Hi Everybody!

I'm currently struggeling with with an ontology that should contain
partOf-Relations. The ontology should be in OWL-DL.

Suppose I have the following classes:

Country
State
City

and the following individuals:

USA (type Country)
California (type State)
LosAngeles (type City)

and there should be a transitive "isPartOf" relation. However I would like
to further constrain the classes City and State to being only part of
exactly one specific State or Country. Therefore I introduced another
property "isDirectPartOf" which is not transitive but functional.

The class definitions now look like this:

 Class(a:City partial 
  restriction(a:directPartOf cardinality(1))
  restriction(a:directPartOf someValuesFrom(a:State)))

 Class(a:State partial 
  restriction(a:directPartOf someValuesFrom(a:Country))
  restriction(a:directPartOf cardinality(1)))

Now my problem is: I'm still interested in the transitive isPartOf
relationship. Is there any way to infer that LosAngeles isPartOf USA ?

I've tried to make both properties equivalent, but I think that wasn't the
right thing. Currently the only option seems to me using a higher order
language like SWRL. But I'd rather like not to, as long as there is any
other way in OWL-DL.

Thanks for your patience,

Tom