Results 1  10
of
18
Bisimulation for Probabilistic Transition Systems: A Coalgebraic Approach
, 1998
"... . The notion of bisimulation as proposed by Larsen and Skou for discrete probabilistic transition systems is shown to coincide with a coalgebraic definition in the sense of Aczel and Mendler in terms of a set functor. This coalgebraic formulation makes it possible to generalize the concepts to a ..."
Abstract

Cited by 74 (15 self)
 Add to MetaCart
. The notion of bisimulation as proposed by Larsen and Skou for discrete probabilistic transition systems is shown to coincide with a coalgebraic definition in the sense of Aczel and Mendler in terms of a set functor. This coalgebraic formulation makes it possible to generalize the concepts to a continuous setting involving Borel probability measures. Under reasonable conditions, generalized probabilistic bisimilarity can be characterized categorically. Application of the final coalgebra paradigm then yields an internally fully abstract semantical domain with respect to probabilistic bisimulation. Keywords. Bisimulation, probabilistic transition system, coalgebra, ultrametric space, Borel measure, final coalgebra. 1 Introduction For discrete probabilistic transition systems the notion of probabilistic bisimilarity of Larsen and Skou [LS91] is regarded as the basic process equivalence. The definition was given for reactive systems. However, Van Glabbeek, Smolka and Steffen s...
Metrics for Labelled Markov Processes
, 2003
"... The notion of process equivalence of probabilistic processes is sensitive to the exact probabilities of transitions. Thus, a slight change in the transition probabilities will result in two equivalent processes being deemed no longer equivalent. This instability is due to the quantitative nature ..."
Abstract

Cited by 46 (10 self)
 Add to MetaCart
The notion of process equivalence of probabilistic processes is sensitive to the exact probabilities of transitions. Thus, a slight change in the transition probabilities will result in two equivalent processes being deemed no longer equivalent. This instability is due to the quantitative nature of probabilistic processes. In a situation where the process behaviour has a quantitative aspect there should be a more robust approach to process equivalence. This paper studies a metric between labelled Markov processes. This metric has the property that processes are at zero distance if and only if they are bisimilar. The metric is inspired by earlier work on logics for characterizing bisimulation and is related, in spirit, to the Kantorovich metric.
Metrics for Labelled Markov Systems
, 2001
"... The notion of process equivalence of probabilistic processes is sensitive to the exact probabilities of transitions. Thus, a slight change in the transition probabilities will result in two equivalent processes being deemed no longer equivalent. This instability is due to the quantitative nature of ..."
Abstract

Cited by 43 (8 self)
 Add to MetaCart
The notion of process equivalence of probabilistic processes is sensitive to the exact probabilities of transitions. Thus, a slight change in the transition probabilities will result in two equivalent processes being deemed no longer equivalent. This instability is due to the quantitative nature of probabilistic processes. In a situation where the process behaviour has a quantitative aspect there should be a more robust approach to process equivalence. This paper studies a metric between labelled Markov processes. This metric has the property that processes are at zero distance if and only if they are bisimilar. The metric is inspired by earlier work on logics for characterizing bisimulation and is related, in spirit, to the Hutchinson metric.
Domain Equations for Probabilistic Processes
 MATHEMATICAL STRUCTURES IN COMPUTER SCIENCE
, 1997
"... In this paper we consider Milner's calculus CCS enriched by a probabilistic choice operator. The calculus is given operational semantics based on probabilistic transition systems. We define operational notions of preorder and equivalence as probabilistic extensions of the simulation preorder an ..."
Abstract

Cited by 17 (1 self)
 Add to MetaCart
In this paper we consider Milner's calculus CCS enriched by a probabilistic choice operator. The calculus is given operational semantics based on probabilistic transition systems. We define operational notions of preorder and equivalence as probabilistic extensions of the simulation preorder and the bisimulation equivalence respectively. We extend existing categorytheoretic techniques for solving domain equations to the probabilistic case and give two denotational semantics for the calculus. The first, "smooth", semantic model arises as a solution of a domain equation involving the probabilistic powerdomain and solved in the category CONT? of continuous domains. The second model also involves appropriately restricted probabilistic powerdomain, but is constructed in the category C UM of complete ultrametric spaces, and hence is necessarily "discrete". We show that the domaintheoretic semantics is fully abstract with respect to the simulation preorder, and that the metric semantics is ...
PROBMELA: a modeling language for communicating probabilistic processes
, 2004
"... Building automated tools to address the analysis of reactive probabilistic systems requires a simple, but expressive input language with a formal semantics based on a probabilistic operational model that can serve as starting point for verification algorithms. We introduce a higher level description ..."
Abstract

Cited by 10 (3 self)
 Add to MetaCart
Building automated tools to address the analysis of reactive probabilistic systems requires a simple, but expressive input language with a formal semantics based on a probabilistic operational model that can serve as starting point for verification algorithms. We introduce a higher level description language for probabilistic parallel programs with shared variables, message passing via synchronous and (perfect or lossy) fifo channels and atomic regions and provide a structured operational semantics. Applied to finitestate systems, the semantics can serve as basis for the algorithmic generation of a Markov decision process that models the stepwise behavior of the given system.
Domain Equations for Probabilistic Processes (Extended Abstract)
 IN PROC. EXPRESS'97. ELECTRONIC NOTES IN THEORETICAL COMPUTER SCIENCE 7
, 1997
"... In this paper we consider Milner's calculus CCS enriched by a probabilistic choice operator. The calculus is given operational semantics based on probabilistic transition systems. We define operational notions of preorder and equivalence as probabilistic extensions of the simulation preorder a ..."
Abstract

Cited by 9 (3 self)
 Add to MetaCart
In this paper we consider Milner's calculus CCS enriched by a probabilistic choice operator. The calculus is given operational semantics based on probabilistic transition systems. We define operational notions of preorder and equivalence as probabilistic extensions of the simulation preorder and the bisimulation equivalence respectively. We extend existing categorytheoretic techniques for solving domain equations to the probabilistic case and give two denotational semantics for the calculus. The first, "smooth", semantic model arises as a solution of a domain equation involving the probabilistic powerdomain and solved in the category CONT? of continuous domains. The second model also involves appropriately restricted probabilistic powerdomain, but is constructed i...
A Fully Abstract MetricSpace Denotational Semantics for Reactive Probabilistic Processes
 In Proc. COMPROX '98, Electronic Notes in TCS vol.13
, 1998
"... MetricSpace Denotational Semantics for Reactive Probabilistic Processes M.Z. Kwiatkowska and G.J. Norman School of Computer Science, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK Abstract We consider the calculus of Communicating Sequential Processes (CSP) [8] extended with act ..."
Abstract

Cited by 7 (1 self)
 Add to MetaCart
MetricSpace Denotational Semantics for Reactive Probabilistic Processes M.Z. Kwiatkowska and G.J. Norman School of Computer Science, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK Abstract We consider the calculus of Communicating Sequential Processes (CSP) [8] extended with actionguarded probabilistic choice and provide it with an operational semantics in terms of a suitable extension of Larsen and Skou's [14] reactive probabilistic transition systems. We show that a testing equivalence which identi es two processes if they pass all tests with the same probability is a congruence for a subcalculus of CSP including external and internal choice and the synchronous parallel. Using the methodology of de Bakker and Zucker [3] introduced for classical process calculi, we derive a metricspace semantic model for the calculus and show it is fully abstract.
Metric semantics for reactive probabilistic processes
, 1997
"... In this thesis we present three mathematical frameworks for the modelling of reactive probabilistic communicating processes. We first introduce generalised labelled transition systems as a model of such processes and introduce an equivalence, coarser than probabilistic bisimulation, over these syst ..."
Abstract

Cited by 6 (1 self)
 Add to MetaCart
In this thesis we present three mathematical frameworks for the modelling of reactive probabilistic communicating processes. We first introduce generalised labelled transition systems as a model of such processes and introduce an equivalence, coarser than probabilistic bisimulation, over these systems. Two processes are identified with respect to this equivalence if, for all experiments, the probabilities of the respective processes passing a given experiment are equal. We next consider a probabilistic process calculus including external choice, internal choice, actionguarded probabilistic choice, synchronous parallel and recursion. We give operational semantics for this calculus be means of our generalised labelled transition systems and show that our equivalence is a congruence for this language. Following the methodology introduced by de Bakker & Zucker, we then give denotational semantics to the calculus by means of a complete metric space of probabilistic processes. The derived metric, although not an ultrametric, satisfies the intuitive property that the distance between two processes tends to 0 if a measure of the dif
Mixing Up Nondeterminism and Probability: a preliminary report
, 1999
"... For a process language with both nondeterministic and probabilistic choice, and a form of failure a transition system is given from which, in a modular way, various operational models corresponding to various interpretations of nondeterminism and probability can be obtained. The effect of failure of ..."
Abstract

Cited by 6 (4 self)
 Add to MetaCart
For a process language with both nondeterministic and probabilistic choice, and a form of failure a transition system is given from which, in a modular way, various operational models corresponding to various interpretations of nondeterminism and probability can be obtained. The effect of failure of one component for the system as a whole is treated differently in each interpretation. The same approach is followed for an extension of the language with a parallel operator. The adopted concurrency model is of a distributed nature and assumes that progress is guaranteed if nonfailing components exist. To this end the notion of a takeover of a failing component is incorporated in the transition system. It is shown that the modular way in which the transition system can yield different semantical models applies to this setting as well.
Metric Denotational Semantics for PEPA
 Proceedings of the Fourth Annual Workshop on Process Algebra and Performance Modelling
, 1996
"... Stochastic process algebras, which combine the features of a process calculus with stochastic analysis, were introduced to enable compositional performance analysis of systems. At the level of syntax, compositionality presents itself in terms of operators, which can be used to build more complex sys ..."
Abstract

Cited by 5 (1 self)
 Add to MetaCart
Stochastic process algebras, which combine the features of a process calculus with stochastic analysis, were introduced to enable compositional performance analysis of systems. At the level of syntax, compositionality presents itself in terms of operators, which can be used to build more complex systems from simple components. Denotational semantics is a method for assigning to syntactic objects elements of a suitably chosen semantic domain. This is compositional in style, as operators are represented by certain functions on the domain, and often allows to gain additional insight by considering the properties of those functions. We consider Performance Evaluation Process Algebra (PEPA), a stochastic process algebra introduced by Hillston [9]. Based on the methodology introduced by de Bakker & Zucker, we give denotational semantics to PEPA by means of a complete metric space of suitably enriched trees. We investigate continuity properties of the PEPA operators and show that our semantic...