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From Physical Modelling to Compositional Models of Hybrid Systems
 In Langmaack et al
, 1994
"... . By a hybrid system we mean a discrete controller in interaction with a physical environment. This paper discusses methodologies for incorporating physically grounded models in representations of hybrid systems. To this end, we study a driver support system, an example which includes unmodelled inp ..."
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Cited by 10 (9 self)
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. By a hybrid system we mean a discrete controller in interaction with a physical environment. This paper discusses methodologies for incorporating physically grounded models in representations of hybrid systems. To this end, we study a driver support system, an example which includes unmodelled inputs. We consider models at different levels of abstraction. First, we show that discrete models of the environment can be obtained from the continuous models without losing relevant information. We do this using an analysis of the continuous state space. We use Dynamic Transition Systems (DTS) for the modular modelling at this level of abstraction. Next, we consider models using Hybrid Transition Systems (HTS). This can be seen as a modular version of timed transition systems allowing both differential and algebraic equations in each mode. Finally, we comment on expressivity requirements on hybrid formalisms for modelling realistic physical systems. 1 Introduction A typical example of a hyb...
Verification of Embedded Systems using Synchronous Observers
 Proceedings of the 4th International Conference on Formal Techniques in Realtime and Faulttolerant Systems, LNCS 1135
, 1996
"... This paper is a study of observerbased proof techniques applied to the verification of a model of a real world embedded system, an aircraft landing gear. We present a formal description of these techniques (taken from [5]) and look at three ways of applying them, comparing verification of the com ..."
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Cited by 7 (4 self)
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This paper is a study of observerbased proof techniques applied to the verification of a model of a real world embedded system, an aircraft landing gear. We present a formal description of these techniques (taken from [5]) and look at three ways of applying them, comparing verification of the composed system with two approaches to decompositional verification. The example illustrates that due to the tight interaction in a plantcontroller setting there is often little to be gained by adopting a decompositional approach to verification. Nonetheless, two reasons are presented for separation between the controller and its environment at the modelling stage. Hence the result of the study is that in cases similar to this one, it is most expedient to prove system properties using the composed model derived from individual parts.
A study of Decompositional Verification of Hybrid Systems
, 1995
"... This paper is a study of decompositional proof techniques applied to the verification of a model of a real world hybrid system, an aircraft landing gear. We present a formal description of these techniques (taken from Halwbachs et.al. [5]) and look at two ways of applying them. We discover, and corr ..."
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Cited by 1 (0 self)
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This paper is a study of decompositional proof techniques applied to the verification of a model of a real world hybrid system, an aircraft landing gear. We present a formal description of these techniques (taken from Halwbachs et.al. [5]) and look at two ways of applying them. We discover, and correct, a flaw in the theory, but conclude ultimately that when dealing with a plantcontroller combination there is often little to be gained by adopting a decompositional approach to verification. Moreover we argue that in these cases the composed system can be even simpler than its components, and thus it is most expedient to prove properties of the system directly. Keywords: hybrid system, I/O machine, decompositional verification, Esterel. A study of Decompositional Verification of Hybrid Systems Martin Westhead (martinwe@aifh.ed.ac.uk) Dept. of Artificial Intelligence University of Edinburgh 5 Forrest Hill, Edinburgh, U.K. Simin NadjmTehrani (simin@ida.liu.se) Dept. of Compute...
Compositionality for Improving Model Checking
, 2000
"... Model checking is an automatic technique for verifying nite state systems: in this approach, properties are expressed in a temporal logic and systems are modelled as transition systems. A main problem of model checking is state explosion: very complex systems are often represented by transition syst ..."
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Model checking is an automatic technique for verifying nite state systems: in this approach, properties are expressed in a temporal logic and systems are modelled as transition systems. A main problem of model checking is state explosion: very complex systems are often represented by transition systems with a prohibitive number of states. The primary cause of this problem is the parallel composition of interacting processes. Many techniques have been proposed to attack this problem, among them compositional techniques. These techniques reduce state explosion exploiting the natural decomposition of complex systems into processes. In this paper we present a formulabased compositional rule that allows us to deduce a property of a parallel composition of processes by checking it only on a component process. Keywords: model checking, compositionality, temporal logic, state explosion. 1.