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33
Reactive, Generative and Stratified Models of Probabilistic Processes
 Information and Computation
, 1990
"... ion Let E; E 0 be PCCS expressions. The intermodel abstraction rule IMARGR is defined by E ff[p] \Gamma\Gamma! i E 0 =) E ff[p= G (E;fffg)] ae \Gamma\Gamma\Gamma\Gamma\Gamma\Gamma! i E 0 This rule uses the generative normalization function to convert generative probabilities to reactive ..."
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Cited by 155 (7 self)
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ion Let E; E 0 be PCCS expressions. The intermodel abstraction rule IMARGR is defined by E ff[p] \Gamma\Gamma! i E 0 =) E ff[p= G (E;fffg)] ae \Gamma\Gamma\Gamma\Gamma\Gamma\Gamma! i E 0 This rule uses the generative normalization function to convert generative probabilities to reactive ones, thereby abstracting away from the relative probabilities between different actions. We can now define 'GR ('G (P )) as the reactive transition system that can be inferred from P 's generative transition system via IMARGR . By the same procedure as described at the end of Section 3.1, 'GR can be extended to a mapping 'GR : j GG ! j GR . Write P GR ¸ Q if P; Q 2 Pr are reactive bisimulation equivalent with respect to the transitions derivable from G+IMARGR , i.e. the theory obtained by adding IMARGR to the rules of Figure 7. The equivalence GR ¸ is defined just like R ¸ but using the cPDF ¯GR instead of ¯R . ¯GR is defined by ¯GR (P; ff; S) = X i2I R (=I G ) fj p i j G+ I...
A Congruence Theorem for Structured Operational Semantics With Predicates
, 1993
"... . We proposed a syntactical format, the path format, for structured operational semantics in which predicates may occur. We proved that strong bisimulation is a congruence for all the operators that can be defined within the path format. To show that this format is useful we provided many examples t ..."
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Cited by 109 (5 self)
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. We proposed a syntactical format, the path format, for structured operational semantics in which predicates may occur. We proved that strong bisimulation is a congruence for all the operators that can be defined within the path format. To show that this format is useful we provided many examples that we took from the literature about CCS, CSP, and ACP; they do satisfy the path format but no formats proposed by others. The examples include concepts like termination, convergence, divergence, weak bisimulation, a zero object, side conditions, functions, real time, discrete time, sequencing, negative premises, negative conclusions, and priorities (or a combination of these notions). Key Words & Phrases: structured operational semantics, term deduction system, transition system specification, structured state system, labelled transition system, strong bisimulation, congruence theorem, predicate. 1980 Mathematics Subject Classification (1985 Revision): 68Q05, 68Q55. CR Categories: D.3.1...
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 ..."
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Cited by 95 (9 self)
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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.
Weak Bisimulation for Fully Probabilistic Processes
, 1999
"... Bisimulations that abstract from internal computation have proven to be useful for verification of compositionally defined transition systems. In the literature of probabilistic extensions of such transition systems, similar bisimulations are rare. In this paper, we introduce weak and branching bisi ..."
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Cited by 57 (7 self)
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Bisimulations that abstract from internal computation have proven to be useful for verification of compositionally defined transition systems. In the literature of probabilistic extensions of such transition systems, similar bisimulations are rare. In this paper, we introduce weak and branching bisimulation for fully probabilistic systems, transition systems where nondeterministic branching is replaced by probabilistic branching. In contrast to the nondeterministic case, both relations coincide. We give an algorithm to decide weak (and branching) bisimulation with a time complexity cubic in the number of states of the fully probabilistic system. This meets the worst case complexity for deciding branching bisimulation in the nondeterministic case. In addition, the relation is shown to be a congruence with respect to the operators of PLSCCS , a lazy synchronous probabilistic variant of CCS. We illustrate that due to these properties, weak bisimulation provides all the crucial ingredients...
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 ..."
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Cited by 27 (5 self)
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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.
Establishing Qualitative Properties for Probabilistic Lossy Channel Systems: an Algorithmic Approach
 In Proceedings of 5th International AMAST Workshop on RealTime and Probabilistic Systems (ARTS’99
, 1999
"... . Lossy channel systems (LCSs) are models for communicating systems where the subprocesses are linked via unbounded FIFO channels which might lose messages. Link protocols, such as the Alternating Bit Protocol and HDLC can be modelled with these systems. The decidability of several verification ..."
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Cited by 23 (5 self)
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. Lossy channel systems (LCSs) are models for communicating systems where the subprocesses are linked via unbounded FIFO channels which might lose messages. Link protocols, such as the Alternating Bit Protocol and HDLC can be modelled with these systems. The decidability of several verification problems of LCSs has been investigated by Abdulla & Jonsson [AJ93,AJ94], e.g. they have shown that the reachability problem for LCSs is decidable while LTL model checking is not. In this paper, we consider probabilistic LCSs (which are LCSs where the transitions are augmented with appropriate probabilities) as introduced by [IN97] and show that the question of whether or not a linear time property holds with probability 1 is decidable. More precisely, we show how LTL nX model checking for (certain types of) probabilistic LCSs can be reduced to a reachability problem in a (nonprobabilistic) LCS where the latter can be solved with the methods of [AJ93]. 1 1 Introduction Traditiona...
Acceptance Trees for Probabilistic Processes
 In CONCUR'95, LNCS 962
, 1995
"... . In this paper we study the extension of classical testing theory to a probabilistic process algebra. We consider a generative interpretation of probabilities for a language with two choice operators (one internal and the other external), which are annotated with a probability p 2 (0; 1). We defin ..."
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Cited by 19 (8 self)
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. In this paper we study the extension of classical testing theory to a probabilistic process algebra. We consider a generative interpretation of probabilities for a language with two choice operators (one internal and the other external), which are annotated with a probability p 2 (0; 1). We define a testing semantics for our language, and we write P passp T to denote that the process P passes the test T with a probability p. We also give a set of essential tests which has the same strength as the full family of tests. Next we give an alternative characterization of the testing semantics, based on the idea of acceptance sets, and we prove that the new equivalence is equal to the testing equivalence. Finally, we present a fully abstract denotational semantics based on acceptance trees. 1 Introduction During the last years there has been a great activity devoted to the study of time and probabilistic extensions of concurrent processes. These extensions are very adequate for the spe...
Probabilistic metric semantics for a simple language with recursion
 Proc. Mathematical Foundations of Computer Science (MFCS), volume 1113 of Lecture Notes in Computer Science
, 1996
"... Abstract. We consider a simple divergencefree language RP for reactive processes which includes prefixing, deterministic choice, actionguarded probabilistic choice, synchronous parallel and recursion. We show that the probabilistic bisimulation of Larsen & Skou is a congruence for this language. Fo ..."
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Cited by 18 (6 self)
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Abstract. We consider a simple divergencefree language RP for reactive processes which includes prefixing, deterministic choice, actionguarded probabilistic choice, synchronous parallel and recursion. We show that the probabilistic bisimulation of Larsen & Skou is a congruence for this language. Following the methodology introduced by de Bakker & Zucker we give denotational semantics to this language by means of a complete metric space of (deterministic) probabilistic trees defined in terms of the powerdomain of closed sets. This new metric, although not an ultrametric, nevertheless specialises to the metric of de Bakker & Zucker. Our semantic domain admits a full abstraction result with respect to probabilistic bisimulation. 1
Compositional reasoning for probabilistic finitestate behaviors
 In Processes, Terms and Cycles: Steps on the Road to Infinity, Essays Dedicated to Jan Willem Klop, on the Occasion of His 60th Birthday, LNCS 3838
, 2005
"... Abstract. We study a process algebra which combines both nondeterministic and probabilistic behavior in the style of Segala and Lynch’s simple probabilistic automata. We consider strong bisimulation and observational equivalence, and provide complete axiomatizations for a language that includes para ..."
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Cited by 17 (4 self)
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Abstract. We study a process algebra which combines both nondeterministic and probabilistic behavior in the style of Segala and Lynch’s simple probabilistic automata. We consider strong bisimulation and observational equivalence, and provide complete axiomatizations for a language that includes parallel composition and (guarded) recursion. The presence of the parallel composition introduces various technical difficulties and some restrictions are necessary in order to achieve complete axiomatizations. 1
GSOS for Probabilistic Transition Systems
, 2002
"... We introduce PGSOS, an operator specification format for (reactive) probabilistic transition systems which bears similarity to the known GSOS format for labelled (nondeterministic) transition systems. Like the standard one, the format is well behaved in the sense that on all models bisimilarity is a ..."
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Cited by 13 (1 self)
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We introduce PGSOS, an operator specification format for (reactive) probabilistic transition systems which bears similarity to the known GSOS format for labelled (nondeterministic) transition systems. Like the standard one, the format is well behaved in the sense that on all models bisimilarity is a congruence and the uptocontext proof principle is valid. Moreover, guarded recursive equations involving the specified operators have unique solutions up to bisimilarity. These results generalize wellbehavedness results given in the literature for specific operators that turn out to be definable by our format. PGSOS arose from the following procedure: Turi and Plotkin proposed to model specifications in the (standard) GSOS format as natural transformations of a type they call abstract GSOS. This formulation allows for simple proofs of several wellbehavedness properties, such as bisimilarity being a congruence on all models of such a specification. First, we give a full proof of Turi and Plotkin's claim about the correspondence of abstract GSOS and standard GSOS for labelled transition systems. Next, we instantiate their categorical framework to yield a specification format for probabilistic transition systems. The main contribution of the present paper is the derivation of the PGSOS format as a rulestyle representation of the natural transformations obtained this way. We benefit from the fact that some parts of our argument for the nondeterministic case can be reused. The wellbehavedness results for abstract GSOS immediately carry over to the new concrete format.