M. Broy. Refinement of time. In ARTS'97, LNCS 1CS? SpringerVerlag, 1lag  Home/Search   Document Not in Database   Summary   Related Articles   Check

....diagram to a mixed signal architecture. The effect of each discretization can be validated by a simulation. Formally, behavior refinement may be defined as the containment of the input output relation of one (concrete) component in the corresponding relation of another (more abstract) component. [3] describes refinement involving a change of the underlying time model. Much of the work in this paper is based on [12] which discusses time refinement, relaxation, and discretization in the context of HyCharts. A related approach for the hybrid formalism Charon is described in [2] This paper is ....

M. Broy. Refinement of time. In Th. Rus M. Bertran, editor, Transformation-Based Reactive System Development. ARTS'97, Lecture Notes in Computer Science 1231, pages 44--63, 1997.

....time. Research in this area has produced a number of different approaches, notable among which are those based on timed traces, i.e. where systems are modelled by time varying functions. Examples include the duration calculus [17] the Temporal Agent Model (TAM) 13, 14] the timed stream model [3, 4] and the timed refinement calculus [9, 8] Each of these techniques comprises a specification notation for specifying (and reasoning about) systems and a refinement notation for transforming specifications towards implementations. The aim of this paper is to illustrate the utility of a recent ....

M. Broy. Refinement of time. In AMAST Workshop on Real-Time and Probabilistic Systems (ARTS'97), volume 1231 of LNCS. Springer-Verlag, 1997.

....action system for Theorem 3, 1; 1) and (1; 2) may execute alternately without (2; 1) ever occurring, with the result that the final output message msg remains empty. 5 Discussion Related work with similar aims is due to Abadi et al. 1994) de Boer et al. 1996) Fidge et al. 1997) and Broy (1997). 15 The approach of Abadi et al. 1994) uses the Temporal Logical of Actions (TLA) to reason about the real time properties of systems. Unlike our approach, TLA has a global time variable now, which is advanced by a tick action. Fairness constraints are used to execute this tick action and the ....

....of time across all processes. The variables up x and ac x are similar to our t i and mutex i;j . A compositional Hoare style proof system for a large class of distributed real time systems is presented by de Boer et al. 1996) The proof system is shown to be sound and relatively complete. Broy (1997) characterises the behaviour of processes by the histories of output variables relative to input variables. These histories are known as streams, and may be discrete sequences or continuous. The behaviours of processes are combined using parallel composition with feedback, and refinement is ....

Broy M. (1997) Refinement of Time, in Bertran M. and Rus T. (Eds.) Proc.

....way. The behavior of these components can be described by using HySCharts or by any technique from system theory that can be given a semantics in terms of dense input output relations. This includes differential equations. Dense input output relations are a relational extension of hybrid Focus [14, 4]. This paper completes and details our earlier work on HyCharts published in [8] and [9] 1.1. An Example The following example illustrates the kinds of systems we target at. It will be used throughout the paper to demonstrate the use of HyCharts. Example: An electronic height control system, ....

.... n C Theta is time guarded and guaranteed to be total in the input channel histories A R if n is time guarded and its output on channel C up to time t ffi is completely determined by its input up to time t on input channel C and by the input on the other input channels up to time t ffi [4]. i.e. its output on C reacts with a delay ffi 0 to input channel C. We also say that n is strongly time guarded on feedback channel C. The Connectors: Identity. We interpret the identity connector I A : A A by the identity relation I A which simply copies the input to the output: I A A ....

M. Broy. Refinement of time. In ARTS'97, LNCS 1231. Springer-Verlag, 1997.

....The behavior of these components can be described by using HySCharts or by any technique from system theory that can be given a semantics in terms of dense input output relations. This includes differential equations. Dense input output relations are a relational extension of hybrid Focus [MS97, Bro97] 1.1 An Example The following example illustrates the kinds of systems we target at. It will be used throughout the paper to demonstrate the use of HyCharts. Example 1 (An electronic height control system, EHC) The purpose of this system, which was originally proposed by BMW, is to control the ....

.... n C Theta is time guarded and guaranteed to be total in the input channel histories A R if n is time guarded and its output on channel C up to time t ffi is completely determined by its input up to time t on input channel C and by the input on the other input channels up to time t ffi [Bro97] i.e. its output on C reacts with a delay ffi 0 to input channel C. We also say that n is strongly time guarded on feedback channel C. The Connectors Identity. We interpret the identity connector I A : A A by the identity relation I A which simply copies the input to the output: I A A ....

M. Broy. Refinement of time. In ARTS'97, LNCS 1231. SpringerVerlag, 1997.

....development which allows errors and physical limitations to be introduced. It also allows properties of the new specification to be derived from those proved for the original. 1 Introduction Several formal notations have been developed for the specification and refinement of real time systems [19, 15, 16, 3, 13, 12]. To simplify specifications and subsequent analysis, most published case studies using these notations ignore the signal and timing errors which are inherent in any implementation, specifying instead ideal, error free systems. Such a simplifying approach to modelling and analysing systems is ....

M. Broy. Refinement of time. In AMAST Workshop on Real-Time and Probabilistic Systems (ARTS'97), volume 1231 of LNCS. Springer-Verlag, 1997.

....in turn are an abstraction of timed streams. Therefore, we can define an operator r to transform dense streams to (discrete) timed ones and to transform (discrete) timed streams to untimed streams. Some variants of r are given in the following sections. Others are possible. For example, in [Bro97] a version of r is defined that transforms streams of kind M 122 , i.e. streams that are piecewise constant and right continuous, to an equivalent of message streams. 5.2.1. From Message Streams to Timed Streams When abstracting from a dense stream M R to a discrete timed stream of kind ....

....x(n Delta T ) Note that a new message occurs in the timed stream even if the value of the dense stream does not change between consecutive intervals. 5.2.3. From Timed to Untimed Streams The abstraction r(x) from timed to untimed streams results from concatenating all sequences in stream x [Bro97] It is inductively defined as follows: r 2 (M ) 1 M r(a x) a r(x) for a 2 M and x 2 (M ) 1 . 5.2.4. Abstraction of Behaviors Based on an abstraction operator r T : M (M ) 1 for streams, r T can be extended to sets of stream processing functions. The extended ....

M. Broy. Refinement of time. In ARTS'97, volume 1231 of LNCS. Springer-Verlag, 1997.

....a typical evolution. these components can be described by using HySCharts or by any technique from system theory that can be given a semantics in terms of dense input output relations. This includes differential equations. Dense input output relations are a relational extension of hybrid Focus [10, 4]. Example 1 (An electronic height control system, EHC) The following example illustrates the kind of systems we want to regard. It will be used throughout the paper to demonstrate the use of HyCharts. The purpose of the electronic height control system (EHC) which was originally proposed by ....

M. Broy. Refinement of time. In ARTS'97, LNCS 1231. Springer-Verlag, 1997.

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M. Broy. Refinement of time. In ARTS'97, LNCS 1CS? SpringerVerlag, 1lag

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M. Broy. Refinement of time. In Th. Rus M. Bertran, editor, Transformation-Based Reactive System Development. ARTS'97, Lecture Notes in Computer Science 1231, pages 44--63, 1997.

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M. Broy. Refinement of time. In ARTS'97. to appear, 1997.

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M. Broy. Refinement of time. In ARTS'97, volume 1231 of LNCS. Springer-Verlag, 1997.

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M. Broy. Refinement of time. In ARTS'97, volume 1231 of LNCS. Springer-Verlag, 1997.

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M. Broy. Refinement of time. In ARTS'97. to appear, 1997.

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