The reason for fUML to be compact is to facilitate the definition of clear semantics. A smaller, more focused subset of UML allows for a more precise and unambiguous specification of the execution semantics.  This clarity is essential for ensuring that models are executed consistently and as intended across different tools and platforms 2 . The compact nature of fUML helps in achieving this goal by limiting the scope to the essential elements necessary for execution, thereby reducing complexity and potential for misinterpretation.

When extending a UML metaclass with a stereotype, it is critical to ensure that the metaclass and the stereotype are semantically related. This is because a stereotype is a way to extend the UML metamodel to create new kinds of model elements that can include additional semantics and constraints, but still adhere to the base behavior defined by the metaclass. The stereotype should be a meaningful specialization of the metaclass and not contradict its fundamental semantics. By keeping them semantically related, there is less need for additional constraints on the metamodel, and the resulting profile is more intuitive for users. This is consistent with the principles described in the UML 2 Specification, particularly in the sections on profiles and stereotypes.

 In the context of the Meta-Object Facility (MOF), a metamodel is essentially a model that defines the structure and semantics of a modeling language. It is a set of constructs and rules that describe how models can be constructed for a particular domain or purpose.  The MOF itself is an example of a metamodel because it provides the language for defining other metamodels, such as the UML metamodel 1 .

In the given diagram, myType1 is shown redefining prop1 , which was originally of type Integer . Given that Integer is a subtype of Number , and myType1 is used in a redefinition context, it implies that myType1 must also be a subtype of Number . In UML, when a property is redefined, the redefining property must be type compatible with the property it redefines. Therefore, myType1 could be substituted by any subtype of Number , which includes Integer , Real , and all their subtypes ( Short , Long , Float , Double , etc.). This is based on the UML principle of type conformance in property redefinition, as specified in the UML 2.x Superstructure Specification.

In UML, a specialized behavior that is an extension or modification of a more general behavior is typically shown using the generalization relationship. Option A correctly models this scenario by showing behavior B as a specialization of behavior A, which is indicated by the containment within the package and a nesting of B inside A without any stereotype on the relationship. This representation implies that B inherits the characteristics of A while potentially adding or overriding some aspects of it.

References:

UML 2.5 Specification : Generalization is defined in the UML 2.5 Specification, where a more specific classifier may override the behaviors of a more general classifier.

In Option C, the properties suitable road surface and average speed have been redefined in the subclasses Recumbent Bike and Racing Bike . The use of the {redefines} keyword in UML signifies that the subclass will provide its own specific values for these properties, overriding the general ones provided by the superclass Bicycle . This is the correct way to enforce that each specialization of Bicycle has a unique set of values for these attributes, as redefinition allows for the customization of inherited properties on a per-subclass basis. The use of {redefines} is specified in the UML 2.x Superstructure Specification, which describes how properties inherited from a superclass can be customized by subclasses.

A FunctionBehavior in UML is a specialized form of behavior that specifies a function that, when executed, yields results influenced only by its input arguments and its internal attributes, without any side effects (e.g., altering global variables or I/O operations). This makes it stateless. Among the options provided:

A involves I/O operations which are not covered under FunctionBehavior as it implies side effects.

B deals with environmental inputs and actuator control, not just function computation.

C could be considered but implies a state change which again might involve side effects, depending on the implementation.

D purely involves calculation based on input parameters, which fits the definition of FunctionBehavior perfectly, as it is a stateless computation.

E is incorrect because UML indeed includes the concept of FunctionBehavior.

References:

UML Specification, Section on Behaviors

Further details on FunctionBehaviors can be found in the UML 2.5 Documentation under the Classification and Behaviors sections.