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Foundations of Timed Concurrent Constraint Programming
 Proceedings of the Ninth Annual IEEE Symposium on Logic in Computer Science
, 1994
"... We develop a model for timed, reactive computation by extending the asynchronous, untimed concurrent constraint programming model in a simple and uniform way. In the spirit of process algebras, we develop some combinators expressible in this model, and reconcile their operational, logical and denota ..."
Abstract

Cited by 89 (10 self)
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We develop a model for timed, reactive computation by extending the asynchronous, untimed concurrent constraint programming model in a simple and uniform way. In the spirit of process algebras, we develop some combinators expressible in this model, and reconcile their operational, logical and denotational character. We show how programs may be compiled into finitestate machines with loopfree computations at each state, thus guaranteeing bounded response time. 1 Introduction and Motivation Reactive systems [12,3,9] are those that react continuously with their environment at a rate controlled by the environment. Execution in a reactive system proceeds in bursts of activity. In each phase, the environment stimulates the system with an input, obtains a response in bounded time, and may then be inactive (with respect to the system) for an arbitrary period of time before initiating the next burst. Examples of reactive systems are controllers and signalprocessing systems. The primary issu...
Angelic NonDeterminism in Concurrent Constraint Programming
, 1991
"... Concurrent constraint programming [Sar89,SR90,SRP91] is a simple and powerful model of computation based on the notions of storeasconstraint and process as information transducer. In this paper we describe a (domaintheoretic) semantic foundation for cc languages with ask, tell, parallel compositi ..."
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Cited by 30 (4 self)
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Concurrent constraint programming [Sar89,SR90,SRP91] is a simple and powerful model of computation based on the notions of storeasconstraint and process as information transducer. In this paper we describe a (domaintheoretic) semantic foundation for cc languages with ask, tell, parallel composition, hiding, recursion and angelic nondeterminism ("parallel backtracking"). This class of languages includes the cc/Herbrand language [Sar89] and a simpler reworking [HS91] of CHIP. Generalizing previous work on determinate constraint programming [JPP89,SRP91], we describe the semantics for such a language based on modelling a process as a set of constraints, with parallel composition (conjunction) given by set intersection and orparallel search (disjunction) given by set union. This is achieved by viewing processes as continuous linear closure operators on the Smyth powerdomain of the underlying constraint system. The model is shown to be fully abstract for the observation of finite appro...
Default Timed Concurrent Constraint Programming (Extended Abstract)
, 1995
"... We extend the model of [SJG94b] to express strong timeouts (and preemption): if an event A does not happen through time t, cause event B to happen at time t. Such constructs arise naturally in practice (e.g. in modeling transistors) and are supported in languages such as Esterel (through instanta ..."
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Cited by 8 (1 self)
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We extend the model of [SJG94b] to express strong timeouts (and preemption): if an event A does not happen through time t, cause event B to happen at time t. Such constructs arise naturally in practice (e.g. in modeling transistors) and are supported in languages such as Esterel (through instantaneous watchdogs) and Lustre (through the "current" operator). The fundamental conceptual difficulty posed by these operators is that they are nonmonotonic. We provide a simple compositional semantics to the nonmonotonic version of concurrent constraint programming (CCP) obtained by changing the underlying logic from intuitionistic logic to Reiter 's default logic [Rei80]. This allows us to use the same construction (uniform extension through time) to develop Default Timed CCP (Default tcc) as we had used to develop Timed CCP (tcc) from CCP [SJG94b]. Indeed the smooth embedding of CCP processes into Default cc processes lifts to a smooth embedding of tcc processes into Default t...