Abstract. The paper reports on experiences of mechanizing various proposals for compositional reasoning in concurrent systems. The work uses the UNITY formalism and the Isabelle proof tool. The proposals investigated include existential/universal properties, guarantees properties and progress sets. The results also apply to related proposals such as traditional assumption-commitment guarantees and Misra’s closure properties. Findings that have been published in detail elsewhere are summarised and consolidated here. One conclusion is that UNITY and related formalisms leave some important issues implicit, such as their concept of the program state, which means that great care must be exercised when implementing tool support. Another conclusion is that many compositional reasoning methods can be mechanized, provided that the issues mentioned above are correctly addressed.

We present a graphical environment for parallel object-oriented programming. It provides visual tools to develop and debug object-oriented programs as well as parallel or concurrent systems. This environment was derived from a structural operational semantics of an extension of the Eiffel language, Eiffel//. Object-related features of the language (inheritance, polymorphism) are formalized using a big-step semantics, while the interleaving model of concurrency is expressed with small-step semantics.Without user instrumentation, the interactive environment proposes features such as step-by-step animated executions, graphical visualization of object and process topology, futures and pending requests, control of interleaving, deadlock detection.

This article formally defines Eiffel dynamic binding in presence of renaming and redefinition. Message passing, inheritance, and polymorphism are expressed in an operational style using natural semantics. From the formal specification, we derive an algorithm to determine the appropriate version of a feature to apply to a given object. This algorithm, based only on the class hierarchy and not using any intermediate structure, gives a practical approach to the understanding of inheritance, renaming, and redefinition in Eiffel.