4.10.2 Existential Restrictions ............................................................................................................ 31 
4.10.3 Creating Subclasses of Pizza .................................................................................................... 33 
4.10.4 Detecting a Class that can’t Have Members ............................................................................ 37 
4.11 Primitive and Defined Classes (Necessary and Sufficient Axioms) ............................................... 38 
4.12 Universal Restrictions ..................................................................................................................... 41 
4.13 Automated Classification and Open World Reasoning .................................................................. 42