Results 1  10
of
61
A tutorial on EMPA: A theory of concurrent processes with nondeterminism, priorities, probabilities and time
 Theoretical Computer Science
, 1998
"... In this tutorial we give an overview of the process algebra EMPA, a calculus devised in order to model and analyze features of realworld concurrent systems such as nondeterminism, priorities, probabilities and time, with a particular emphasis on performance evaluation. The purpose of this tutorial ..."
Abstract

Cited by 117 (11 self)
 Add to MetaCart
(Show Context)
In this tutorial we give an overview of the process algebra EMPA, a calculus devised in order to model and analyze features of realworld concurrent systems such as nondeterminism, priorities, probabilities and time, with a particular emphasis on performance evaluation. The purpose of this tutorial is to explain the design choices behind the development of EMPA and how the four features above interact, and to show that a reasonable trade off between the expressive power of the calculus and the complexity of its underlying theory has been achieved.
Process Algebra for Performance Evaluation
, 2000
"... This paper surveys the theoretical developments in the field of stochastic process algebras, process algebras where action occurrences may be subject to a delay that is determined by a random variable. A huge class of resourcesharing systems  like largescale computers, clientserver architectur ..."
Abstract

Cited by 71 (13 self)
 Add to MetaCart
This paper surveys the theoretical developments in the field of stochastic process algebras, process algebras where action occurrences may be subject to a delay that is determined by a random variable. A huge class of resourcesharing systems  like largescale computers, clientserver architectures, networks  can accurately be described using such stochastic specification formalisms.
An Efficient Algorithm for Aggregating PEPA Models
 IEEE Transactions on Software Engineering
, 1999
"... Performance Evaluation Process Algebra (PEPA) is a formal language for performance modelling based on process algebra. It has previously been shown that using the process algebra apparatus compact performance models can be derived which retain the essential behavioural characteristics of the modelle ..."
Abstract

Cited by 63 (30 self)
 Add to MetaCart
Performance Evaluation Process Algebra (PEPA) is a formal language for performance modelling based on process algebra. It has previously been shown that using the process algebra apparatus compact performance models can be derived which retain the essential behavioural characteristics of the modelled system. However no efficient algorithm for this derivation was given. In this paper we present an efficient algorithm which recognises and takes advantage of symmetries within the model and avoids unnecessary computation. The algorithm is illustrated by a multiprocessor example. Keywords: Performance modelling, model aggregation, performance evaluation tools, stochastic process algebras. 1 Introduction In recent years several Markovian process algebras (MPAs) have been presented in the literature. These include PEPA [1], MTIPP [2], and EMPA [3]. As with classical process algebras, these formalisms allow models of systems to be constructed which are amenable to functional or behavioural an...
On process rate semantics
 Theoretical Computer Science
, 2008
"... We provide translations between process algebra and systems of chemical reactions. We show that the translations preserve discretestate (stochastic) and continuousstate (concentration) semantics, and in particular that the continuousstate semantics of processes corresponds to the differential equ ..."
Abstract

Cited by 53 (11 self)
 Add to MetaCart
(Show Context)
We provide translations between process algebra and systems of chemical reactions. We show that the translations preserve discretestate (stochastic) and continuousstate (concentration) semantics, and in particular that the continuousstate semantics of processes corresponds to the differential equations of chemistry based on the law of mass action. The novel semantics of processes so obtained equates processes that have the same state occupation dynamics, but that may have different interaction interfaces. 1
Compositional Performance Modelling with the TIPPtool
 PERFORMANCE EVALUATION
, 1998
"... Stochastic Process Algebras have been proposed as compositional specification formalisms for performance models. In this paper, we describe a tool which aims at realising all beneficial aspects of compositional performance modelling, the TIPPtool. It incorporates methods for compositional specificat ..."
Abstract

Cited by 53 (19 self)
 Add to MetaCart
Stochastic Process Algebras have been proposed as compositional specification formalisms for performance models. In this paper, we describe a tool which aims at realising all beneficial aspects of compositional performance modelling, the TIPPtool. It incorporates methods for compositional specification as well as solution, based on stateofthearttechniques, and wrapped in a userfriendly graphical front end. Apart from highlighting the general benefits of the tool, we also discuss some lessons learned during development and application of the TIPPtool. A nontrivial model of a real life communication system serves as a case study to illustrate benefits and limitations.
Extended Markovian Process Algebra
, 1996
"... . EMPA enhances the expressiveness of classical process algebras by integrating functional and performance descriptions of concurrent systems. This is achieved by offering, besides passive actions (useful for pure nondeterminism), actions whose duration is exponentially distributed as well as immedi ..."
Abstract

Cited by 52 (5 self)
 Add to MetaCart
. EMPA enhances the expressiveness of classical process algebras by integrating functional and performance descriptions of concurrent systems. This is achieved by offering, besides passive actions (useful for pure nondeterminism), actions whose duration is exponentially distributed as well as immediate actions (useful for performance abstraction), parametrized by priority levels (hence prioritized choices) and weights (hence probabilistic choices). In order to analyze an EMPA term, from its integrated semantic model (a transition system labeled on both action types and action durations) we derive a functional semantic model (a transition system labeled on action types only) and a performance semantic model (a Markov chain). We show that an integrated analysis, i.e. a notion of equivalence on the integrated semantic model, is not only convenient but also necessary to achieve compositionality. 1 Introduction The need of integrating the performance modeling and analysis of a concurrent s...
D.: Symmetry reduction for probabilistic model checking
 International Organization for Standardization. ISO Information Processing Systems  Data Communication HighLevel Data Link Control Procedure  Frame Structure. IS 3309
, 2006
"... Abstract. We present an approach for applying symmetry reduction techniques to probabilistic model checking, a formal verification method for the quantitative analysis of systems with stochastic characteristics. We target systems with a set of nontrivial, but interchangeable, components such as tho ..."
Abstract

Cited by 45 (13 self)
 Add to MetaCart
(Show Context)
Abstract. We present an approach for applying symmetry reduction techniques to probabilistic model checking, a formal verification method for the quantitative analysis of systems with stochastic characteristics. We target systems with a set of nontrivial, but interchangeable, components such as those which commonly arise in randomised distributed algorithms or probabilistic communication protocols. We show, for three types of probabilistic models, that symmetry reduction, similarly to the nonprobabilistic case, allows verification to instead be performed on a bisimilar quotient model which may be up to factorially smaller. We then propose an efficient algorithm for the construction of the quotient model using a symbolic implementation based on multiterminal binary decision diagrams (MTBDDs) and, using four large case studies, demonstrate that this approach offers not only a dramatic increase in the size of probabilistic model which can be quantitatively analysed but also a significant decrease in the corresponding runtimes. 1
A Stochastic CausalityBased Process Algebra
, 1995
"... This paper discusses stochastic extensions of a simple process algebra in a causalitybased setting. Atomic actions are supposed to happen after a delay that is determined by a stochastic variable with a certain distribution. A simple stochastic type of event structures is discussed, restricting the ..."
Abstract

Cited by 34 (12 self)
 Add to MetaCart
This paper discusses stochastic extensions of a simple process algebra in a causalitybased setting. Atomic actions are supposed to happen after a delay that is determined by a stochastic variable with a certain distribution. A simple stochastic type of event structures is discussed, restricting the distribution functions to be exponential. A corresponding operational semantics of this model is given and compared to existing (interleaved) approaches. Secondly, a stochastic variant of event structures is discussed where distributions are of a much more general nature, viz. of phasetype. This includes exponential, Erlang, Coxian and mixtures of exponential distributions. 1. INTRODUCTION
Probabilistic Automata: System Types, Parallel Composition and Comparison
 In Validation of Stochastic Systems: A Guide to Current Research
, 2004
"... We survey various notions of probabilistic automata and probabilistic bisimulation, accumulating in an expressiveness hierarchy of probabilistic system types. The aim of this paper is twofold: On the one hand it provides an overview of existing types of probabilistic systems and, on the other ha ..."
Abstract

Cited by 33 (5 self)
 Add to MetaCart
We survey various notions of probabilistic automata and probabilistic bisimulation, accumulating in an expressiveness hierarchy of probabilistic system types. The aim of this paper is twofold: On the one hand it provides an overview of existing types of probabilistic systems and, on the other hand, it explains the relationship between these models.
A Formal Approach to the Integration of Performance Aspects in the Modeling and Analysis of Concurrent Systems
 Information and Computation
, 1998
"... A formal approach for modeling and analyzing concurrent systems is proposed which integrates performance characteristics in the early stages of the design process. The approach relies on both stochastically timed process algebras and stochastically timed Petri nets in order to exploit their compleme ..."
Abstract

Cited by 29 (13 self)
 Add to MetaCart
A formal approach for modeling and analyzing concurrent systems is proposed which integrates performance characteristics in the early stages of the design process. The approach relies on both stochastically timed process algebras and stochastically timed Petri nets in order to exploit their complementary advantages. The approach is instantiated to the case of EMPA (Extended Markovian Process Algebra), introduced together with the collection of its four semantics and the notion of equivalence that are required in order to implement the approach. Finally, the case study of the alternating bit protocol is presented to illustrate the adequacy of the approach. 1