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Alternatingtime Temporal Logic
 Journal of the ACM
, 1997
"... Temporal logic comes in two varieties: lineartime temporal logic assumes implicit universal quantification over all paths that are generated by system moves; branchingtime temporal logic allows explicit existential and universal quantification over all paths. We introduce a third, more general var ..."
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Cited by 477 (48 self)
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Temporal logic comes in two varieties: lineartime temporal logic assumes implicit universal quantification over all paths that are generated by system moves; branchingtime temporal logic allows explicit existential and universal quantification over all paths. We introduce a third, more general variety of temporal logic: alternatingtime temporal logic offers selective quantification over those paths that are possible outcomes of games, such as the game in which the system and the environment alternate moves. While lineartime and branchingtime logics are natural specification languages for closed systems, alternatingtime logics are natural specification languages for open systems. For example, by preceding the temporal operator "eventually" with a selective path quantifier, we can specify that in the game between the system and the environment, the system has a strategy to reach a certain state. Also the problems of receptiveness, realizability, and controllability can be formulated as modelchecking problems for alternatingtime formulas.
On the Synthesis of Discrete Controllers for Timed Systems
 in E.W. Mayr and C. Puech (Eds), Proc. STACS'95, LNCS 900
, 1995
"... Abstract. This paper presents algorithms for the automatic synthesis of realtime controllers by nding a winning strategy for certain games de ned by the timedautomata of Alur and Dill. In such games, the outcome depends on the players ' actions as well as on their timing. We believe that thes ..."
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Cited by 201 (20 self)
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Abstract. This paper presents algorithms for the automatic synthesis of realtime controllers by nding a winning strategy for certain games de ned by the timedautomata of Alur and Dill. In such games, the outcome depends on the players ' actions as well as on their timing. We believe that these results will pave theway for the application of program synthesis techniques to the construction of realtime embedded systems from their speci cations. 1
CONTROLLER SYNTHESIS FOR TIMED AUTOMATA
"... In this work we tackle the following problem: given a timed automaton, restrict its transition relation in a systematic way so that all the remaining behaviors satisfy certain properties. This is an extension of the problem of controller synthesis for discrete event dynamical systems, where in addi ..."
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Cited by 123 (15 self)
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In this work we tackle the following problem: given a timed automaton, restrict its transition relation in a systematic way so that all the remaining behaviors satisfy certain properties. This is an extension of the problem of controller synthesis for discrete event dynamical systems, where in addition to choosing among actions, the controller have the option of doing nothing and let the time pass. The problem is formulated using the notion of a realtime game, and a winning strategy is constructed as a fixedpoint of an operator on the space of states and clock configurations.
Effective Synthesis of Switching Controllers for Linear Systems
, 2000
"... In this work we suggest a novel methodology for synthesizing switching controllers for continuous and hybrid systems whose dynamics are defined by linear differential equations. We formulate the synthesis problem as finding the conditions upon which a controller should switch the behavior of the sys ..."
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Cited by 80 (8 self)
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In this work we suggest a novel methodology for synthesizing switching controllers for continuous and hybrid systems whose dynamics are defined by linear differential equations. We formulate the synthesis problem as finding the conditions upon which a controller should switch the behavior of the system from one "mode" to another in order to avoid a set of bad states, and propose an abstract algorithm which solves the problem by an iterative computation of reachable states. We have implemented a concrete version of the algorithm, which uses a new approximation scheme for reachability analysis of linear systems.
A survey of Petri nets methods for controlled discrete event systems. Discrete Event Dynamic Systems: Theory and Applications
, 1997
"... Abstract. This paper surveys recent research on the application of Petri net models to the analysis and synthesis of controllers for discrete event systems. Petri nets have been used extensively in applications such as automated manufacturing, and there exists a large body of tools for qualitative a ..."
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Cited by 64 (2 self)
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Abstract. This paper surveys recent research on the application of Petri net models to the analysis and synthesis of controllers for discrete event systems. Petri nets have been used extensively in applications such as automated manufacturing, and there exists a large body of tools for qualitative and quantitative analysis of Petri nets. The goal of Petri net research in discrete event systems is to exploit the structural properties of Petri net models in computationally efficient algorithms for computing controls. We present an overview of the various models and problems formulated in the literature focusing on two particular models, the controlled Petri nets and the labeled nets. We describe two basic approaches for controller synthesis, based on state feedback and event feedback. We also discuss two efficient techniques for the online computation of the control law, namely the linear integer programming approach which takes advantage of the linear structure of the Petri net state transition equation, and pathbased algorithms which take advantage of the graphical structure of Petri net models. Extensions to timed models are briefly described. The paper concludes with a discussion of directions for future research.
An Implementation of Three Algorithms for Timing Verification Based on Automata Emptiness
, 1992
"... This papers describes modifications to and the implementation of algorithms previously described in [1, 11]. We first describe three generic (untimed) algorithms for constructing graphs of the reachable states of a system, and how these graphs can be used for verification. They all have as input an ..."
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Cited by 59 (3 self)
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This papers describes modifications to and the implementation of algorithms previously described in [1, 11]. We first describe three generic (untimed) algorithms for constructing graphs of the reachable states of a system, and how these graphs can be used for verification. They all have as input an implicit description of a transition system. We then apply these algorithms to realtime systems. The first algorithm performs a straightforward reachability analysis on sets of states of the system, rather than on individual states. This corresponds to stepping symbolically through the system many states at a time. In the case of a realtime system this procedure constructs a graph where each node is the union of some regions of the regions graph. There is therefore no need for an a priori partitioning of the state space into individual regions; however, this approach potentially leads to exponentially worse complexity since its potential state space is the power set of regions [1]. The other two algorithms we consider are minimization algorithms [12, 13, 11]. These simultaneously perform reachability analysis and minimization from an implicit system description. These can lead to great savings when the minimized graph is much smaller than the explicit reachable graph. Our paradigm for verification is to test for the emptiness of the set of all timed system executions that violate a requirements specification. One way to specify and verify nonterminating processes is to model them as languages of !sequences of events [14, 15, 16, 1, 17, 18]. Modular processes can be constructed via composition operations involving language intersection. Specifications are also given as languages: they contain all acceptable event sequences. Program correctness is then just language contain...
JobShop Scheduling using Timed Automata
, 2001
"... . In this paper we show how the classical jobshop scheduling problem can be modeled as a special class of acyclic timed automata. Finding an optimal schedule corresponds, then, to finding a shortest (in terms of elapsed time) path in the timed automaton. This representation provides new techniq ..."
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Cited by 44 (8 self)
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. In this paper we show how the classical jobshop scheduling problem can be modeled as a special class of acyclic timed automata. Finding an optimal schedule corresponds, then, to finding a shortest (in terms of elapsed time) path in the timed automaton. This representation provides new techniques for solving the optimization problem and, more importantly, it allows to model naturally more complex dynamic resource allocation problems which are not captured so easily in traditional models of operation research. We present several algorithms and heuristics for finding the shortest paths in timed automata and test their implementation in the tool Kronos on numerous benchmark examples. 1
Timed Control with Partial Observability
, 2003
"... We consider the problem of synthesizing controllers for timed systems modeled using timed automata. The point of departure from earlier work is that we consider controllers that have only a partial observation of the system that it controls. In discrete event systems (where continuous time is not ..."
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Cited by 37 (6 self)
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We consider the problem of synthesizing controllers for timed systems modeled using timed automata. The point of departure from earlier work is that we consider controllers that have only a partial observation of the system that it controls. In discrete event systems (where continuous time is not modeled), it is well known how to handle partial observability, and decidability issues do not differ from the complete information setting. We show however that timed control under partial observability is undecidable even for internal specifications (while the analogous problem under complete observability is decidable) and we identify a decidable subclass.
Decomposition and Composition of Timed Automata
, 1999
"... We propose in this paper a decomposition theorem for the timed automata introduced by Alur and Dill [3,4]. To this purpose, we define a new simple and natural composition operation, indexed by the set of clocks to be reset, on timed automata generalizing the classical untimed concatenation. Then we ..."
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Cited by 14 (4 self)
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We propose in this paper a decomposition theorem for the timed automata introduced by Alur and Dill [3,4]. To this purpose, we define a new simple and natural composition operation, indexed by the set of clocks to be reset, on timed automata generalizing the classical untimed concatenation. Then we extend the famous Kleene's and Büchi's theorems on classical untimed automata by simply changing the basic objects to take time into account, keeping the union operation and replacing the concatenation, finite and infinite iterations by the new timed concatenations and their induced iterations. Thus, and on the contrary of the interesting result of [8], we do not need neither intersection nor renaming. Therefore, and up to our knowledge, our result provides the simplest known algebraic characterization of recognizable timed languages.