Are UML semantic variances necessary?

I am asking if it is necessary or useful to have semantic variances in UML. Would it not be more useful when it was more formal and therefore verifiable or even used for rapid prototyping. What is the benefit of the varianc开发者_开发技巧e? Can you give some examples?

I would prefer to get rid of the semantic variation points of the UML. A typical example that causes confusion when I model diagrams is the multiple classification semantic variation point. When modeling generalizations in a class diagram, you can choose to assume that the diagram admits multiple classification (an object can be instance of two or more classes not related by a subtype relationship) or not.

Usually designers with a background programming implicitly assume that this is not possible while at the conceptual level many of us tend to implicitly assume that this is possible. You can imagine the result.