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Closed, Open, and Robust Timed Networks
Parosh Aziz Abdulla, Johann Deneux, and Pritha Mahata 1
Dept. of Information Technology, Uppsala University, Sweden
Abstract
We consider verification of safety properties for parameterized systems of timed processes,
so called timed networks. A timed network consists of a finite state process, called a con­
troller, and an arbitrary set of identical timed processes. In [AJ03] it was shown that check­
ing safety properties is decidable in the case where each timed process is equipped with a
single real­valued clock. In [ADM04], we showed that this is no longer possible if each
timed process is equipped with at least two real­valued clocks. In this paper, we study two
subclasses of timed networks: closed and open timed networks. In closed timed networks,
all clock constraints are non­strict, while in open timed networks, all clock constraints are
strict (thus corresponds to syntactic removal of equality testing). We show that the prob­
lem becomes decidable for closed timed network, while it remains undecidable for open
timed networks. We also consider robust semantics of timed networks by introducing tim­
ing fuzziness through semantic removal of equality testing. We show that the problem is
undecidable both for closed and open timed networks under the robust semantics.

Source: Abdulla, Parosh Aziz - Department of Information Technology, Uppsala Universitet

Collections: Computer Technologies and Information Sciences