Tim Wahls

Executing Formal Specifications with Concurrent Constraint Programming

We have implemented a technique for execution of formal, model-based specifications. The specifications we can execute are written at a level of abstraction that is close to that used in nonexecutable specifications. The specification abstractions supported by our execution technique include using quantified assertions to directly construct post-state values, and indirect definitions of post-state values (definitions that do not use equality). Our approach is based on translating specifications to the concurrent constraint programming language AKL. While there are, of course, expressible assertions that are not executable, our technique is amenable to any formal specification language based on a finite number of intrinsic types and pre- and postcondition assertions.

Formal semantics for SA style data flow diagram specification languages

Using operational semantic techniques, we present a formal semantics for an extended variant of structured analysis style data flow diagrams. This semantics is intended to serve as a semantic foundation for many different specification languages that specify concurrent systems using a graphical notation similar to data flow diagrams. Besides allowing one to specify how information is processed, it allows one to specify the dynamic behavior of a concurrent system. We discuss various semantic issues, including the need for a twostep firing rule and how the semantics supports the notion of refinement.

A graphical user interface for executing formal specifications

In soft w are dev elopmen t, speci cation errors can cause budget overruns or complete failure of dev elopment projects. In an e ort to reduce such risk in softw aredev elopment, formal and model-based speci cation languages ha ve been dev eloped and applied. One such speci cation language is SPECS-C++, which is used to specify C++ classes. A large subset of SPECS-C++ can be executed by translating speci cations to concurrent constrain tprograms. In this w ork, w e describe a graphical user interface that con trols both the translation and the execution of the resulting constrain t programs. This graphical user in terfacepro vides a con venien t tool for constructing test cases, modifying speci cations, and validating original or modi ed speci cations. The interface can be extended to accommodate other speci cation languages, as well as more complex test cases and speci cations.

Formal semantics of an algorithm for translating model-based specifications to concurrent constraint programs

This paper presen tsa denotational semantics for an algorithm for executing formal speci cations. The algorithm executes speci cations written at a high level of abstraction by transforming such speci cations to concurrent constrain t programs. The semantics presen ts the algorithm formally and provides the basis for a soundness proof.