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25
Communicating Hierarchical State Machines
 in 26th International Colloquium on Automata, Languages and Programming (ICALP
, 1999
"... . Hierarchical state machines are finite state machines whose states themselves can be other machines. In spite of their popularity in many modeling tools for software design, very little is known concerning their complexity and expressiveness. In this paper, we study these questions for hierarchica ..."
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Cited by 36 (4 self)
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. Hierarchical state machines are finite state machines whose states themselves can be other machines. In spite of their popularity in many modeling tools for software design, very little is known concerning their complexity and expressiveness. In this paper, we study these questions for hierarchical state machines as well as for communicating hierarchical state machines, that is, finite state machines extended with both hierarchy and concurrency. We present a comprehensive set of results characterizing (1) the complexity of the reachability, emptiness and universality problems, (2) the complexity of the language inclusion and equivalence problems, and (3) the succinctness relationships between different types of machines. 1 Introduction Finite state machines (FSMs) are widely used in the modeling of systems in various areas. Descriptions using FSMs are useful to represent the flow of control (as opposed to data manipulation) and are amenable to formal analysis such as model checking ...
Automatatheoretic approach to planning for temporally extended goals
 IN ECP
, 2000
"... We study an automatatheoretic approach to planning for temporally extended goals. Specifically, we devise techniques based on nonemptiness of Büchi automata on infinite words, to synthesize sequential and conditional plans in a generalized setting in which we have that: goals are general temporal ..."
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Cited by 36 (5 self)
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We study an automatatheoretic approach to planning for temporally extended goals. Specifically, we devise techniques based on nonemptiness of Büchi automata on infinite words, to synthesize sequential and conditional plans in a generalized setting in which we have that: goals are general temporal properties of desired execution; dynamic systems are represented by finite transition systems; incomplete information on the initial situation is allowed; and states are only partially observable. We prove that the techniques proposed are optimal wrt the worst case complexity of the problem. Thanks to the scalability of the nonemptiness algorithms, the techniques presented here promise to be applicable to fairly large systems, notwithstanding the intrinsic complexity of the problem.
Pattern Matching and Membership for Hierarchical Message Sequence Charts
 In Proc. of LATIN 2002, LNCS 2286
, 2002
"... Several formalisms and tools for software development use hierarchy for system design, for instance statecharts and diagrams in UML. Message sequence charts are an ITU standardized notation for asynchronously communicating processes. The standard Z.120 allows (highlevel) MSCreferences that corresp ..."
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Cited by 12 (4 self)
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Several formalisms and tools for software development use hierarchy for system design, for instance statecharts and diagrams in UML. Message sequence charts are an ITU standardized notation for asynchronously communicating processes. The standard Z.120 allows (highlevel) MSCreferences that correspond to the use of macros. We consider in this paper two basic verification tasks for hierarchical MSCs (nested highlevel MSCs, nHMSC), the membership and the pattern matching problem. We show that the membership problem for nHMSCs is PSPACEcomplete, even using a weaker semantics for nMSCs than the partialorder semantics. For pattern matching nMSCs M;N we exhibit a polynomial algorithm of time O(jM j 2 \Delta jN j 2 ). We use here techniques stemming from algorithms on compressed texts.
Modeling and Simulation of Large Biological, Information and SocioTechnical Systems: An Interaction Based Approach
 Interactive Computation: The New
, 2005
"... Summary We describe an interaction based approach for computer modeling and simulation of large integrated biological, information, social and technical (BIST) systems 1 Examples of such systems are urban regional transportation systems, the national electrical power markets and grids, gene regulato ..."
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Cited by 11 (8 self)
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Summary We describe an interaction based approach for computer modeling and simulation of large integrated biological, information, social and technical (BIST) systems 1 Examples of such systems are urban regional transportation systems, the national electrical power markets and grids, gene regulatory networks, the worldwide Internet, infectious diseases, vaccine design and deployment, theater war, etc. These systems are composed of large numbers of interacting human, physical, informational and technological components. These components adapt and learn, exhibit perception, interpretation, reasoning, deception, cooperation and noncooperation, and have economic motives as well as the usual physical properties of interaction. The theoretical foundation of our approach consists of two parts: (i) mathematics of complex interdependent dynamic networks, and (ii) mathematical and computational theory of a class of finite discrete dynamical systems called Sequential Dynamical Systems (SDSs). We then consider engineering principles based on such a theory. As with the theoretical foundation, they consist of two basic parts: (i) Efficient data manipulation, including synthesis, integration, storage and regeneration and (ii) high performance computing oriented system design, development and implementation. The engineering methods allow us to specify, design, and analyze simulations of extremely large systems and implement them on massively parallel architectures. As an illustration of our approach, an interaction based computer modeling and simulation framework to study very large interdependent societal infrastructures is described. 1
Workflows, Transactions, and Datalog
 In Proc. ACM Symposium on Principles of Database Systems (PODS’99
, 1999
"... Transaction Datalog (abbreviated T D) is a concurrent programming language that provides process modeling, database access, and advanced transactions. This paper illustrates the use of T D for specifying and simulating workflows, with examples based on the needs of a highthroughput genome laborator ..."
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Cited by 10 (0 self)
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Transaction Datalog (abbreviated T D) is a concurrent programming language that provides process modeling, database access, and advanced transactions. This paper illustrates the use of T D for specifying and simulating workflows, with examples based on the needs of a highthroughput genome laboratory. In addition to database support, these needs include concurrent access to shared resources, synchronization of work, and networks of cooperating workflows. We also use T D to explore the computational complexity of workflows in dataintensive applications. We show, for instance, that workflows can be vastly more complex than database transactions, largely because concurrent processes can interact and communicate via the database (i:e:, one process can read what another one writes). We then investigate the sources of this complexity, focusing on features for data modeling and process modeling. We show that by carefully controlling these features, the complexity of workflows can be reduced ...
The Complexity of Live Sequence Charts
 In Foundations of Software Science and Computational Structures, 8th International Conference, FOSSACS 2005
, 2005
"... ..."
Robust Satisfaction
, 1999
"... In order to check whether an open system satisfies a desired property, we need to check the behavior of the system with respect to an arbitrary environment. In the most general setting, the environment is another open system. Given an open system � and a property � , we say that � robustly satisfie ..."
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Cited by 6 (3 self)
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In order to check whether an open system satisfies a desired property, we need to check the behavior of the system with respect to an arbitrary environment. In the most general setting, the environment is another open system. Given an open system � and a property � , we say that � robustly satisfies � iff for every open system �� � , which serves as an environment to � , the composition ���� � � satisfies �. The problem of robust model checking is then to decide, given � and � , whether � robustly satisfies �. In this paper we study the robustmodelchecking problem. We consider systems modeled by nondeterministic Moore machines, and properties specified by branching temporal logic (for linear temporal logic, robust satisfaction coincides with usual satisfaction). We show that the complexity of the problem is EXPTIMEcomplete for CTL and the �calculus, and is 2EXPTIMEcomplete for CTL �. We partition branching temporal logic formulas into three classes: universal, existential, and mixed formulas. We show that each class has different sensitivity to the robustness requirement. In particular, unless the formula is mixed, robust model checking can ignore nondeterministic environments. In addition, we show that the problem of classifying a CTL formula into these classes is EXPTIMEcomplete.
Treewidth in Verification: Local vs. Global
 In LPAR 2005
, 2005
"... this paper concurrent transition systems, where communication between concurrent components is modeled explicitly. Assuming boundedness of the treewidth of the communication graph, which we refer to as local treewidth, is reasonable, since the topology of communication in concurrent systems is oft ..."
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Cited by 6 (2 self)
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this paper concurrent transition systems, where communication between concurrent components is modeled explicitly. Assuming boundedness of the treewidth of the communication graph, which we refer to as local treewidth, is reasonable, since the topology of communication in concurrent systems is often constrained physically
Improved Model Checking of Hierarchical Systems
, 2009
"... We present a unified gamebased approach for branchingtime model checking of hierarchical systems. Such systems are exponentially more succinct than standard statetransition graphs, as repeated subsystems are described only once. Early work on model checking of hierarchical systems shows that one ..."
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Cited by 6 (3 self)
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We present a unified gamebased approach for branchingtime model checking of hierarchical systems. Such systems are exponentially more succinct than standard statetransition graphs, as repeated subsystems are described only once. Early work on model checking of hierarchical systems shows that one can do better than a naive algorithm that “flattens ” the system and removes the hierarchy. Given a hierarchical system S and a branchingtime specification ψ for it, we reduce the modelchecking problem (does S satisfy ψ?) to the problem of solving a hierarchical game obtained by taking the product of S with an alternating tree automaton Aψ for ψ. Our approach leads to clean, uniform, and improved modelchecking algorithms for a variety of branchingtime temporal logics. In particular, by improving the algorithm for solving hierarchical parity games, we are able to solve the modelchecking problem for the µcalculus in Pspace and time complexity that is only polynomial in the depth of the hierarchy. Our approach also leads to an abstractionrefinement paradigm for hierarchical systems. The abstraction maintains the hierarchy, and is obtained by merging both states and subsystems into abstract states.
Science and Engineering of Large Scale SocioTechnical Simulations
 Proceedings of the 1st International Conference on Grand Challenges in Simulations, held as part of the Western Simulation Conference
, 2002
"... Computer simulation is a computational approach whereby global system properties are produced as dynamics by direct computation of interactions among representations of local system elements. A mathematical theory of simulation consists of an account of the formal properties of sequential evaluation ..."
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Cited by 3 (2 self)
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Computer simulation is a computational approach whereby global system properties are produced as dynamics by direct computation of interactions among representations of local system elements. A mathematical theory of simulation consists of an account of the formal properties of sequential evaluation and composition of interdependent local mappings. When certain local mappings and their interdependencies can be related to particular real world objects and interdependencies, it is common to compute the interactions to derive a symbolic model of the global system made up of the corresponding interdependent objects. The formal mathematical and computational account of the simulation provides a particular kind of theoretical explanation of the global system properties and, therefore, insight into how to engineer a complex system to exhibit those properties. This paper considers the mathematical foundations and engineering principles necessary for building large scale simulations of sociotechnical systems. Examples of such systems are urban regional transportation systems, the national electrical power markets and grid, the worldwide Internet, vaccine design and deployment, theater war, etc. These systems are composed of large numbers of interacting human, physical and technological components. Some components adapt and learn, exhibit perception, interpretation, reasoning, deception, cooperation and noncooperation, and economic motives as well as the usual physical properties of interaction. The systems themselves are large and the behavior of sociotechnical systems is tremendously complex.