In Protégé, I want to express in OWL the following sentence:
Every person is happy if all his children are successful.
For that reason, I created a class Person, which has a subclass Child.
Now, in the same logic, I would create a class Status and create a subclass Successful. However, another student said that Successful should be an entity (a concept that is?).
What should Successful be, an entity or a class?
We typically refer to entities as an all encompassing concept for classes, individuals and properties. Concept and class are simply synonyms. I assume your classmate meant to say "individual". I personally avoid individuals when writing concept expressions, but in this case, it does not matter whether you use a class or an individual. You need to define a class like HappyPerson = Person and hasChild some (Person and hasStatus some Happy) and hasChild only (Person and hasStatus some Happy). You don't technically need the Child class at all. For a detailed introduction on how to model people and there relationships, see: http://owl.cs.manchester.ac.uk/publications/talks-and-tutorials/fhkbtutorial/