使用protege中的小技巧（续）

• A common error in situations such as above is to only use universal restrictions in descriptions. For example, describing a MargheritaPizza by making it a subclass of Pizza and then only using “hasTopping only （MozzarellaTopping or TomatoTopping）”。However, because of the semantics of the universal restriction, this actually means either: things that are Pizzas and only have toppings that are MozzarellaTopping or TomatoTopping, OR, things that are Pizzas and do not have any toppings at all.所以用全局约束时，还要加上存在约束，比如说要加上hasTopping some MozzarellaTopping ，hasTopping some TomatoTopping约束，表明至少存在的关系。文章中写到如果只用全局约束，then we would have described the set of individuals that only participate in the hasTopping relationship with members of the class Mozzarella, and also those individuals that do not participate in any hasTopping relationships，it probably a mistake.
  
• Automatically create a closure axiom on the hasTopping property for AmericanaPizza，自动创建闭合公理。如hasTopping some TomatoTopping，点击并选择`Create closure axiom'.表示只能被特定的参数所填充的关联关系，此约束有一个参数集，该参数集是所有该关联的存在约束参数的并集。
• 覆盖公理：This covering axiom means that a member of SpicinessValuePartition must be a member of either Mild or Medium or Hot.表现在equivalent class写hot,medium or mild.
• 看类的属性可以在class里的equivalent class里面看到。
• Pizza and hasTopping min 3这是计量约束，约定有最小topping数为3.
• An unqualied cardinality restriction is exactly the same as a qualied cardinality restriction with a filter of Thing. eg. hasTopping min 3 is the same as hasTopping min 3 Thing.
• 大于等于值约束。In the `Class expression editor', type `hasCaloricContentValue some integer[>= 400]' and click `OK'。
• 有hasValue Restrictions。在class中，如MozzarellaTopping hasCountryOfOrigin value Italy.感觉一般是用在枚举类里面的。
• Type {America, England, France, Germany, Italy} into the text box.这是枚举类。
• 大于等于用“greater than or equal to ”,小于等于用“less than or equal to ”在数量描述中。
• intersection class 是用and，而union class是用or。
• 用plugins插件“class matrix”可以方便的一次设置多个some关系，节约时间。