On UML2.0's Abandonment of the Actors-Call-Use-Cases Conjecture

UML2.0 recently made a correction which effectively means that they finally abandoned the ACU conjecture, admitting it was wrong. The ACU conjecture is a fallacious statement that makes people believe that actors call operations of a use case. It originated in OOSE and was implicitly employed by UML. It caused serious defects in UML’s specification of the use-case class. Although the correction itself could shed light on the long-troubled use-case specification, UML2.0 does not recognize its significance. This is proved by the fact that it still retains those defects. The paper states how the ACU conjecture caused them. It then presents a model of a designer’s simulation of a use case, derives a use-case class/object, and specifies its static and dynamic properties. In relation with this, it clarifies the meaning of a use-case diagram that has been left ambiguous.