The lack of formal semantics for the UML creates many ambiguity problems, especially when real-time systems are specified. The paper proposes an approach to a formal definition of UML statecharts. Main features of the UML statecharts are described, and next, a transformation of the UML statecharts into LOTOS is defined.
The paper concerns the concept of refinement as a commonly used design practice in the software development process. The refinement relationship is formulated and formally expressed for UML collaborations. Collaborations are suitable for presenting the proposed approach as they represent both static and dynamic aspects of a modeled system or its part, for example, a use case. Our approach to refinement is based on the rule of preserving the observable behavior of a modeled system. The introduced...
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