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38
An algebraic framework for urgency
 Information and Computation
, 2000
"... Timed formalisms are extensions of untimed ones by adding clocks, realvalued ..."
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Cited by 37 (5 self)
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Timed formalisms are extensions of untimed ones by adding clocks, realvalued
A Graphical Language with Formal Semantics for the Specification and Analysis of RealTime Systems
 In Proceedings of IEEE RealTime Systems Symposium. IEEE Computer
, 1995
"... Graphical Communicating Shared Resources, GCSR, is a formal language for the specification and analysis of realtime systems including their functional and resource requirements. GCSR allows a modular and hierarchical, and thus, scalable specification of a realtime system. GCSR supports notions of ..."
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Cited by 15 (7 self)
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Graphical Communicating Shared Resources, GCSR, is a formal language for the specification and analysis of realtime systems including their functional and resource requirements. GCSR allows a modular and hierarchical, and thus, scalable specification of a realtime system. GCSR supports notions of communication through events, interrupt, concurrency, and time to describe a realtime system. In addition, GCSR allows the explicit representation of resources and priorities to arbitrate resource contention in a natural way that produces easy to understand and modify specifications. The semantics of GCSR is the Algebra of Communicating Shared Resources, a timed process algebra with operational semantics. The process algebra provides behavioral equivalence relations which can be used to verify the correctness of one GCSR specification with respect to the other. 1 Introduction The potential high cost associated with the malfunctioning of realtime systems created a need for a formal framew...
A calculus and logic of resources and processes
 FAC, 18:495 – 517
, 2006
"... Recent advances in logics for reasoning about resources provide a new approach to compositional reasoning in interacting systems. We present a calculus of resources and processes, based on a development of Milner's synchronous calculus of communication systems, SCCS, that uses an explicit model of ..."
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Cited by 15 (7 self)
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Recent advances in logics for reasoning about resources provide a new approach to compositional reasoning in interacting systems. We present a calculus of resources and processes, based on a development of Milner's synchronous calculus of communication systems, SCCS, that uses an explicit model of resource. Our calculus models the coevolution of resources and processes with synchronization constrained by the availability of resources. We provide a logical characterization, analogous to HennessyMilner logic's characterization of bisimulation in CCS, of bisimulation between resource processes which is compositional in the concurrent and local structure of systems.
Symbolic Schedulability Analysis of Realtime Systems
, 1998
"... We propose a unifying method for analysis of scheduling problems in realtime systems. The method is based on ACSRVP, a realtime process algebra with valuepassing capabilities. We use ACSRVP to describe an instance of a scheduling problem as a process that has parameters of the problem as free v ..."
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Cited by 14 (5 self)
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We propose a unifying method for analysis of scheduling problems in realtime systems. The method is based on ACSRVP, a realtime process algebra with valuepassing capabilities. We use ACSRVP to describe an instance of a scheduling problem as a process that has parameters of the problem as free variables. The specification is analyzed by means of a symbolic algorithm. The outcome of the analysis is a set of equations, a solution to which yields the values of the parameters that make the system schedulable. Equations are solved using integer programming or constraint logic programming. The paper presents specifications of two scheduling problems as examples. This research was supported in part by NSF CCR9415346, NSF CCR9619910, AFOSR F496209510508, ARO DAAH049510092, and ONR N000149710505. 1 Introduction The desire to automate or incorporate intelligent controllers into control systems has lead to rapid growth in the demand for realtime software systems. Moreover, the...
A Process Algebra with Distributed Priorities
 Theoretical Computer Science
, 1996
"... . This paper presents a process algebra for distributed systems in which some actions may take precedence over others. In contrast with existing approaches to priorities, our algebra only allows actions to preempt others at the same #location" and therefore captures a notion of localizedprecedence. ..."
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Cited by 14 (3 self)
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. This paper presents a process algebra for distributed systems in which some actions may take precedence over others. In contrast with existing approaches to priorities, our algebra only allows actions to preempt others at the same #location" and therefore captures a notion of localizedprecedence. Using Park's and Milner's notion of strong bisimulation as a basis, we develop a behavioral congruence and axiomatize it for #nite processes; we also derive an associated observational congruence. Simple examples highlight the utility of the theory. 1 Introduction Process algebras #11, 13# provide widely studied frameworks for modeling and verifying concurrent systems #9#. Such theories typically consist of a simple language with a wellde#ned operational semantics given in terms of labeled transition systems; a behavioral equivalence is then used to relate implementations and speci#cations, which are both given as terms in the language. In order to facilitate compositional reasoning, in wh...
Information Extraction for Runtime Formal Analysis
, 2001
"... The significance of software systems has rapidly increased. The assurance of software systems has become a critical requirement of the information age. Formal verification on the design of a system and testing on a system implementation with a variety of inputs has been used for this purpose. Howeve ..."
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Cited by 10 (6 self)
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The significance of software systems has rapidly increased. The assurance of software systems has become a critical requirement of the information age. Formal verification on the design of a system and testing on a system implementation with a variety of inputs has been used for this purpose. However, verifying a design can not guarantee the correctness of an implementation. Although testing is performed on implementation, it does not give formal guarantees because it is not possible to test exhaustively. Runtime formal analysis is proposed to combat the weaknesses of formal verification and testing. Runtime formal analysis aims to assure the correctness of the current execution at runtime. Runtime formal analysis is performed based on a formal specification of system requirements. This dissertation proposes a framework for runtime formal analysis. We investigate general issues for the framework. We show that a set of the properties runtime formal analysis can detect is a subset...
A Process Algebraic Approach to the Schedulability Analysis of RealTime Systems
"... To engineer reliable realtime systems, it is desirable to detect timing anomalies early in the development process. However, there is little work addressing the problem of accurately predicting timing properties of realtime systems before implementations are developed. This paper describes an appr ..."
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Cited by 10 (4 self)
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To engineer reliable realtime systems, it is desirable to detect timing anomalies early in the development process. However, there is little work addressing the problem of accurately predicting timing properties of realtime systems before implementations are developed. This paper describes an approach to the specification and schedulability analysis of realtime systems based on the timed process algebra ACSRVP, which is an extension of ACSR with valuepassing communication and dynamic priorities. Combined with the existing features of ACSR for representing time, synchronization and resource requirements, ACSRVP is capable of specifying a variety of realtime systems with different scheduling disciplines in a modular fashion. Moreover, we can use VERSA, a toolkit we have developed for ACSR, to perform schedulability analysis on realtime systems specified in ACSRVP automatically by checking for a certain bisimulation relation. 1 Introduction The Communicating Shared Resources (CS...
Systems Modelling via Resources and Processes: Philosophy, Calculus, Semantics, and Logic
 GDP FESTSCHRIFT ENTCS, TO APPEAR
"... We describe a programme of research in resource semantics, concurrency theory, bunched logic, and stochastic processes, as applied to mathematical systems modelling. Motivated by a desire for structurally and semantically rigorous discrete event modelling tools, applicable to enterprisescale as wel ..."
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Cited by 9 (6 self)
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We describe a programme of research in resource semantics, concurrency theory, bunched logic, and stochastic processes, as applied to mathematical systems modelling. Motivated by a desire for structurally and semantically rigorous discrete event modelling tools, applicable to enterprisescale as well as componentscale systems, we introduce a new approach to compositional reasoning based on a development of SCCS with an explicit model of resource. Our calculus models the coevolution of resources and processes with synchronization constrained by the availability of resources. We provide a simple denotational semantics as a parametrization of Abramsky’s synchronization trees semantics for SCCS. We also provide a logical characterization, analogous to HennessyMilner logic’s characterization of bisimulation in CCS, of bisimulation between resource processes which is compositional in the concurrent and local structure of systems. We discuss applications to ideas such as location and access control.
A Monitoring and Checking Framework for Runtime Correctness Assurance
, 1998
"... Computer systems are often monitored for performance evaluation and enhancement, debugging and testing, control or to check for the correctness of the system. Recently, the problem of designing monitors to check for the correctness of system implementation has received increased attention from the r ..."
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Cited by 8 (2 self)
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Computer systems are often monitored for performance evaluation and enhancement, debugging and testing, control or to check for the correctness of the system. Recently, the problem of designing monitors to check for the correctness of system implementation has received increased attention from the research community. Traditionally, verification has been used to increase the confidence that a system will be correct by making sure that a design specification is correct. However, even if a design has been formally verified, it still does not ensure the correctness of an implementation of the design. This is because the implementation often is much more detailed, and may not strictly follow the formal design. So, there is possibility for introduction of errors into an implementation of a design that has been verified. One way that people have traditionally tried to overcome this gap between the design and the implementation has been to test the implementation's behavior on a predetermined set of input sequences. This approach, however, fails to provide guarantees about the correctness of the implementation on all possible input sequences. Consequently, when a system is running, it is hard to guarantee whether the current execution of the system is correct or not using the two
PARAGON: A Paradigm for the Specification, Verification, and Testing of RealTime Systems
 IN IEEE AEROSPACE CONFERENCE
"... The PARAGON toolset provides an environment for the modular and hierarchical design of resourcebound, realtime systems. It offers wellintegrated graphical and textual specification languages with formal semantics. Both languages are based on the Algebra of Communicating Shared Resources (ACSR), ..."
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Cited by 7 (5 self)
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The PARAGON toolset provides an environment for the modular and hierarchical design of resourcebound, realtime systems. It offers wellintegrated graphical and textual specification languages with formal semantics. Both languages are based on the Algebra of Communicating Shared Resources (ACSR), a process algebra with explicit notions of time, resources and priority. The integration of the three notions widens the applicability of the PARAGON formalisms to embedded systems, control systems, and faulttolerant systems where runtime resource requirements must be considered during the design phase. To facilitate the design of complex systems, PARAGON allows a designer to describe a system incrementally through refinement steps that preserve system properties. To increase dependentability of system models, PARAGON offers three types of analysis: automated verification of system requirements, interactive simulation, and testing. In this paper, we demonstrate the design methodology that PARAGON offers through examples.