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96
A Compositional Specification Theory for Component Behaviours
"... Abstract. We propose a compositional specification theory for reasoning about components that interact by synchronisation of input and output (I/O) actions, in which the specification of a component constrains the temporal ordering of interactions with the environment. Such a theory is motivated by ..."
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Cited by 15 (7 self)
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Abstract. We propose a compositional specification theory for reasoning about components that interact by synchronisation of input and output (I/O) actions, in which the specification of a component constrains the temporal ordering of interactions with the environment. Such a theory is motivated by the need to support composability of components, in addition to modelling environmental assumptions, and reasoning about runtime behaviour. Models can be specified operationally by means of I/O labelled transition systems augmented by an inconsistency predicate on states, or in a purely declarative manner by means of traces. We introduce a refinement preorder that supports safesubstitutivity of components. Our specification theory includes the operations of parallel composition for composing components at runtime, logical conjunction for independent development, and quotient for incremental development. We prove congruence properties of the operations and show correspondence between the operational and declarative frameworks. Keywords: specification theory, compositionality, components, I/O automata, interface automata, logic LTS, refinement, conjunction, quotient.
Quantitative model checking of continuoustime Markov chains against timed automata specification
, 2009
"... We study the following problem: given a continuoustime Markov chain (CTMC) C, and a linear realtime property provided as a deterministic timed automaton (DTA) A, what is the probability of the set of paths of C that are accepted by A (C satisfies A)? It is shown that this set of paths is measurabl ..."
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Cited by 23 (6 self)
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We study the following problem: given a continuoustime Markov chain (CTMC) C, and a linear realtime property provided as a deterministic timed automaton (DTA) A, what is the probability of the set of paths of C that are accepted by A (C satisfies A)? It is shown that this set of paths is measurable and computing its probability can be reduced to computing the reachability probability in a piecewise deterministic Markov process (PDP). The reachability probability is characterized as the least solution of a system of integral equations and is shown to be approximated by solving a system of partial differential equations. For the special case of singleclock DTA, the system of integral equations can be transformed into a system of linear equations where the coefficients are solutions of ordinary differential equations. 1
PRISMgames: A Model Checker for Stochastic MultiPlayer Games
"... Abstract. We present PRISMgames, a model checker for stochastic multiplayer games, which supports modelling, automated verification and strategy synthesis for probabilistic systems with competitive or cooperative behaviour. Models are described in a probabilistic extension of the Reactive Modules ..."
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Cited by 14 (7 self)
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Abstract. We present PRISMgames, a model checker for stochastic multiplayer games, which supports modelling, automated verification and strategy synthesis for probabilistic systems with competitive or cooperative behaviour. Models are described in a probabilistic extension of the Reactive Modules language and properties are expressed using rPATL, which extends the wellknown logic ATL with operators to reason about probabilities, various rewardbased measures, quantitative properties and precise bounds. The tool is based on the probabilistic model checker PRISM, benefiting from its existing user interface and simulator, whilst adding novel model checking algorithms for stochastic games, as well as functionality to synthesise optimal player strategies, explore or export them, and verify other properties under the specified strategy. 1
On the Bisimulation Congruence in χCalculus
"... Abstract. In this paper, we study weak bisimulation congruences for the χcalculus, a symmetric variant of the πcalculus. We distinguish two styles of such bisimulation definitions, i.e. “open ” and “closed ” bisimulation, the difference between which lies in that in open style the equivalence is ..."
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Abstract. In this paper, we study weak bisimulation congruences for the χcalculus, a symmetric variant of the πcalculus. We distinguish two styles of such bisimulation definitions, i.e. “open ” and “closed ” bisimulation, the difference between which lies in that in open style the equivalence is closed under context in every bisimulation step whereas in closed style the equivalence is closed under context only at the very beginning. As a result, we show that both in labelled and barbed congruence, the open and closed style definitions coincide. Thus all bisimulation congruences collapse into two equivalences, that is, the wellknown open congruence and open barbed congruence, which are the same in the strong case, while in the weak case their difference can be reflected by one axiom. The results of this paper close some conjectures in the literatures and shed light on the algebraic theory of a large class of mobile process calculi. 1
On Finite Bases for Weak Semantics:Failures versus Impossible Futures
"... Abstract. We provide a finite basis for the (in)equational theory of the processalgebra BCCS modulo the weak failures preorder and equivalence. We also give positive and negative results regarding the axiomatizability of BCCS moduloweak impossible futures semantics. 1 Introduction Labeled transition ..."
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Abstract. We provide a finite basis for the (in)equational theory of the processalgebra BCCS modulo the weak failures preorder and equivalence. We also give positive and negative results regarding the axiomatizability of BCCS moduloweak impossible futures semantics. 1 Introduction Labeled transition systems constitute a widely used model of concurrent computation.They model processes by explicitly describing their states and their transitions from state to state, together with the actions that produce these transitions. Several notions ofbehavioral semantics have been proposed, with the aim to identify those states that afford the same observations [9, 11]. For equational reasoning about processes, one needsto find an axiomatization that is sound and groundcomplete modulo the semantics under consideration, meaning that all equivalent closed terms can be equated. Ideally,such an axiomatization is also!complete, meaning that all equivalent open terms canbe equated. If such a finite axiomatization exists, it is said that there is a finite basis for
On Finite Bases for Weak Semantics: Failures versus Impossible Futures
"... We provide a finite basis for the (in)equational theory of the process algebra BCCS modulo the weak failures preorder and equivalence. We also give positive and negative results regarding the axiomatizability of BCCS modulo weak impossible futures semantics. ..."
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We provide a finite basis for the (in)equational theory of the process algebra BCCS modulo the weak failures preorder and equivalence. We also give positive and negative results regarding the axiomatizability of BCCS modulo weak impossible futures semantics.
for Component Behaviours?
, 2013
"... Please note that the proofs in this report have not been updated to reflect corrections made to the main body. The proofs should therefore serve as a guide. Readers are advised that the content of this report has largely been superseded by: ..."
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Please note that the proofs in this report have not been updated to reflect corrections made to the main body. The proofs should therefore serve as a guide. Readers are advised that the content of this report has largely been superseded by:
On the axiomatizability of priority
 Proceedings of Automata, Languages and Programming, 33rd International Colloquium, ICALP 2006
, 2006
"... Abstract. This paper studies the equational theory of bisimulation equivalence over the process algebra BCCSP extended with the priority operator of Baeten, Bergstra and Klop. It is proven that, in the presence of an infinite set of actions, bisimulation equivalence has no finite, sound, groundcomp ..."
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Cited by 15 (7 self)
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Abstract. This paper studies the equational theory of bisimulation equivalence over the process algebra BCCSP extended with the priority operator of Baeten, Bergstra and Klop. It is proven that, in the presence of an infinite set of actions, bisimulation equivalence has no finite, sound, groundcomplete equational axiomatization over that language. This negative result applies even if the syntax is extended with an arbitrary collection of auxiliary operators, and motivates the study of axiomatizations using conditional equations. In the presence of an infinite set of actions, it is shown that, in general, bisimulation equivalence has no finite, sound, groundcomplete axiomatization consisting of conditional equations over BCCSP. Sufficient conditions on the priority structure over actions are identified that lead to a finite, groundcomplete axiomatization of bisimulation equivalence using conditional equations. 1
A.: Automatic verification of competitive stochastic systems
, 2011
"... Abstract. We present automatic verification techniques for the modelling and analysis of probabilistic systems that incorporate competitive behaviour. These systems are modelled as turnbased stochastic multiplayer games, in which the players can either collaborate or compete in order to achieve a p ..."
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Cited by 17 (12 self)
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Abstract. We present automatic verification techniques for the modelling and analysis of probabilistic systems that incorporate competitive behaviour. These systems are modelled as turnbased stochastic multiplayer games, in which the players can either collaborate or compete in order to achieve a particular goal. We define a temporal logic called rPATL for expressing quantitative properties of stochastic multiplayer games. This logic allows us to reason about the collective ability of a set of players to achieve a goal relating to the probability of an event’s occurrence or the expected amount of cost/reward accumulated. We give a model checking algorithm for verifying properties expressed in this logic and implement the techniques in a probabilistic model checker, based on the PRISM tool. We demonstrate the applicability and efficiency of our methods by deploying them to analyse and detect potential weaknesses in a variety of large case studies, including algorithms for energy management and collective decision making for autonomous systems. 1
Results 1  10
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