Learning expressive ontologies 1. Introduction I. Foundations 2. Overview 3. Ontologies 4. Ontology Evaluation 5. Ontology Learning 6. Basic Methods II. Methods for Learning Expressive Ontologies 7. Learning Class Descriptions 8. Learning Property Restrictions 9. Learning Disjointness Axioms 10. Formal Consistency 11. Summary III. Applications and Evaluation 12. Handling Logical Inconsistency 13. Ontology Alignment 14. Towards Semi automatic Ontology Engineering 15. Summary IV. Conclusion 16. Summary 17. Outlook 18. Conclusion