Reactive Systems: Modelling, Specification and Verification - Cs.ioc.ee
Reactive Systems: Modelling, Specification and Verification - Cs.ioc.ee
Reactive Systems: Modelling, Specification and Verification - Cs.ioc.ee
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2.2. CCS, FORMALLY 31<br />
Exercise 2.8 Assume that A def<br />
= b.a.B. By using the SOS rules for CCS prove the<br />
existence of the following transitions:<br />
• (A | b.0) \ {b} τ → (a.B | 0) \ {b},<br />
• (A | b.a.B) + (b.A)[a/b] b → (A | a.B), <strong>and</strong><br />
• (A | b.a.B) + (b.A)[a/b] a → A[a/b].<br />
Exercise 2.9 Draw (part of) the transition graph for the process name A whose<br />
behaviour is given by the defining equation<br />
A def<br />
= (a.A) \ b .<br />
The resulting transition graph should have infinitely many states. Can you think of<br />
a CCS term that generates a finite labelled transition system that should intuitively<br />
have the same behaviour as A? <br />
Exercise 2.10 Draw (part of) the transition graph for the process name A whose<br />
behaviour is given by the defining equation<br />
A def<br />
= (a0.A)[f]<br />
where we assume that the set of channel names is {a0, a1, a2, . . .}, <strong>and</strong> f(ai) =<br />
ai+1 for each i.<br />
The resulting transition graph should (again!) have infinitely many states. Can<br />
you give an argument showing that there is no finite state labelled transition system<br />
that could intuitively have the same behaviour as A? <br />
Exercise 2.11<br />
1. Draw the transition graph for the process name Mutex1 whose behaviour is<br />
given by the defining equation<br />
Mutex1<br />
User<br />
def<br />
= (User | Sem) \ {p, v}<br />
def<br />
= ¯p.enter.exit.¯v.User<br />
Sem def<br />
= p.v.Sem .