But: OWL is hard!

• The combination of class constructions with various restrictions is extremely powerful

• What we have so far is following the same logic as before

• • extend the basic RDF and RDFS possibilities with new features
  • expect to infer new relationships based on those

• However… a full inference procedure is hard

• • not implementable with simple rule engines, for example
  • in some cases, it may even be impossible