This paper presents algorithms for distributed coin tossing. Distributed coin tossing furnishes a symmetrical way to break the symmetry in a distributed system. They allow the conflicts arising from competing remote sites to be overcome in a fair (equiprobable) manner: any site has an equal chance of being selected. It as also shown how these algorithms may be used to obtain a total order between competing sites of a system. Moreover, in each case the outputs of our algorithms are totally unpredictable.>

A testability assessment approach for multicomponent systems is proposed within the framework of formal description techniques. The approach relies on the formal definition of implementation conformance with respect to a given specification. It provides measures of user confidence and guidelines for an automatic design analysis. Both items are based on test requirements. The proposed technique for testability assessment formalizes the common-sense statement that testability of a component is degraded when this component cannot be tested in isolation. Furthermore, it gives a precise answer to the question: What are the limits of a test taking into consideration the constraints of a given environment?.>

This correspondence deals with a unification and extension of some previous work on self-checking (SC) and fail-safe (FS) systems.

An APL simulation is developped in the case of parallel systems which communicate with the environment. This method using interpreted PETRI nets, helps the design verification.