Narciso Martí-Oliet

Maude is a high-performance logical framework based on rewriting logic and supporting formal specification, verification and declarative programming of concurrent systems. Since most concurrent open systems are made up of actor-like objects that communicate with each other through message passing, Maude provides special features to support their specification, verification and programming. Since open systems are heterogeneous, involving widely different kinds of objects such as sensors, actuators, devices, databases, graphical user interfaces, and so on, Maude supports declarative message-passing interaction between Maude objects and a wide variety of heterogeneous external objects. In this paper we explain and illustrate a methodology where an open system can first be designed and verified in Maude and then implemented as a distributed system of heterogeneous objects in a way that seamlessly bridges the gap between its formal specification and verification and its distributed implementation.

In previous work, summarized in this paper, we proposed an operation of parallel composition for rewriting-logic theories, allowing compositional specification of systems and reusability of components. The present paper focuses on compositional verification. We show how the assume/guarantee technique can be transposed to our setting, by giving appropriate definitions of satisfaction based on transition structures and path semantics. We also show that simulation and equational abstraction can be done componentwise. Appropriate concepts of fairness and deadlock for our composition operation are discussed, as they affect satisfaction of temporal formulas. We keep in parallel a distributed and a global view of composed systems. We show that these views are equivalent and interchangeable, which may help our intuition and also has practical uses as, for example, it allows global-style verification of a modularly specified system.

Equational unification and matching are fundamental mechanisms in many automated deduction applications. Supporting them efficiently for as wide as possible a class of equational theories, and in a typed manner supporting type hierarchies, benefits many applications; but this is both challenging and nontrivial. We present Maude 3.2’s efficient support of these features as well as of symbolic reachability analysis of infinite-state concurrent systems based on them.