Automatic Analysis of Consistency Between Implementations and Requirements

Formal methods like model checking can be used to demonstrate that safety properties of embedded systems are enforced by the system's requirements. Unfortunately, proving these properties provides no guarantee that they will be preserved in an implementation of the system. We have developed a tool, called Analyzer, which helps discover instances of inconsistency and incompleteness in implementations with respect to requirements. Analyzer uses requirements information to automatically generate properties which ensure that required state transitions appear in a model of an implementation. A model is created through abstract interpretation of an implementation annotated with assertions about values of state variables which appear in requirements. Analyzer determines if the model satisfies both automatically-generated and user-specified safety properties. This paper presents a description of our implementation of Analyzer and our experience in applying it to a small but realistic problem. (Also cross-referenced as UMIACS-TR-94-137