Andrea Turrini

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We consider bisimulation and weak bisimulation relations in the context of the Labeled Markov Chains of Hans-son and Jonsson, the Concurrent Labeled Markov Chains of Philippou, Lee, and Sokolsky, and the Probabilistic Au-tomata of Segala. We identify a taxonomy of bisimulation relations that captures the existing definitions for each one of the three(More)
We introduce the web-based model checker ISCASMC for probabilistic systems (see http://iscasmc.ios.ac.cn/IscasMC). This Java application offers an easy-to-use web interface for the evaluation of Markov chains and decision processes against PCTL and PCTL * specifications. Compared to PRISM or MRMC, ISCASMC is particularly efficient in evaluating the(More)
Deciding in an efficient way weak probabilistic bisimulation in the context of probabilistic au-tomata is an open problem for about a decade. In this work we close this problem by proposing a procedure that checks in polynomial time the existence of a weak combined transition satisfying the step condition of the bisimulation. This enables us to arrive at a(More)
We study simulation relations for Probabilistic Automata that require transitions to be matched up to negligible sets provided that computation lengths are polynomially bounded. These relations are meant to provide rigorous grounds to parts of correctness proofs for cryptographic protocols that are usually carried out by semi-formal arguments. We illustrate(More)
One of the prevailing ideas in applied concurrency theory and verification is the concept of automata minimization with respect to strong or weak bisimilarity. The minimal automata can be seen as canonical representations of the behaviour modulo the bisimilarity considered. Together with congruence results wrt. process algebraic operators, this can be(More)
Probabilistic automata (PA) are a prominent compositional concur-rency model. As a way to justify property-preserving abstractions, in the last years, bisimulation relations over probability distributions have been proposed both in the strong and the weak setting. Different to the usual bisimulation relations , which are defined over states, an algorithmic(More)
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Probabilistic automata constitute a versatile and elegant model for concurrent probabilistic systems. They are equipped with a compositional theory supporting abstraction, enabled by weak probabilistic bisimulation serving as the reference notion for summarising the effect of abstraction. This paper considers probabilistic automata augmented with costs. It(More)
Weak probabilistic bisimulation on probabilistic automata can be decided by an algorithm that needs to check a polynomial number of linear programming problems encoding weak transitions. It is hence polynomial, but not guaranteed to be strongly polynomial. In this paper we show that for polynomial rational proba-bilistic automata strong polynomial(More)