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On Structured Workflow Modelling
"... Recent years have seen the introduction of many commercial workflow management systems. While there are similarities between the languages of various of these systems, there are also significant differences. One particular area of differences is caused by the fact that di erent systems impose differ ..."
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Cited by 83 (16 self)
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Recent years have seen the introduction of many commercial workflow management systems. While there are similarities between the languages of various of these systems, there are also significant differences. One particular area of differences is caused by the fact that di erent systems impose different syntactic restrictions. For example, some work ow management systems do not allow the use of arbitrary loops. In such cases, business analysts have to choose between either conforming to the language in their speci cations or transforming these speci cations afterwards. The latter option is preferable as this allows for a separation of concerns. In this paper we investigate to what extent such transformations are possible in the context of various syntactical restrictions (the most restrictive of which will be referred to as structured workflows). We also provide a deep insight into the consequences, particularly in terms of expressive power, of imposing such restrictions.
Automated Compositional Markov Chain Generation for a PlainOld Telephone System
 SCIENCE OF COMPUTER PROGRAMMING
, 1999
"... Obtaining performance models, like Markov chains and queueing networks, for systems of significant complexity and magnitude is a di#cult task that is usually tackled using human intelligence and experience. This holds in particular for performance models of a highly irregular nature. In this paper w ..."
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Cited by 45 (25 self)
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Obtaining performance models, like Markov chains and queueing networks, for systems of significant complexity and magnitude is a di#cult task that is usually tackled using human intelligence and experience. This holds in particular for performance models of a highly irregular nature. In this paper we argue by means of a nontrivial example  a plainold telephone system (POTS)  that a stochastic extension of process algebra can diminish these problems by permitting an automatic generation of Markov chains. We introduce a stochastic process algebra that separates the advance of time and action occurrences. For the sake of specification convenience we incorporate an elapse operator that allows the modular description of time constraints where delays are described by continuous phasetype distributions. Using this language we provide a formal specification of the POTS and show how a stochastic process of more than 10 7 states is automatically obtained from this system description. ...
A Correctness Criterion for Asynchronous Circuit Validation and Optimization
, 1992
"... In order to reason about the correctness of asynchronous circuit implementations and specifications, Dill has developed a variant of trace theory[ 1]. Tracetheory describes the behavior of an asynchronous circuit by representing its possible executions as strings called"traces". A useful ..."
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Cited by 15 (7 self)
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In order to reason about the correctness of asynchronous circuit implementations and specifications, Dill has developed a variant of trace theory[ 1]. Tracetheory describes the behavior of an asynchronous circuit by representing its possible executions as strings called"traces". A useful relation defined in this theory is called conformance, which holds when one tracespecification can be safely substituted for another. We propose a new relation in the context of Dill's trace theory, called strong conformance. We show that this relation is capable of detecting certain errors in asynchronouscircuits that cannot bedetectedthrough conformance. Strong conformance also helps to justify circuit optimization rules whereacomponent is replaced by another component having extra capabilities (e.g.,itcan accept more inputs). The structural operators of Dill's tracetheory  compose, rename and hide  are shown to be monotonic with respect to strong conformance. Experiments arepresented using a modified version of Dill's tracetheory verifier which implements the check for strong conformance.
Equivalence checking for infinite systems using parameterized boolean equation systems
 In Proc. CONCURâ€™07, LNCS 4703
, 2007
"... Abstract. In this paper, we provide a transformation from the branching bisimulation problem for infinite, concurrent, dataintensive systems in linear process format, into solving Parameterized Boolean Equation Systems. We prove correctness and illustrate the approach with two examples. We also pro ..."
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Cited by 15 (9 self)
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Abstract. In this paper, we provide a transformation from the branching bisimulation problem for infinite, concurrent, dataintensive systems in linear process format, into solving Parameterized Boolean Equation Systems. We prove correctness and illustrate the approach with two examples. We also provide small adaptations to obtain similar transformations for strong and weak bisimulations and simulation equivalences. 1
and ISDN SYSTEMS
"... This paper studies testing based on iabelled transition systems, presenting two test generation algorithms with their corresponding implementation relations. The first algorithm assumes that implementations communicate with their environment via symmetric, synchronous interactions. It is based on t ..."
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This paper studies testing based on iabelled transition systems, presenting two test generation algorithms with their corresponding implementation relations. The first algorithm assumes that implementations communicate with their environment via symmetric, synchronous interactions. It is based on the theory of testing equivalence and preorder, as is most of the testing theory for labelled transition systems, and it is found in the literature in some slightly different variations. The second algorithm is based on the assumption that implementations communicate with their environment via inputs and outputs. Such implementations are formalized by restricting the class of labelled transition systems to those systems that can always accept input actions. For these implementations a testing theory is developed, analogous to the theory of testing equivalence and preorder. It consists of implementation relations formalizing the notion of conformance of these implementations with respect o labelled transition system specifications, test cases and test suites, test execution, the notion of passing a test suite, and the test generation algorithm, which is proved to produce sound test suites for one of the implementation relations.