in FP, IFP, SP 
>> and TP and that p is its own inverse.
>> Moreover if q also has domain and range p, and both q and p are non 
>> empty then they are equivalentProperties, and also each others inverse.
>> Do DL reasoners answer these sorts of question?
> Yes, DL reasoners can answer such entailment queries. Any OWL entailment 
> query can be reduced to an unsatisfiability check in DL reasoning as 
> shown in [1]. Pellet supports these kind of queries. For example, browse 
> a similar ontology [2] in OwlSight [3] and the inferences for the 
> property will be listed (in this example only symmetry and functionality 
> is inferred from asserted axioms).
> Cheers,
> Evren
> [1] http://www.comlab.ox.ac.uk/people/ian.horrocks/Publications/#HoPa04b
> [2] http://www.w3.org/2002/03owlt/SymmetricProperty/premises002.rdf
> [3] 
> http://pellet.owldl.com/owlsight/?ontology=http://www.w3.org/2002/03owlt/SymmetricProperty/premises002.rdf 
>> Ta
>> Jeremy
Received on Wednesday, 14 May 2008 18:26:24 UTC

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