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108
Turning SOS Rules into Equations
, 1994
"... Many process algebras are defined by structural operational semantics (SOS). Indeed, most such definitions are nicely structured and fit the GSOS format of [15]. We give a procedure for converting any GSOS language definition to a finite complete equational axiom system (possibly with one infinit ..."
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Cited by 87 (20 self)
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Many process algebras are defined by structural operational semantics (SOS). Indeed, most such definitions are nicely structured and fit the GSOS format of [15]. We give a procedure for converting any GSOS language definition to a finite complete equational axiom system (possibly with one infinitary induction principle) which precisely characterizes strong bisimulation of processes.
The safety guaranteeing system at station HoornKersenboogerd

"... At the Dutch station HoornKersenboogerd, computer equipment is used for the safe and in time movement of trains. The computer equipment can be divided in two layers. A top layer offering an interface and means to help a human operator in scheduling train movement. And a bottom layer which checks wh ..."
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Cited by 43 (4 self)
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At the Dutch station HoornKersenboogerd, computer equipment is used for the safe and in time movement of trains. The computer equipment can be divided in two layers. A top layer offering an interface and means to help a human operator in scheduling train movement. And a bottom layer which checks whether commands issued by the top layer can safely be executed by the rail hardware and which acts appropriately on detection of a hazardous situation. The bottom layer is implemented with a programmable piece of equipment namely a Vital Processor Interlocking (VPI). This paper introduces the most important features of the VPI at HoornKersenboogerd. This particular VPI is modelled in CRL. Furthermore, the paper touches upon correctness criteria and tool support for VPIs, and suggests ways for verification of properties of VPIs. Experiments show that it is indeed possible to efficiently verify these correctness criteria.
Action Transducers and Timed Automata
 Formal Aspects of Computing
, 1996
"... The timed automaton model of [LV92, LV93] is a general model for timingbased systems. A notion of timed action transducer is here defined as an automatatheoretic way of representing operations on timed automata. It is shown that two timed trace inclusion relations are substitutive with respect to ..."
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Cited by 40 (13 self)
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The timed automaton model of [LV92, LV93] is a general model for timingbased systems. A notion of timed action transducer is here defined as an automatatheoretic way of representing operations on timed automata. It is shown that two timed trace inclusion relations are substitutive with respect to operations that can be described by timed action transducers. Examples are given of operations that can be described in this way, and a preliminary proposal is given for an appropriate language of operators for describing timingbased systems.
On the Relationship Between Process Algebra and Input/Output Automata (Extended Abstract)
 In Proceedings 6 th Annual Symposium on Logic in Computer Science
, 1991
"... ) Frits W. Vaandrager MIT Laboratory for Computer Science Cambridge, MA 02139, USA frits@theory.lcs.mit.edu Abstract The relation between process algebra and I/O automata models is investigated in a general setting of structured operational semantics (SOS). For a series of (approximations of) key p ..."
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Cited by 39 (1 self)
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) Frits W. Vaandrager MIT Laboratory for Computer Science Cambridge, MA 02139, USA frits@theory.lcs.mit.edu Abstract The relation between process algebra and I/O automata models is investigated in a general setting of structured operational semantics (SOS). For a series of (approximations of) key properties of I/O automata, syntactic constraints on inference rules are proposed which guarantee these properties. A first result is that, in a setting without assumptions about actions, the wellknown trace and failure preorders are substitutive for any set of rules in a format due to De Simone. Next additional constraints are imposed which capture the notion of internal actions and guarantee substitutivity of the testing preorders of De Nicola and Hennessy, and also of a preorder related to the failure semantics with fair abstraction of unstable divergence of Bergstra, Klop and Olderog. Subsequent constraints guarantee that input actions are always enabled and output actions cannot be bl...
Refinement of Actions and Equivalence Notions for Concurrent Systems
 Acta Informatica
, 1998
"... This paper combines and extends the material of [GGa/c/d/e], except for the part in [GGc] on refinement of transitions in Petri nets and the discussion of TCSPlike parallel composition in [GGe]. An informal presentation of some basic ingredients of this paper appeared as [GGb]. Among others, th ..."
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Cited by 38 (1 self)
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This paper combines and extends the material of [GGa/c/d/e], except for the part in [GGc] on refinement of transitions in Petri nets and the discussion of TCSPlike parallel composition in [GGe]. An informal presentation of some basic ingredients of this paper appeared as [GGb]. Among others, the treatment of action refinement in stable and nonstable event structures is new. The research reported here was supported by Esprit project 432 (METEOR), Esprit Basic Research Action 3148 (DEMON), Sonderforschungsbereich 342 of the TU Munchen, ONR grant N0001492J1974 and the Human Capital and Mobility Cooperation Network EXPRESS (Expressiveness of Languages for Concurrency). Contents
Using Dynamic Classes and Role Classes to Model Object Migration
, 1995
"... In this paper, we argue that objectoriented models must be able to represent three kinds of taxonomic structures: static classes, dynamic classes, and role classes, that behave differently with respect to object migration. If CAR is a static subclass of V EHICLE, then a vehicle that is not a car ..."
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Cited by 38 (2 self)
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In this paper, we argue that objectoriented models must be able to represent three kinds of taxonomic structures: static classes, dynamic classes, and role classes, that behave differently with respect to object migration. If CAR is a static subclass of V EHICLE, then a vehicle that is not a car can never migrate to the CAR subclass. On the other hand, if EMP loyee is a dynamic subclass of PERSON object class, then a PERSON that is not an employee may migrate to EMP . In both cases, an instance of the subclass is identical to an instance of the superclass. By contrast, if EMP is modeled as a role class of PERSON , then every employee differs from every person, but a PERSON instance can acquire one or more EMP instances as roles. The distinctions between the three kinds of classes are orthogonal, so that we can have, for example, dynamic subclasses of object or role classes, or role classes of dynamic or static classes. The paper is divided into two parts. In the first, infor...
Finite equational bases in process algebra: Results and open questions
 Processes, Terms and Cycles: Steps on the Road to Infinity, LNCS 3838
, 2005
"... Abstract. Van Glabbeek (1990) presented the linear time/branching time spectrum of behavioral equivalences for finitely branching, concrete, sequential processes. He studied these semantics in the setting of the basic process algebra BCCSP, and tried to give finite complete axiomatizations for them. ..."
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Cited by 28 (19 self)
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Abstract. Van Glabbeek (1990) presented the linear time/branching time spectrum of behavioral equivalences for finitely branching, concrete, sequential processes. He studied these semantics in the setting of the basic process algebra BCCSP, and tried to give finite complete axiomatizations for them. Obtaining such axiomatizations in concurrency theory often turns out to be difficult, even in the setting of simple languages like BCCSP. This has raised a host of open questions that have been the subject of intensive research in recent years. Most of these questions have been settled over BCCSP, either positively by giving a finite complete axiomatization, or negatively by proving that such an axiomatization does not exist. Still some open questions remain. This paper reports on these results, and on the stateoftheart in axiomatizations for richer process algebras with constructs like sequential and parallel composition. 1
A Formalization of Objects Using Equational Dynamic Logic
, 1991
"... Ordersorted equational logic is extended with dynamic logic to a specification language for dynamic objects. Special attention is paid to different concepts of encapsulation that play a role in objectorientation. It is argued that the resulting language, CMSL, meets those requirements of the ob ..."
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Cited by 24 (9 self)
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Ordersorted equational logic is extended with dynamic logic to a specification language for dynamic objects. Special attention is paid to different concepts of encapsulation that play a role in objectorientation. It is argued that the resulting language, CMSL, meets those requirements of the objectoriented database system manifesto [6] that are applicable to objectoriented conceptual models (as opposed to OO databases).
Modal Logic, Transition Systems and Processes
, 1994
"... Transition systems can be viewed either as process diagrams or as Kripke structures. The first perspective is that of process theory, the second that of modal logic. This paper shows how various formalisms of modal logic can be brought to bear on processes. Notions of bisimulation can not only be mo ..."
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Cited by 22 (3 self)
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Transition systems can be viewed either as process diagrams or as Kripke structures. The first perspective is that of process theory, the second that of modal logic. This paper shows how various formalisms of modal logic can be brought to bear on processes. Notions of bisimulation can not only be motivated by operations on transition systems, but they can also be suggested by investigations of modal formalisms. To show that the equational view of processes from process algebra is closely related to modal logic, we consider various ways of looking at the relation between the calculus of basic process algebra and propositional dynamic logic. More concretely, the paper contains preservation results for various bisimulation notions, a result on the expressive power of propositional dynamic logic, and a definition of bisimulation which is the proper notion of invariance for concurrent propositional dynamic logic. Keywords: modal logic, transition systems, bisimulation, process algebra 1 In...