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The Linear TimeBranching Time Spectrum II  The semantics of sequential systems with silent moves
, 1993
"... ion Rule (KFAR) (Baeten, Bergstra & Klop [3]), expresses a global fairness assumption. It says that when possible a system will escape from any cycle of internal actions. Some form of KFAR is crucial for many protocal verifications with unreliable channels, and for that reason preorders and equi ..."
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Cited by 311 (17 self)
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ion Rule (KFAR) (Baeten, Bergstra & Klop [3]), expresses a global fairness assumption. It says that when possible a system will escape from any cycle of internal actions. Some form of KFAR is crucial for many protocal verifications with unreliable channels, and for that reason preorders and equivalences that satisfy KFAR are of special interest. Must preorders and divergence sensitive ones cannot satisfy KFAR. In Bergstra, Klop & Olderog [7] it is shown that the combination of KFAR with failure semantics is inconsistent, but they formulate a weaker version of KFAR that is satisfied in failure maysemantics. Still the combination of KFAR \Gamma and the liveness requirement appears to require global testing, and is only satisfied in the semantics between contrasimulation (C) and stability respecting branching bisimulation (BB s ). These requirements would reduce the number of suitable preorders to 18. It is in general a good strategy to do your verifications using the finest preorde...
Branching Time and Abstraction in Bisimulation Semantics
 Journal of the ACM
, 1996
"... Abstract. In comparative concurrency semantics, one usually distinguishes between linear time and branching time semantic equivalences. Milner’s notion of ohsen~ation equirlalence is often mentioned as the standard example of a branching time equivalence. In this paper we investigate whether observa ..."
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Cited by 273 (14 self)
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Abstract. In comparative concurrency semantics, one usually distinguishes between linear time and branching time semantic equivalences. Milner’s notion of ohsen~ation equirlalence is often mentioned as the standard example of a branching time equivalence. In this paper we investigate whether observation equivalence really does respect the branching structure of processes, and find that in the presence of the unobservable action 7 of CCS this is not the case. Therefore, the notion of branching hisimulation equivalence is introduced which strongly preserves the branching structure of processes, in the sense that it preserves computations together with the potentials in all intermediate states that are passed through, even if silent moves are involved. On closed KSterms branching bisimulation congruence can be completely axiomatized by the single axiom scheme: a.(7.(y + z) + y) = a.(y + z) (where a ranges over all actions) and the usual laws for strong congruence. WC also establish that for sequential processes observation equivalence is not preserved under refinement of actions, whereas branching bisimulation is. For a large class of processes, it turns out that branching bisimulation and observation equivalence are the same. As far as we know, all protocols that have been verified in the setting of observation equivalence happen to fit in this class, and hence are also valid in the stronger setting of branching hisimulation equivalence.
A Process Algebraic Approach to the Specification and Analysis of ResourceBound RealTime Systems
 PROCEEDINGS OF THE IEEE
, 1994
"... Recently, significant progress has been made in the development of timed process algebras for the specification and analysis of realtime systems. This paper describes a timed process algebra called ACSR, which supports synchronous timed actions and asynchronous instantaneous events. Timed actions a ..."
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Cited by 66 (44 self)
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Recently, significant progress has been made in the development of timed process algebras for the specification and analysis of realtime systems. This paper describes a timed process algebra called ACSR, which supports synchronous timed actions and asynchronous instantaneous events. Timed actions are used to represent the usage of resources and to model the passage of time. Events are used to capture synchronization between processes. To be able to specify real systems accurately, ACSR supports a notion of priority that can be used to arbitrate among timed actions competing for the use of resources and among events that are ready for synchronization. The paper also includes a brief overview of other timed process algebras and discusses similarities and differences between them and ACSR.
A Process Algebra of Communicating Shared Resources with Dense Time and Priorities
 THEORETICAL COMPUTER SCIENCE
, 1997
"... ..."
Supervisory Control of Nondeterministic Systems with Driven Events via Prioritized Synchronization and Trajectory Models
 SIAM Journal of Control and Optimization
, 1995
"... We study the supervisory control of nondeterministic discrete event dynamical systems (DEDS's) with driven events in the setting of prioritized synchronization and trajectory models introduced by Heymann. Prioritized synchronization captures the notions of controllable, uncontrollable, and dri ..."
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Cited by 30 (8 self)
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We study the supervisory control of nondeterministic discrete event dynamical systems (DEDS's) with driven events in the setting of prioritized synchronization and trajectory models introduced by Heymann. Prioritized synchronization captures the notions of controllable, uncontrollable, and driven events in a natural way, and we use it for constructing supervisory controllers. The trajectory model is used for characterizing the behavior of nondeterministic DEDS's since it is a sufficiently detailed model (in contrast to the less detailed language or failures models), and serves as a language congruence with respect to the operation of prioritized synchronization. We obtain results concerning controllability and observability in this general setting. Keywords: discrete event systems, supervisory control, nondeterministic automata, driven events, prioritized synchronization, trajectory models AMS (MOS) subject classifications: 68Q75, 93B25, 93C83 1 Introduction Supervisory control o...
A ResourceBased Prioritized Bisimulation for RealTime Systems
 Information and Computation
, 1992
"... The behavior of concurrent, realtime systems can be specified using a process algebra called CCSR. The underlying computation model of CCSR is resourcebased, in which multiple resources execute synchronously, while processes assigned to the same resource are interleaved according to their prioriti ..."
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Cited by 20 (5 self)
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The behavior of concurrent, realtime systems can be specified using a process algebra called CCSR. The underlying computation model of CCSR is resourcebased, in which multiple resources execute synchronously, while processes assigned to the same resource are interleaved according to their priorities. CCSR allows the algebraic specification of timeouts, interrupts, periodic behaviors and exceptions. This paper develops a natural treatment of preemption, which is based not only on priority, but also on resource utilization and interresource synchronization. The preemption ordering leads to a term equivalence based on strong bisimulation, which is also a congruence with respect to the operators. Consequently the equivalence yields a compositional proof system, which is illustrated in the verification of a resourcesharing, producerconsumer problem. April 1, 1992 3 1 Introduction The timing behavior of a realtime system depends not only on delays due to process synchronization, bu...
On the Axiomatizability of Ready Traces, Ready Simulation and Failure Traces
"... We provide an answer to an open question, posed by van Glabbeek [4], regarding the axiomatizability of ready trace semantics. We prove that ..."
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Cited by 17 (12 self)
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We provide an answer to an open question, posed by van Glabbeek [4], regarding the axiomatizability of ready trace semantics. We prove that
Centralized and Decentralized Supervisory Control of Nondeterministic Systems Under Partial Observation
 SIAM Journal on Control and Optimization
, 1997
"... In this paper we extend our earlier work on supervisory control of nondeterministic systems using prioritized synchronization as the mechanism of control and trajectory model as the modeling formalism by considering design of supervisors under partial observation. We introduce the notion of observat ..."
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Cited by 16 (6 self)
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In this paper we extend our earlier work on supervisory control of nondeterministic systems using prioritized synchronization as the mechanism of control and trajectory model as the modeling formalism by considering design of supervisors under partial observation. We introduce the notion of observationcompatible systems and show that prioritized synchronous composition of observationcompatible systems can be used as a mechanism of control of nondeterministic systems under partial observation in presence of driven events. Necessary and sufficient conditions, that depend on the trajectory model as opposed to the language model of the plant, are obtained for the existence of centralized as well as decentralized supervision. Our work on centralized control shows that the results of the traditional supervisory control can be "extended" to the above setting provided the supervisor is deterministic and the observation mask is projection type. On the other hand, our work on decentralized co...
On finite alphabets and infinite bases: From ready pairs to possible worlds
 In Proceedings 7th Conference on Foundations of Software Science and Computation Structures (FOSSACS’04), Barcelona, LNCS 2987
, 2004
"... Abstract. We prove that if a finite alphabet of actions contains at least two elements, then the equational theory for the process algebra BCCSP modulo any semantics no coarser than readiness equivalence and no finer than possible worlds equivalence does not have a finite basis. This semantic range ..."
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Cited by 9 (7 self)
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Abstract. We prove that if a finite alphabet of actions contains at least two elements, then the equational theory for the process algebra BCCSP modulo any semantics no coarser than readiness equivalence and no finer than possible worlds equivalence does not have a finite basis. This semantic range includes ready trace equivalence. 1