A person might say that “Fluffy is a cat” and “A cat is a mammal,” and therefore Fluffy should be a subclass of Cat and Cat should be a subclass of Mammal, because we have two is-a relationships. What...

A person might say that “Fluffy is a cat” and “A cat is a mammal,” and therefore Fluffy should be a subclass of Cat and Cat should be a subclass of Mammal, because we have two is-a relationships. What is wrong with this reasoning?