It's a little technical, but I have written a document at http://paulmurraywork.wordpress.com/2010/11/08/it-depends-on-what-you-mean-b...
It demonstrates a method by which properties reified into property objects (such as dwc:ResourceRelationship individuals) can be turned into properties and then reasoned over, and by which the existence of properties can be made dependent on the kinds of things other properties apply to.
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