问题
I was following this tutorial -> LINK
At page 75, it explains how to define a FourCheesePizza using a qualified cardinality restriction. Under the instructions it says "With this description a FourCheesePizza can still also have other relationships to other kinds of toppings. In order for us to say that we just want it to have four cheese toppings and no other toppings we must add the keyword 'only' (the universal quantifier)".
Now, my definition of FourCheesePizza is:
Pizza and hasTopping exactly 4 CheeseTopping
but I don't understand where to add the 'only' keyword, because I only get syntax errors.
回答1:
If you want a four cheese pizza with nothing else than cheese, you have to define it in this way:
Pizza and hasTopping exactly 4 CheeseTopping and hasTopping only CheeseTopping
来源：https://stackoverflow.com/questions/13551280/qualified-cardinality-restriction-definition-in-protege