8,659 research outputs found
A Unifying Approach to Decide Relations for Timed Automata and their Game Characterization
In this paper we present a unifying approach for deciding various
bisimulations, simulation equivalences and preorders between two timed automata
states. We propose a zone based method for deciding these relations in which we
eliminate an explicit product construction of the region graphs or the zone
graphs as in the classical methods. Our method is also generic and can be used
to decide several timed relations. We also present a game characterization for
these timed relations and show that the game hierarchy reflects the hierarchy
of the timed relations. One can obtain an infinite game hierarchy and thus the
game characterization further indicates the possibility of defining new timed
relations which have not been studied yet. The game characterization also helps
us to come up with a formula which encodes the separation between two states
that are not timed bisimilar. Such distinguishing formulae can also be
generated for many relations other than timed bisimilarity.Comment: In Proceedings EXPRESS/SOS 2013, arXiv:1307.690
On Zone-Based Analysis of Duration Probabilistic Automata
We propose an extension of the zone-based algorithmics for analyzing timed
automata to handle systems where timing uncertainty is considered as
probabilistic rather than set-theoretic. We study duration probabilistic
automata (DPA), expressing multiple parallel processes admitting memoryfull
continuously-distributed durations. For this model we develop an extension of
the zone-based forward reachability algorithm whose successor operator is a
density transformer, thus providing a solution to verification and performance
evaluation problems concerning acyclic DPA (or the bounded-horizon behavior of
cyclic DPA).Comment: In Proceedings INFINITY 2010, arXiv:1010.611
MTL-Model Checking of One-Clock Parametric Timed Automata is Undecidable
Parametric timed automata extend timed automata (Alur and Dill, 1991) in that
they allow the specification of parametric bounds on the clock values. Since
their introduction in 1993 by Alur, Henzinger, and Vardi, it is known that the
emptiness problem for parametric timed automata with one clock is decidable,
whereas it is undecidable if the automaton uses three or more parametric
clocks. The problem is open for parametric timed automata with two parametric
clocks. Metric temporal logic, MTL for short, is a widely used specification
language for real-time systems. MTL-model checking of timed automata is
decidable, no matter how many clocks are used in the timed automaton. In this
paper, we prove that MTL-model checking for parametric timed automata is
undecidable, even if the automaton uses only one clock and one parameter and is
deterministic.Comment: In Proceedings SynCoP 2014, arXiv:1403.784
Non-blocking supervisory control for initialised rectangular automata
We consider the problem of supervisory control for a class of rectangular automata and more specifically for compact rectangular automata with uniform rectangular activity, i.e. initialised. The supervisory controller is state feedback and disables discrete-event transitions in order to solve the non-blocking forbidden state problem. The non-blocking problem is defined under both strong and weak conditions. For the latter maximally permissive solutions that are computable on a finite quotient space characterised by language equivalence are derived
Timed Automata Semantics for Analyzing Creol
We give a real-time semantics for the concurrent, object-oriented modeling
language Creol, by mapping Creol processes to a network of timed automata. We
can use our semantics to verify real time properties of Creol objects, in
particular to see whether processes can be scheduled correctly and meet their
end-to-end deadlines. Real-time Creol can be useful for analyzing, for
instance, abstract models of multi-core embedded systems. We show how analysis
can be done in Uppaal.Comment: In Proceedings FOCLASA 2010, arXiv:1007.499
Improving search order for reachability testing in timed automata
Standard algorithms for reachability analysis of timed automata are sensitive
to the order in which the transitions of the automata are taken. To tackle this
problem, we propose a ranking system and a waiting strategy. This paper
discusses the reason why the search order matters and shows how a ranking
system and a waiting strategy can be integrated into the standard reachability
algorithm to alleviate and prevent the problem respectively. Experiments show
that the combination of the two approaches gives optimal search order on
standard benchmarks except for one example. This suggests that it should be
used instead of the standard BFS algorithm for reachability analysis of timed
automata
Re-verification of a Lip Synchronization Protocol using Robust Reachability
The timed automata formalism is an important model for specifying and
analysing real-time systems. Robustness is the correctness of the model in the
presence of small drifts on clocks or imprecision in testing guards. A symbolic
algorithm for the analysis of the robustness of timed automata has been
implemented. In this paper, we re-analyse an industrial case lip
synchronization protocol using the new robust reachability algorithm. This lip
synchronization protocol is an interesting case because timing aspects are
crucial for the correctness of the protocol. Several versions of the model are
considered: with an ideal video stream, with anchored jitter, and with
non-anchored jitter
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