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Exercise 4: Create classes: Pizza, PizzaTopping, and PizzaBase 
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1. Navigate to the Entities tab5 with the Class hierarchy view selected.  Make sure owl:Thing is selected.  
2. Press the Add Subclass icon  shown in figure 4.4. This button creates a new subclass of the selected 
class. In this case we want to create a subclass of owl:Thing.   
3. This should bring up a dialog titled Create a new class  with a field for the name of the new class. Type 
in Pizza and then select OK.  
4. Repeat the previous steps to add the classes PizzaTopping and PizzaBase ensuring that 
owl:Thing is selected before using the add subclass icon so that all your classes are subclasses of 
owl:Thing. Your user interface should now look like figure 4.5. Don’t worry that some of the classes 
are highlighted in red. That is because the reasoner hasn’t run yet. We will address this shortly.  
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Figure 4.5 The Classes Sub-Tab in the Entities Tab 
 
5 The Entities tab is a big tab that has tabs like Classes, Object properties, Data properties, etc. as sub-tabs. Each of 
these sub-tabs is also a major tab (a tab accessible from the Window>Tabs option) that can be created on its own. 
Since I took screen snapshots at various times I wasn’t always completely consistent. Sometimes I used Classes as a 
sub-tab of the Entities tab and sometimes as a major tab on its own. Also, at different points in time I had other 
tabs open depending on what other work I was doing. Thus, your UI won’t look identical to the figures. There may 
be additional tabs in the figure that aren’t in your UI or vice versa.