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73
Interface Automata
 Proceedings of the Ninth Annual Symposium on Foundations of Software Engineering (FSE), ACM
, 2001
"... Conventional type systems specify interfaces in terms of values and domains. ..."
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Cited by 338 (22 self)
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Conventional type systems specify interfaces in terms of values and domains.
Fast Algorithms for Finding Randomized Strategies in Game Trees
, 1994
"... Interactions among agents can be conveniently described by game trees. In order to analyze a game, it is important to derive optimal (or equilibrium) strategies for the different players. The standard approach to finding such strategies in games with imperfect information is, in general, computation ..."
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Cited by 92 (11 self)
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Interactions among agents can be conveniently described by game trees. In order to analyze a game, it is important to derive optimal (or equilibrium) strategies for the different players. The standard approach to finding such strategies in games with imperfect information is, in general, computationally intractable. The approach is to generate the normal form of the game (the matrix containing the payoff for each strategy combination), and then solve a linear program (LP) or a linear complementarity problem (LCP). The size of the normal form, however, is typically exponential in the size of the game tree, thus making this method impractical in all but the simplest cases. This paper describes a new representation of strategies which results in a practical linear formulation of the problem of twoplayer games with perfect recall (i.e., games where players never forget anything, which is a standard assumption). Standard LP or LCP solvers can then be applied to find optimal randomized strategies. The resulting algorithms are, in general, exponentially better than the standard ones, both in terms of time and in terms of space.
Black box checking
 In FORTE/PSTV
, 1999
"... Even if access to the internal structure of the tested system is possible, it is not always a good idea to use it when performing tests, as this may lead to a bias in the testing process. Furthermore, the ..."
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Cited by 42 (1 self)
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Even if access to the internal structure of the tested system is possible, it is not always a good idea to use it when performing tests, as this may lead to a bias in the testing process. Furthermore, the
Module checking revisited
 In Proc. 9th CAV, LNCS 1254
, 1997
"... Abstract. When we verify the correctness of an open system with respect to a desired requirement, we should take into consideration the different environments with which the system may interact. Each environment induces a different behavior of the system, and we want all these behaviors to satisfy t ..."
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Cited by 32 (6 self)
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Abstract. When we verify the correctness of an open system with respect to a desired requirement, we should take into consideration the different environments with which the system may interact. Each environment induces a different behavior of the system, and we want all these behaviors to satisfy the requirement. Module checking is an algorithmic method that checks, given an open system (modeled as a finite structure) and a desired requirement (specified by a temporallogic formula), whether the open system satisfies the requirement with respect to all environments. In this paper we extend the modulechecking method with respect to two orthogonal issues. Both issues concern the fact that often we are not interested in satisfaction of the requirement with respect to all environments, but only with respect to these that meet some restriction. We consider the case where the environment has incomplete information about the system; i.e., when the system has internal variables, which are not readable by its environment, and the case where some assumptions are known about environment; i.e., when the system is guaranteed to satisfy the requirement only when its environment satisfies certain assumptions. We study the complexities of the extended modulechecking problems. In particular, we show that for universal temporal logics (e.g., LTL, ¥ CTL, and ¥ CTL ¦), module checking with incomplete information coincides with module checking, which by itself coincides with model checking. On the other hand, for nonuniversal temporal logics (e.g., CTL and CTL ¦), module checking with incomplete information is harder than module checking, which is by itself harder than model checking. 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 32 (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.
Antichains: A new algorithm for checking universality of finite automata
 In Proc. of CAV 2006, LNCS 4144
, 2006
"... Abstract. We propose and evaluate a new algorithm for checking the universality of nondeterministic finite automata. In contrast to the standard algorithm, which uses the subset construction to explicitly determinize the automaton, we keep the determinization step implicit. Our algorithm computes th ..."
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Cited by 31 (14 self)
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Abstract. We propose and evaluate a new algorithm for checking the universality of nondeterministic finite automata. In contrast to the standard algorithm, which uses the subset construction to explicitly determinize the automaton, we keep the determinization step implicit. Our algorithm computes the least fixed point of a monotone function on the lattice of antichains of state sets. We evaluate the performance of our algorithm experimentally using the random automaton model recently proposed by Tabakov and Vardi. We show that on the difficult instances of this probabilistic model, the antichain algorithm outperforms the standard one by several orders of magnitude. We also show how variations of the antichain method can be used for solving the languageinclusion problem for nondeterministic finite automata, and the emptiness problem for alternating finite automata. 1
On Decision Problems for Probabilistic Büchi Automata
, 2008
"... Probabilistic Büchi automata (PBA) are finitestate acceptors for infinite words where all choices are resolved by fixed distributions and where the accepted language is defined by the requirement that the measure of the accepting runs is positive. The main contribution of this paper is a complement ..."
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Cited by 22 (6 self)
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Probabilistic Büchi automata (PBA) are finitestate acceptors for infinite words where all choices are resolved by fixed distributions and where the accepted language is defined by the requirement that the measure of the accepting runs is positive. The main contribution of this paper is a complementation operator for PBA and a discussion on several algorithmic problems for PBA. All interesting problems, such as checking emptiness or equivalence for PBA or checking whether a finite transition system satisfies a PBAspecification, turn out to be undecidable. An important consequence of these results are several undecidability results for stochastic games with incomplete information, modelled by partiallyobservable Markov decision processes and ωregular winning objectives. Furthermore, we discuss an alternative semantics for PBA where it is required that almost all runs for an accepted word are accepting, which turns out to be less powerful, but has a decidable emptiness problem.
A GameTheoretic Classification of Interactive Complexity Classes (Extended Abstract)
 IN PROCEEDINGS OF THE TENTH ANNUAL IEEE CONFERENCE ON COMPUTATIONAL COMPLEXITY
, 1995
"... Gametheoretic characterizations of complexity classes have often proved useful in understanding the power and limitations of these classes. One wellknown example tells us that PSPACE can be characterized by twoperson, perfectinformation games in which the length of a played game is polynomial i ..."
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Cited by 20 (1 self)
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Gametheoretic characterizations of complexity classes have often proved useful in understanding the power and limitations of these classes. One wellknown example tells us that PSPACE can be characterized by twoperson, perfectinformation games in which the length of a played game is polynomial in the length of the description of the initial position [Chandra et al., Journal of the ACM, 28 (1981), pp. 114133]. In this paper, we investigate the connection between game theory and interactive computation. We formalize the notion of a polynomially definable game system for the language L, which, informally, consists of two arbitrarily powerful players P 1 and P 2 and a ...
The Logic of Distributed Protocols
 THEORETICAL ASPECTS OF REASONING ABOUT KNOWLEDGE: PROC. 1986 CONFERENCE
, 1986
"... A propositional logic of distributed protocols is introduced which includes both the logic of knowledge and temporal logic. Phenomena in distributed computing systems such as asynchronous time, incomplete knowledge by the computing agents in the system, and gamelike behavior among the computing ..."
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Cited by 19 (0 self)
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A propositional logic of distributed protocols is introduced which includes both the logic of knowledge and temporal logic. Phenomena in distributed computing systems such as asynchronous time, incomplete knowledge by the computing agents in the system, and gamelike behavior among the computing agents are all modeled in the logic. Two versions of the logic, the linear logic of protocols (LLP) and the tree logic of protocols (TLP) are investigated. The main result is that the set of valid formulas in LLP is undecidable.