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The well-known algorithm of Zielonka describes how to transform automatically a sequential automaton into a deterministic asynchronous trace automaton. In this paper, we improve the construction of deterministic asynchronous automata from finite state automaton. Our construction improves the well-known construction in that the size of the asynchronous automaton is simply exponential in both the size of the sequential automaton and the number of processes. In contrast, Zielonka’s algorithm gives an asynchronous automaton that is doubly exponential in the number of processes (and simply exponential in the size of the automaton). [ABSTRACT FROM AUTHOR]

The classical modelization of concurrent system behaviors is based on observing execution sequences of global states. This model is intuitively simple and enjoys a variety of mathematical tools, e.g. finite automata, helping verifying concurrent systems. On the other hand, parallel composition of local controllers are needed when dealing with the actual implementation of concurrent models. A well known tool for turning global observation into local controllers is Zielonka's theorem, and its derivatives. We give here another algorithm, simpler and cheaper than Zielonka's theorem, in the case where the events observed do not include communication but only local asynchronous actions. In a developer point of view, it means that she does not have to explicitly specify the messages needed, which will be added (if allowed) automatically by the implementation algorithm. [ABSTRACT FROM AUTHOR]

The classical model for concurrent systems is based on observing execution sequences of global states, separated from each other by atomic transitions. This model is intuitively simple and enjoys a variety of mathematical tools, e.g., finite automata and linear temporal logic, and algorithms that can be applied in order to test and verify concurrent systems. Although this model is sufficient for most frequently used validation tasks, some phenomena of concurrent systems are difficult to express using its related formalisms. In particular, not all the global states (snapshots) related to an execution appear on a particular execution sequence; some appear on equivalent sequences. Previous attempts to move into formalisms that are based on a more detailed model of execution, e.g,. the causality based model, resulted in specification formalisms with inherently high complexity verification algorithms. We study here verification problems that involve allowing the execution sequences model to observe past global states from equivalent executions. We show various algorithms and complexity results related to our extension of the interleaving model. [ABSTRACT FROM AUTHOR]

Communicating Finite States Machines (CFMs) and Message Sequence Graphs (MSC-graphs for short) are two popular specification formalisms for communicating systems. MSC-graphs capture requirements (scenarios), hence they are the starting point of the design process. Implementing an MSC-graph means obtaining an equivalent deadlock-free CFM, since CFMs correspond to distributed message-passing algorithms. Several partial answers for the implementation have been proposed. E.g., local-choice MSC-graphs form a subclass of deadlock-free CFM: Testing equivalence with some local-choice MSC-graph is thus a partial answer to the implementation problem. Using Compositional MSCs, we propose a new algorithm which captures more implementable models than with MSCs. Furthermore, the size of the implementation is reduced by one exponential. [ABSTRACT FROM AUTHOR]