Tools for formal specification, verification, and validation of requirements

Although formal methods for developing computer systems have been available for more than a decade, few have had significant impact in practice. A major barrier to their use is that software developers find formal methods difficult to understand and apply. One exception is a formal method called SCR for specifying computer system requirements which, due to its easy to use tabular notation and its demonstrated scalability, has already achieved some success in industry. Recently a set of software tools, including a specification editor, a consistency checker, a simulator, and a verifier has been developed to support the SCR method. This paper describes recent enhancements to the SCR tools: a new dependency graph browser which displays the dependencies among the variables in the specification, an improved consistency checker which produces detailed feedback about detected errors, and an assertion checker which checks application properties during simulation. To illustrate the tool enhancements, a simple automobile cruise control system is presented and analyzed.