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72
Pamr: A Process Algebra For The Management Of Resources In Concurrent Systems
, 2001
"... In this paper we present a process algebra for the management of resources in concurrent systems. Our aim is to define a formal framework that can help in the task of specifying systems that depend, for their execution, on a set of resources that they use. Usually, systems consist in a set of proces ..."
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Cited by 9 (1 self)
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In this paper we present a process algebra for the management of resources in concurrent systems. Our aim is to define a formal framework that can help in the task of specifying systems that depend, for their execution, on a set of resources that they use. Usually, systems consist in a set of processes. In order to improve their performance, these processes will be able to exchange resources among them. In our language, processes will consist in a behavior (formalized as a LOTOS process) and in information about the resources that they own. Systems will be defined as the parallel composition of a set of processes. We will study some examples applying the features of PAMR. These examples will try to show the usefulness of our language for specifying and analyzing concurrent systems where resources play an important role.
Simulating emergent properties of coordination in maude: the collective sorting case
 in 5th International Workshop on the Foundations of Coordination Languages and Software Architectures
, 2006
"... Recent coordination languages and models are moving towards the application of techniques coming from the research context of complex systems: adaptivity and selforganisation are exploited in order to tackle the openness, dynamism and unpredictability of today’s distributed systems. In this area, s ..."
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Cited by 9 (4 self)
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Recent coordination languages and models are moving towards the application of techniques coming from the research context of complex systems: adaptivity and selforganisation are exploited in order to tackle the openness, dynamism and unpredictability of today’s distributed systems. In this area, systems are to be described using stochastic models, and simulation is considered a valuable tool both for analysis and design. Accordingly, in this work we focus on modelling and simulating emergent properties of coordination techniques. We first describe a framework acting as a generalpurpose engine for simulating stochastic transition system, built as a library for the Maude term rewriting system. We then evaluate this tool to a coordination problem called collective sorting, where autonomous agents move tuples across different tuple spaces according to local criteria, and resulting in the emergence of the complete clustering property.
Ratebased Transition Systems for Stochastic Process Calculi
 AUTOMATA, LANGUAGES AND PROGRAMMING  C. LNCS
, 2009
"... A variant of Rate Transition Systems (RTS), proposed by Klin and Sassone, is introduced and used as the basic model for defining stochastic behaviour of processes. The transition relation used in our variant associates to each process, for each action, the set of possible futures paired with a mea ..."
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Cited by 8 (2 self)
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A variant of Rate Transition Systems (RTS), proposed by Klin and Sassone, is introduced and used as the basic model for defining stochastic behaviour of processes. The transition relation used in our variant associates to each process, for each action, the set of possible futures paired with a measure indicating their rates. We show how RTS can be used for providing the operational semantics of stochastic extensions of three classical formalisms, namely CSP, CCS and picalculus. It is also shown that, in contrast with the original definition by Priami, our semantics for stochastic picalculus guarantees associativity of parallel composition.
The Earlier the Better: A Theory of Timed Actor Interfaces
"... Programming embedded and cyberphysical systems requires attention not only to functional behavior and correctness, but also to nonfunctional aspects and specifically timing and performance constraints. A structured, compositional, modelbased approach based on stepwise refinement and abstraction t ..."
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Cited by 7 (3 self)
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Programming embedded and cyberphysical systems requires attention not only to functional behavior and correctness, but also to nonfunctional aspects and specifically timing and performance constraints. A structured, compositional, modelbased approach based on stepwise refinement and abstraction techniques can support the development process, increase its quality and reduce development time through automation of synthesis, analysis or verification. For this purpose, we introduce in this paper a general theory of timed actor interfaces. Our theory supports a notion of refinement that is based on the principle of worstcase design that permeates the world of performancecritical systems. This is in contrast with the classical behavioral and functional refinements based on restricting or enlarging sets of behaviors. An important feature of our refinement is that it allows timedeterministic abstractions to be made of timenondeterministic systems, improving efficiency and reducing complexity of formal analysis. We also show how our theory relates to, and can be used to reconcile a number of existing time and performance models and how their established theories can be exploited to represent and analyze interface specifications and refinement steps.
Mobility Models and Behavioural Equivalence for Wireless Networks
"... Abstract. In protocol development for wireless systems, the choice of appropriate mobility models describing the movement patterns of devices has long been recognised as a crucial factor for the successful evaluation of protocols. More recently, wireless protocols have also come into the focus of fo ..."
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Abstract. In protocol development for wireless systems, the choice of appropriate mobility models describing the movement patterns of devices has long been recognised as a crucial factor for the successful evaluation of protocols. More recently, wireless protocols have also come into the focus of formal approaches to the modelling and verification of concurrent systems. While in these approaches mobility is also given a central role, the actual mobility modelling remains simplistic since arbitrary node movements are allowed. This leads to a huge behavioural overapproximation that might prevent a successful reasoning about protocol properties. In this paper we describe how to extend a process calculus by realistic mobility models in an orthogonal way. The semantics of our calculus incorporates a notion of global time passing that allows us to express a wide range of mobility models currently used in protocol development practice. Using the behavioural equivalence and preorder of our calculus, we are furthermore able to compare the strength of these models in our approach. 1
Implementing a Model Checker for Performability Behaviour
, 2001
"... We describe a novel model checking algorithm for analysing the behaviour of stochastic systems with respect to their performability. Systems are modelled as actionlabelled CTMCs, and the properties to be veri#ed are speci#ed with the help of the actionbased temporal logic aCSL. ..."
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Cited by 6 (3 self)
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We describe a novel model checking algorithm for analysing the behaviour of stochastic systems with respect to their performability. Systems are modelled as actionlabelled CTMCs, and the properties to be veri#ed are speci#ed with the help of the actionbased temporal logic aCSL.
Specification and Performance of the MPEG2 Video Encoder by Using the Stochastic Process Algebra: ROSA
, 2001
"... In this paper we present the speci cation of the MPEG2 algorithm for video encoding, by using the Stochastic Process Algebra ROSA (Reasoning On Stochastic Algebras). This process algebra is a very general framework for describing and analysing concurrent systems. Thus, we also study the tempor ..."
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Cited by 6 (1 self)
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In this paper we present the speci cation of the MPEG2 algorithm for video encoding, by using the Stochastic Process Algebra ROSA (Reasoning On Stochastic Algebras). This process algebra is a very general framework for describing and analysing concurrent systems. Thus, we also study the temporal behaviour of the algorithm, by using a performance evaluation algorithm, which is also presented in this paper.
Learning Continuous Time Markov Chains from Sample Executions
, 2004
"... Continuoustime Markov Chains (CTMCs) are an important class of stochastic models that have been used to model and analyze a variety of practical systems. In this paper we present an algorithm to learn and synthesize a CTMC model from sample executions of a system. Apart from its theoretical interes ..."
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Cited by 5 (0 self)
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Continuoustime Markov Chains (CTMCs) are an important class of stochastic models that have been used to model and analyze a variety of practical systems. In this paper we present an algorithm to learn and synthesize a CTMC model from sample executions of a system. Apart from its theoretical interest, we expect our algorithm to be useful in verifying blackbox probabilistic systems and in compositionally verifying stochastic components interacting with unknown environments. We have implemented the algorithm and found it to be effective in learning CTMCs underlying practical systems from sample runs.
Trinitis: Simple Models for HighAvailability Systems with Dependent Components
 In: Proceedings of the European Safety and Reliability Conference (ESREL 2006
, 2006
"... ABSTRACT: When modeling faulttolerant systems, statebased methods yield much more realistic results in comparison to traditional combinatorial methods. To avoid the difficult manual design of large statebased models, we advocate an approach, by which a highlevel input model is used from which a ..."
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Cited by 5 (3 self)
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ABSTRACT: When modeling faulttolerant systems, statebased methods yield much more realistic results in comparison to traditional combinatorial methods. To avoid the difficult manual design of large statebased models, we advocate an approach, by which a highlevel input model is used from which a semantically equivalent lowlevel model is automatically generated. This approach was implemented in the tool OpenSESAME (Simple but Extensive Structured Availability Modeling Environment). Its input uses reliability block diagrams as a widespread modeling technique favored by many reliability engineers. In addition, users can specify intercomponent dependencies of the system without having to create a statebased model. The main contributions of this paper are, first, a detailed description of the input model showing the application areas and limitations of OpenSESAME; second, a detailed explanation of the transformation process into the statespace domain; and third, it contains a realistic industrial example modeling a water supply system of a city. 1
M.: Structural operational semantics for continuous state probabilistic processes
 In: Proc. CMCS’12. Lecture Notes in Computer Science
, 2012
"... Abstract. We consider the problem of modeling syntax and semantics of probabilistic processes with continuous states (e.g. with continuous data). Syntax and semantics of these systems can be defined as algebras and coalgebras of suitable endofunctors over Meas, the category of measurable spaces. In ..."
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Cited by 4 (2 self)
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Abstract. We consider the problem of modeling syntax and semantics of probabilistic processes with continuous states (e.g. with continuous data). Syntax and semantics of these systems can be defined as algebras and coalgebras of suitable endofunctors over Meas, the category of measurable spaces. In order to give a more concrete representation for these coalgebras, we present an SOSlike rule format which induces an universal semantics, for which behavioural equivalence is a congruence. To this end, we solve several problems. In particular, the format has to specify how to compose the semantics of processes (which basically are continuous state Markov processes). This is achieved by defining a language of measure terms, i.e., expressions specifically designed for describing probabilistic measures. Thus, the transition relation associates processes with measure terms. As an example application, we model a CCSlike calculus of processes placed in an Euclidean space. The approach we follow in this case can be readily adapted to other quantitative aspects, e.g. Quality of Service, physical and chemical parameters in biological systems, etc. 1