Executable Formal Models in Rewriting Logic (Invited Talk)

Formal executable models provide a means to gain insights into the behavior of complex distributed systems. Ideas can be prototyped and assurance gained by carrying out analyses at different levels of fidelity: searching for desirable or undesirable behaviors, determining effects of perturbing the system, and eventually investing effort to carry out formal proofs of key properties. This modeling approach applies to a wide range of systems, including a variety of protocols and networked cyber-physical systems. It is also emerging as an important tool in understanding many different aspects of biological systems. Rewriting logic (RWL) is a formalism that is well-suited to developing and working with formal executable models. In RWL term rewriting is used to represent both structure (equational properties and functions) and transformation / behavior. Logics and inference systems can be naturally represented in RWL, as can the structure and behavior of distributed systems both engineered and natural. Maude is a high performance realization of Rewriting Logic. Maude specifications are naturally executable and the Maude environment provides a variety analysis tools to reason about properties of models. These include reachability analysis, symbolic execution (narrowing), and model-checking. In addition, Maude is reflective. This provides a powerful mechanism for extension. The talk will present a sampling of executable specifications using Maude and its extensions.