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The third type of relationship that we saw, is

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Generalization. Generalization is a relationship, between a general class,

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which we normally call super-class and the more specific

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class, a class the refines the super-class and that

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we normally call sub-class. It's also known as a

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kind of or is a relationship because we can

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say that the subclass is a super class and

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it's expressed with a solid line with a big arrow

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head at the end. So let's see an example of

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that. In this case I'm going to indicate. Two of this kind

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of relationships. The first one involving the RegistrationUser and

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a student. And the second one, a RegistrationUser and the

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professor. So, basically what we're showing here is a

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typical case in which the registration user is a more general

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concept then the Student and the Professor. So both the student

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and the professor are RegistrationUsers. So there is a relationship,

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the Professor is a registration user and the Student is a RegistrationUser.

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And therefore we can indicate that using

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the generalization relationship in our class diagram.