An Abstract Framework for Deadlock Prevention in BIP

Part 6: Session 5: Model CheckingInternational audienceWe present a sound but incomplete criterion for checking deadlock freedom of finite state systems expressed in BIP: a component-based framework for the construction of complex distributed systems. Since deciding deadlock-freedom for finite-state concurrent systems is PSPACE-complete, our criterion gives up completeness in return for tractability of evaluation. Our criterion can be evaluated by model-checking subsystems of the overall large system. The size of these subsystems depends only on the local topology of direct interaction between components, and not on the number of components in the overall system. We present two experiments, in which our method compares favorably with existing approaches. For example, in verifying deadlock freedom of dining philosphers, our method shows linear increase in computation time with the number of philosophers, whereas other methods (even those that use abstraction) show super-linear increase, due to state-explosion

A General Approach to Deadlock Freedom Verification for Software Architectures

none2noWhen building complex software systems, the designer is faced with the problem of detecting mismatches arising from the activity of assembling components. The adoption of formal methods becomes unavoidable in order to support a precise identification of such mismatches in the early design stages. As far as deadlock freedom is concerned, some techniques appeared in the literature, which apply to formal specifications of software architectures under some constraints. In this paper we develop a novel technique for deadlock freedom verification that can be applied to arbitrary software architectures, thus overcoming the limitations of the previous techniques.mixedAldini, Alessandro; Bernardo, MarcoAldini, Alessandro; Bernardo, Marc

Interaction in Concurrent Systems

This dissertation is concerned with the theoretical analysis of component-based models for concurrent systems. We focus on interaction systems, which were introduced by Sifakis et al. in 2003. Centered around interaction systems, we also cover Minsky machines, Petri nets and the Linda calculus and establish relations between the models by giving translations from one to the other. Thus, we gain an insight concerning the expressiveness of the models and learn, given a system described in one syntax, how to simulate it in another. Additionally, these translations allow us to deduce complexity and undecidability results. Namely, we show that the questions whether a LinCa process terminates or diverges under a maximum progress semantics are undecidable. We also prove that the problems of reachability, progress, local and global deadlock and availability are PSPACE-complete in interaction systems. This complexity-theoretic classification serves as a motivation for the sufficient condition approach that is presented in the second half of this work: We present a generic approach to prove properties for component-based systems that allow for decomposition into subsystems. To avoid the problem of state space explosion, we consider overlapping projections and thus compute over-approximations of the reachable global state space. We enhance the quality of these over-approximations by a technique we call Cross-Checking. Based on the enhanced over-approximations, we may then prove properties of the global system in polynomial time. We demonstrate our ideas by means of interaction systems and for the property of local deadlock