text: **Exercise 21: Convert CheesyPizza from a Primitive Class to a Defined Class**
  
  __ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ___
  
  1. Make sure CheesyPizza is selected. 
  
  2. Select the menu option: Edit>Convert to defined class. 
  
  3. Synchronize the reasoner. 
  
  __ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ___
  
  Your screen should now look similar to figure 4.21. Note that when a class is a defined class it is shown 
  in the UI with three horizontal stripes in the circle next to its name. 
  
  So far we have seen the reasoner do simple things such as propagate disjoint axioms from super classes 
  down to subclasses. However, the reasoner is capable of doing much more. Now that we have a defined 
  class we can see an example of this. Notice that there are two tabs in the Class hierarchy view. The one 
  shown in figure 4.21 is the asserted hierarchy. This is the hierarchy as defined by user declared axioms. 
  The other tab is the Class hierarchy (inferred) tab. This is the hierarchy as inferred by the reasoner. Up 
  until we created a defined class the two tabs would be identical because we had only primitive classes in 
  the ontology. Now that we have a defined class the inferred hierarchy will look different. Select the Class 
  hierarchy (inferred) tab. Make sure that the reasoner is synchronized (it should say Reasoner active as in 
  figure 4.21). Also, make sure to expand the CheesyPizza class in this tab. You should see a screen 
  similar to figure 4.22. As you should see in the inferred tab the reasoner has inferred that all the Pizza 
  classes with a cheese topping are subclasses of CheesyPizza. 