[SystemSafety] Modelling and coding guidelines: "Unambiguous Graphical Representation"

[Peter Bernard Ladkin]

Besides the comments here, I did get one private inquiry about Statecharts. So here's what more I
found out.

On 2016-02-27 08:15 , Peter Bernard Ladkin wrote:
> Concerning the ambiguity of certain constructs in Statecharts, 

... I contacted Gerald Lüttgen, one of the authors of the FSE 2000 paper. He says he hasn't worked
on Statecharts for a while, but notes that practical variants of the notation are incorporated into
the SCADE suite (Ansys/Esterel), UML state machines, and Simulink/Stateflow. There seems to be a
variety of "dialects".

He points out that the SCADE version is likely "mathematically cleanest". I understand that there is
a general requirement of determinism in SCADE specs. Neither the UML variant or the
Simulink/Stateflow variant are deterministic.

I asked about a compositional semantics of the Statecharts notation itself, since this is what
yields deterministic behaviour, at least on the level of the semantics of the notation. Gerald said
"this is tricky when chain reactions within one step are permitted by the Statecharts dialect, i.e.,
when the generation of one event triggers another transition within the same step. The reason is
that it involves the explicit capturing of causality between events.." and refers to a relatively
recent paper:

De Roever, W.-P., Lüttgen, G. and Mendler, M. What is in a step: New Perspectives on a classical
question. In Z. Manna and D. Peled, eds., Pnueli Festschrift, vol. 6200 of Lecture Notes in Computer
Science, pp. 370-399, July 2010, Springer-Verlag.

PBL

Prof. Peter Bernard Ladkin, Faculty of Technology, University of Bielefeld, 33594 Bielefeld, Germany
Je suis Charlie
Tel+msg +49 (0)521 880 7319  www.rvs.uni-bielefeld.de





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