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Robust reachability in timed automata: A gamebased approach
 Lab. Specification & Verification, ENS
, 2012
"... Abstract. Reachability checking is one of the most basic problems in verification. By solving this problem, one synthesizes a strategy that dictates the actions to be performed for ensuring that the target location is reached. In this work, we are interested in synthesizing “robust ” strategies for ..."
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Cited by 9 (4 self)
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Abstract. Reachability checking is one of the most basic problems in verification. By solving this problem, one synthesizes a strategy that dictates the actions to be performed for ensuring that the target location is reached. In this work, we are interested in synthesizing “robust ” strategies for ensuring reachability of a location in a timed automaton; with “robust”, we mean that it must still ensure reachability even when the delays are perturbed by the environment. We model this perturbed semantics as a game between the controller and its environment, and solve the parameterized robust reachability problem: we show that the existence of an upper bound on the perturbations under which there is a strategy reaching a target location is EXPTIMEcomplete. 1
Enhancing the inverse method with state merging
 In NFM, volume 7226 of LNCS
, 2012
"... Abstract. Keeping the state space small is essential when verifying realtime systems using Timed Automata (TA). In the modelchecker Uppaal, the merging operation has been used extensively in order to reduce the number of states. Actually, Uppaal’s merging technique applies within the more general s ..."
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Cited by 4 (2 self)
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Abstract. Keeping the state space small is essential when verifying realtime systems using Timed Automata (TA). In the modelchecker Uppaal, the merging operation has been used extensively in order to reduce the number of states. Actually, Uppaal’s merging technique applies within the more general setting of Parametric Timed Automata (PTA). The Inverse Method (IM) for a PTA A is a procedure that synthesizes a zone around a given point π 0 (parameter valuation) over which A is guaranteed to behave in an equivalent timeabstract manner. We show that the integration of merging into IM leads to the synthesis of larger zones around π 0. It also often improves the performance of IM, both in terms of computational space and time, as shown by our experimental results. 1
Distributed Behavioral Cartography of Timed Automata ∗ †
"... Realtime systems, characterized by a set of timings constants (internal delays, timers, clock speeds), need to be perfectly reliable. Formal methods can prove their correctness but, if one of the timing constants changes, verification needs to be restarted from scratch. Also, variations of some ..."
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Cited by 3 (2 self)
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Realtime systems, characterized by a set of timings constants (internal delays, timers, clock speeds), need to be perfectly reliable. Formal methods can prove their correctness but, if one of the timing constants changes, verification needs to be restarted from scratch. Also, variations of some delays (even infinitesimal) may lead to the specification violation. It is thus interesting to reason parametrically, and synthesize constraints on the timing constants seen as parameters to formally guarantee the specification. We propose here an attempt to distribute a synthesis algorithm, the behavioral cartography, and we evaluate two work distribution algorithms. The parallelization gives promising results and opens perspectives toward verification of larger models.
Robust controller synthesis in timed automata. Research Report LSV1308, Laboratoire Specification et Verification,
, 2013
"... Abstract. We consider the fundamental problem of Büchi acceptance in timed automata in a robust setting. The problem is formalised in terms of controller synthesis: timed automata are equipped with a parametrised gamebased semantics that models the possible perturbations of the decisions taken by ..."
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Abstract. We consider the fundamental problem of Büchi acceptance in timed automata in a robust setting. The problem is formalised in terms of controller synthesis: timed automata are equipped with a parametrised gamebased semantics that models the possible perturbations of the decisions taken by the controller. We characterise timed automata that are robustly controllable for some parameter, with a simple graph theoretic condition, by showing the equivalence with the existence of an aperiodic lasso that satisfies the winning condition (aperiodicity was defined and used earlier in different contexts to characterise convergence phenomena in timed automata). We then show decidability and PSPACEcompleteness of our problem.
What's Decidable About Parametric Timed Automata?
, 2015
"... Context: Model checking (1/2) Need for early bug detection ..."
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Rennes IMITATOR Tutorial Parametric Timed Systems
, 2015
"... Context: Verifying critical realtime systems Need for early bug detection Bugs discovered when final testing: expensive; Need for a thorough specification and verification phase ..."
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Context: Verifying critical realtime systems Need for early bug detection Bugs discovered when final testing: expensive; Need for a thorough specification and verification phase
Beyond Model Checking: Parameter Synthesis
, 2015
"... Timed systems are characterized by a set of timing constants The packet transmission lasts for 50ms The sensor reads the value every 10 s ..."
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Timed systems are characterized by a set of timing constants The packet transmission lasts for 50ms The sensor reads the value every 10 s
Robust Reachability in Timed Automata and Games: A Gamebased Approach I
"... Reachability checking is one of the most basic problems in verification. By solving this problem in a game, one can synthesize a strategy that dictates the actions to be performed for ensuring that the target location is reached. In this work, we are interested in synthesizing “robust ” strategies f ..."
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Reachability checking is one of the most basic problems in verification. By solving this problem in a game, one can synthesize a strategy that dictates the actions to be performed for ensuring that the target location is reached. In this work, we are interested in synthesizing “robust ” strategies for ensuring reachability of a location in timed automata. By robust, we mean that it must still ensure reachability even when the delays are perturbed by the environment. We model this perturbed semantics as a game between the controller and its environment, and solve the parameterized robust reachability problem: we show that the existence of an upper bound on the perturbations under which there is a strategy reaching a target location is EXPTIMEcomplete. We also extend our algorithm, with the same complexity, to turnbased timed games, where the successor state is entirely determined by the environment in some locations. 1.