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46
Games for synthesis of controllers with partial observation
 THEORETICAL COMPUTER SCIENCE
"... The synthesis of controllers for discrete event systems, as introduced by Ramadge and Wonham, amounts to computing winning strategies in parity games. We show that in this framework it is possible to extend the specifications of the supervised systems as well as the constraints on the controllers ..."
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Cited by 115 (14 self)
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The synthesis of controllers for discrete event systems, as introduced by Ramadge and Wonham, amounts to computing winning strategies in parity games. We show that in this framework it is possible to extend the specifications of the supervised systems as well as the constraints on the controllers by expressing them in the modal µcalculus. In order to express unobservability constraints, we propose an extension of the modal µcalculus in which one can specify whether an edge of a graph is a loop. This extended µcalculus still has the interesting properties of the classical one. In particular it is equivalent to automata with loop testing. The problems such as emptiness testing and elimination of alternation are solvable for such automata. The method proposed in this paper to solve a control problem consists in transforming this problem into a problem of satisfiability of a µcalculus formula so that the set of models of this formula is exactly the set of controllers that solve the problem. This transformation relies on a simple construction of the quotient of automata with loop testing by a deterministic transition system. This is enough to deal with centralized control problems. The solution of decentralized control problems uses a more involved construction of the quotient of two automata. This work extends the framework of Ramadge and Wonham in two directions. We consider infinite behaviours and arbitrary regular specifications, while the standard framework deals only with specifications on the set of finite paths of processes. We also allow dynamic changes of the set of observable and controllable events.
Synthesizing StateBased Object Systems from LSC Specifications
, 2000
"... Live sequence charts (LSCs) have been de ned recently as an extension of message sequence charts (MSCs � or their UML variant, sequence diagrams) for rich interobject speci cation. One of the main additions is the notion of universal charts and hot, mandatory behavior, which, among other things, en ..."
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Cited by 95 (24 self)
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Live sequence charts (LSCs) have been de ned recently as an extension of message sequence charts (MSCs � or their UML variant, sequence diagrams) for rich interobject speci cation. One of the main additions is the notion of universal charts and hot, mandatory behavior, which, among other things, enables one to specify forbidden scenarios. LSCs are thus essentially as expressive as statecharts. This paper deals with synthesis, which is the problem of deciding, given an LSC speci cation, if there exists a satisfying object system and, if so, to synthesize one automatically. The synthesis problem is crucial in the development of complex systems, since sequence diagrams serve as the manifestation of use cases  whether used formally or informally  and if synthesizable they could lead directly to implementation. Synthesis is considerably harder for LSCs than for MSCs, and we tackle it by de ning consistency, showing that an entire LSC speci cation is consistent i it is satis able by a statebased object system, and then synthesizing a satisfying system as a collection of nite state machines or statecharts. 1
Planning as Model Checking for Extended Goals in NonDeterministic Domains
, 2001
"... Recent research has addressed the problem of planning in nondeterministic domains. Classical planning has also been extended to the case of goals that can express temporal properties. However, the combination of these two aspects is not trivial. In nondeterministic domains, goals should take ..."
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Cited by 78 (14 self)
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Recent research has addressed the problem of planning in nondeterministic domains. Classical planning has also been extended to the case of goals that can express temporal properties. However, the combination of these two aspects is not trivial. In nondeterministic domains, goals should take into account the fact that a plan may result in many possible different executions and that some requirements can be enforced on all the possible executions, while others may be enforced only on some executions. In this paper we address this problem.
Smart PlayOut of Behavioral Requirements
 The Weizmann Institute of Science
, 2002
"... We describe a methodology for executing scenariobased requirements of reactive systems, focusing on "playingout" the behavior using formal verification techniques for driving the execution. The methodology is implemented in full in our playengine tool . The approach appears to be useful ..."
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Cited by 66 (42 self)
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We describe a methodology for executing scenariobased requirements of reactive systems, focusing on "playingout" the behavior using formal verification techniques for driving the execution. The methodology is implemented in full in our playengine tool . The approach appears to be useful in many stages in the development of reactive systems, and might also pave the way to systems that are constructed directly from their requirements, without the need for intraobject or intracomponent modeling or coding.
Synthesis of faulttolerant concurrent programs
 Proceedings of the 17th ACM Symposium on Principles of Distributed Computing (PODC
, 1998
"... Methods for mechanically synthesizing concurrent programs from temporal logic specifications obviate the need to manually construct a program and compose a proof of its correctness. A serious drawback of extant synthesis methods, however, is that they produce concurrent programs for models of comput ..."
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Cited by 53 (5 self)
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Methods for mechanically synthesizing concurrent programs from temporal logic specifications obviate the need to manually construct a program and compose a proof of its correctness. A serious drawback of extant synthesis methods, however, is that they produce concurrent programs for models of computation that are often unrealistic. In particular, these methods assume completely faultfree operation, i.e., the programs they produce are faultintolerant. In this paper, we show how to mechanically synthesize faulttolerant concurrent programs for various fault classes. We illustrate our method by synthesizing faulttolerant solutions to the mutual exclusion and barrier synchronization problems. Categories and Subject Descriptors: F.3.1 [Logics and Meanings of Programs]: Specifying and Verifying and Reasoning about Programs—logics of programs, mechanical verification, specification
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 50 (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.
S.: Uniform distributed synthesis
 In: IEEE Symposium on Logic in Computer Science
, 2005
"... We provide a uniform solution to the problem of synthesizing a finitestate distributed system. An instance of the synthesis problem consists of a system architecture and a temporal specification. The architecture is given as a directed graph, where the nodes represent processes (including the en ..."
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Cited by 44 (18 self)
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We provide a uniform solution to the problem of synthesizing a finitestate distributed system. An instance of the synthesis problem consists of a system architecture and a temporal specification. The architecture is given as a directed graph, where the nodes represent processes (including the environment as a special process) that communicate synchronously through shared variables attached to the edges. The same variable may occur on multiple outgoing edges of a single node, allowing for the broadcast of data. A solution to the synthesis problem is a collection of finitestate programs for the processes in the architecture, such that the joint behavior of the programs satisfies the specification in an unrestricted environment. We define information forks, a comprehensive criterion that characterizes all architectures with an undecidable synthesis problem. The criterion is effective: for a given architecture with n processes and v variables, it can be determined in O(n2 · v) time whether the synthesis problem is decidable. We give a uniform synthesis algorithm for all decidable cases. Our algorithm works for all ωregular tree specification languages, including the µcalculus. The undecidability proof, on the other hand, uses only LTL or, alternatively, CTL as the specification language. Our results therefore hold for the entire range of specification languages from LTL/CTL to the µcalculus. 1
STRONG CYCLIC PLANNING REVISITED
"... Several realistic nondeterministic planning domains require plans that encode iterative trialanderror strategies, e.g., "pick up a block until succeed". In such domains, a certain effect (e.g., action success) might never be guaranteed a priori of execution and, in principle, iterative ..."
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Cited by 36 (9 self)
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Several realistic nondeterministic planning domains require plans that encode iterative trialanderror strategies, e.g., "pick up a block until succeed". In such domains, a certain effect (e.g., action success) might never be guaranteed a priori of execution and, in principle, iterative plans might loop forever. Here, the planner should generate iterative plans whose executions always have a possibility of terminating and, when they do, they are guaranteed to achieve the goal. In this paper, we define the notion of strong cyclic plan, which formalizes in temporal logic the above informal requirements for iterative plans, define a planning algorithm based on modelchecking techniques, and prove that the algorithm is guaranteed to return strong cyclic plans when they exist or to terminate with failure when they do not. We show how this approach can be extended to formalize plans that are guaranteed to achieve the goal and do not involve iterations (strong plans) and plans that have a possibility (but are not guaranteed) to achieve the goal (weak plans). The results presented in this paper constitute a formal account for "planning via model checking" in nondeterministic domains, which has never been provided before.
Automatic synthesis of new behaviors from a library of available behaviors
 In Proc. of IJCAI 2007
, 2007
"... We consider the problem of synthesizing a fully controllable target behavior from a set of available partially controllable behaviors that are to execute within a shared partially predictable, but fully observable, environment. Behaviors are represented with a sort of nondeterministic transition sys ..."
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Cited by 33 (14 self)
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We consider the problem of synthesizing a fully controllable target behavior from a set of available partially controllable behaviors that are to execute within a shared partially predictable, but fully observable, environment. Behaviors are represented with a sort of nondeterministic transition systems, whose transitions are conditioned on the current state of the environment, also represented as a nondeterministic finite transition system. On the other hand, the target behavior is assumed to be fully deterministic and stands for the behavior that the system as a whole needs to guarantee. We formally define the problem within an abstract framework, characterize its computational complexity, and propose a solution by appealing to satisfiability in Propositional Dynamic Logic, which is indeed optimal with respect to computational complexity. We claim that this problem, while novel to the best of our knowledge, can be instantiated to multiple specific settings in different contexts and can thus be linked to different research areas of AI, including agentoriented programming and cognitive robotics, control, multiagent coordination, plan integration, and automatic webservice composition. 1