Compositional Verification in Supervisory Control.
ABSTRACT This paper proposes a compositional approach to verifying whether a large discrete event system is nonblocking. The new approach avoids computing the synchronous product of a large set of finite-state machines. Instead, the synchronous product is computed gradually, and intermediate results are simplified using conflict-preserving abstractions based on process-algebraic results about fair testing. Heuristics are used to choose between different possible abstractions. By translating the problem representation, the same method can also be applied to verify safety properties, in particular, controllability. Experimental results show that the method is applicable to finite-state machine models of industrial scale and brings considerable improvements in performance over other methods for nonblocking verification.
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ABSTRACT: This paper proposes to enhance compositional verification of the nonblocking property of discrete event systems by introducing annotated automata. Annotations store nondeterministic branching information, which would otherwise be stored in extra states and transitions. This succinct representation makes it easier to simplify automata and enables new efficient means of abstraction, reducing the size of automata to be composed and thus the size of the synchronous product state space encountered in verification. The abstractions proposed are of polynomial complexity, and they have been successfully applied to model check the nonblocking property of the same set of large-scale industrial examples as used in related work.Discrete Event Dynamic Systems 12/2012; 22(4). · 0.71 Impact Factor
Conference Paper: A process-algebraic semantics for generalised nonblocking[Show abstract] [Hide abstract]
ABSTRACT: Generalised nonblocking is a weak liveness property to express the ability of a system to terminate under given preconditions. This paper studies the notions of equivalence and refinement that preserve generalised nonblocking and proposes a semantic model that characterises generalised nonblocking equivalence. The model can be constructed from the transition structure of an automaton, and has a finite representation for every finite-state automaton. It is used to construct a unique automaton representation for all generalised nonblocking equivalent automata. This gives rise to effective decision procedures to verify generalised nonblocking equivalence and refinement, and to a method to simplify automata while preserving generalised nonblocking equivalence. The results of this paper provide for better understanding of nonblocking in a compositional framework, with possible applications in compositional verification.Proceedings of the Seventeenth Computing: The Australasian Theory Symposium - Volume 119; 01/2011
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ABSTRACT: The observer property is an important condition to be satisfied by abstractions of Discrete Event System (DES) models. This technical note presents a new algorithm that tests if an abstraction of a DES obtained through natural projection has the observer property. The procedure, called OP-Verifier, can be applied to (potentially nondeterministic) automata, with no restriction on the existence of cycles of “non-relevant” events. This procedure has quadratic complexity in the number of states. The performance of the algorithm is illustrated by a set of experiments.IEEE Transactions on Automatic Control 08/2014; · 2.72 Impact Factor