when using Rowlex OwlGrinder to generate an assembly from an OWL file the above error message is shown. The offending piece of OWL/XML is for example:
<DisjointClasses>
<Class URI="&foaf;Document"/>
<Class URI="&foaf;Organization"/>
</DisjointClasses>
but the same error message is also thrown in the case of multiple superclasses - e.g.:
<SubClassOf>
<Class URI="&foaf;Image"/>
<Class URI="&wordnet;Document"/>
</SubClassOf>
I am perfectly willing to accomodate my ontologies to a certain extend to be compatible with OwlGrinder, but the above code is happily processed by for example Protege so I assume it is valid OWL. Do you have a suggestion how to approach the - quite vital - information of disjoint-classes/multi-inheritance?
Thank you a lot, Hinnerk
Hmm - sorry for this. Looks like the problem actually was the file format of that Ontology being OWL/XML. When using RDF/XML things worked fine.