Behavior Consistent Inheritance in UML

Object-oriented design methods express the behavior an object exhibits over time, i.e., the object life cycle, by notations based on Petri nets or state charts. The paper considers the specialization of life cycles via inheritance relationships as a combination of extension and refinement, viewed in the context of UML state machines. Extension corresponds to the addition of states and actions, refinement refers to the decomposition of states into substates. We use the notions of observation consistency and invocation consistency to compare the behavior of object life cycles and present a set of rules to check for behavior consistency of UML state machines, based on a one-to-one mapping of a meaningful subset of state machines to Object/Behavior Diagrams.