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From Sean Champ <>
Subject symmetry of class-equivalence relation in OWL
Date Tue, 21 Dec 2010 06:21:21 GMT
Hi folks, just a question:

Given an OWL class A, with A denoted as (the subject) having an equivalent
class B: I've seen that Jena will return B within the return value of
A.listEquivalentClasses(). However - in my experience with using Jena 2.6.3
- the return value of B.listEquivalentClasses() will not contain A, in that
same situation.

My question: Isn't the OWL class-equivalence relation a symmetric relation,

It was my understanding that it was a symmetric relation, but it seems that
Jena is not representing it as so, at that point, in Jena 2.6.3.

I might consider trying to develop a patch, to that ends, myself, but I'm
not sure what the group consensus would be, about it. Simply, it seems to me
that Jena is not currently treating OWL 2 class equivalence as it being a
symmetric relation, given that it does not return A within that call on B,
as above.

Though I can work around that, to produce the desired ends - using a hash
table (one to many) and a method computing all of the equivalent classes of
all classes in a model, and symmetrically storing and returning a map of the
same - but I'm not sure if there may be a more efficient approach to the
same ends, if it would be addressed within Jena itself.


-- Sean

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