Abstract
The lack of formal foundations of UML results in imprecise models since UML only defines graphical notations, but not their formal semantics. However, in safety-critical applications, formal semantics is a requirement for verification. Semantics for the key parts of activities and classes of UML is defined by the semantics of a foundational subset for executable UML models (fUML). Moreover, the base semantics given by fUML defines the formal semantics of UML. In this paper, we evaluate a subset of the base semantics given by fUML covering its formal definition and its use for verification. From the practical perspective, we show with a simple example how the base semantics can support formal verification through theorem proving. The initial results show that the base semantics, when mature, can play an important role in the formal verification of UML models.