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Verification, Model Checking, and Abstract Interpretation, Third International Workshop, VMCAI 2002, Venice, Italy, January 21-22, 2002, Revised Papers; 01/2002
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Abstraction, Reformulation and Approximation, 5th International Symposium, SARA 2002, Kananaskis, Alberta, Canada, August 2-4, 2002, Proceedings; 01/2002
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ABSTRACT: Symbolic forward analysis is a semi-algorithm that in many cases solves the model checking problem for infinite state systems
in practice. This semi-algorithm is implemented in many practical model checking tools like UPPAAL [BLL+96], KRONOS [DT98] and HYTECH [HHWT97]. In most practical experiments, termination of symbolic forward analysis is achieved by employing abstractions resulting
in an abstract symbolic forward analysis. This paper presents a unified algebraic framework for deriving and reasoning about
abstract symbolic forward analysis procedures for a large class of infinite state systems with variables ranging over a numeric
domain. The framework is obtained by lifting notions from classical algebraic theory of automata to constraints representing
sets of states. Our framework provides sufficient conditions under which the derived abstract symbolic forward analysis procedure
is always terminating or accurate or both. The class of infinite state systems that we consider here are (possibly non-linear)
hybrid systems and (possibly non-linear) integer-valued systems. The central notions involved are those of constraint transformer monoids and coverings between constraint transformer monoids. We show concrete applications of our framework in deriving abstract symbolic forward
analysis algorithms for timed automata and the two process bakery algorithm that are both terminating and accurate.
12/2001: pages 152-169;
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ABSTRACT: Existing model checking tools for infinite state systems, such as UPPAAL, HYTECH and KRONOS, use symbolic forward analysis,
a possibly nonterminating procedure. We give termination criteria that allow us to reason compositionally about systems defined
with asynchronous parallel composition; we can prove the termination of symbolic forward analysis for a composed system from
the syntactic conditions satisfied by the component systems.
Our results apply to nonlinear hybrid systems; in particular to rectangular hybrid systems, timed automata and o-minimal systems.
In the case of integer-valued systems we give negative results: forward analysis is not well-suited for this class of infinite-state
systems.
12/2001: pages 251-255;
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ABSTRACT: We settle the complexity bounds of the model checking problem for the replication-free ambient calculus with public names against the ambient logic without parallel adjunct. We show that the problem is PSPACEcomplete. For the complexity upper-bound, we devise a new representation of processes that remains of polynomial size during process execution; this allows us to keep the model checking procedure in polynomial space. Moreover, we prove PSPACE-hardness of the problem for several quite simple fragments of the calculus and the logic; this suggests that there are no interesting fragments with polynomial-time model checking algorithms. Contents 1
07/2001;
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ABSTRACT: . Theoretical investigations of innite-state systems have so far concentrated on decidability results; in the case of timed automata these results are based on region graphs. We investigate the specic procedure that is used practically in order to decide verication problems, namely symbolic forward analysis. This procedure is possibly nonterminating. We present basic concepts and properties that are useful for reasoning about sucient termination conditions, and then derive some conditions. The central notions here are constraint transformers associated with sequences of automaton edges and zone trees labeled with successor constraints. 1 Introduction A timed automaton [AD94] models a system whose transitions between nitely many control locations depend on the values of clocks. The clocks advance continuously over time; they can individually be reset to the value 0. Since the clocks take values over reals, the state space of a timed automaton is innite. The theoretical ...
02/2001;
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ABSTRACT: We use programming language technology to derive model checking algorithms for Safe Temporal Logic (STL) properties. We express STL properties in terms of the perfect model semantics for stratified constraint logic programs. We present a tabled-resolution procedure for computing the semantics. That procedure translates to the first symbolic forward model checking procedure for STL properties of infinite-state systems.
02/2001;
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Foundations of Software Science and Computation Structures, 4th International Conference, FOSSACS 2001 Held as Part of the Joint European Conferences on Theory and Practice of Software, ETAPS 2001 Genova, Italy, April 2-6, 2001, Proceedings; 01/2001
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ABSTRACT: Some symbolic model checking procedures use disjunctive constraints (e.g. disjunctions of conjunctions of arithmetic inequalities) to represent sets of states. This motivates us to introduce a new class of temporal properties with a backward analysis and a forward analysis that are both well-suited for disjunctive constraints as the `symbolic' data structure. The stratified µ-calculus S is a natural generalization of STL (Safe Temporal Logic) and can be used to express e.g. convergence for timed automata. Our technical contribution is the novel `symbolic forward analysis' method for checking S formulas. This method is based on our characterization of S properties as perfect models of constraint logic programs and on our tabled-resolution procedure for constraint logic programs with the perfect-model semantics.
10/2000;
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ABSTRACT: First, we introduce stratified timed logic processes (STLP's) for modeling stratified or hierarchical real time systems. Second, we present an algorithm for detecting convergence of real time systems by reducing the problem to that of computing model theoretic semantics of stratified timed logic processes. Third, we define formally a notion of transience for real time systems characterizing the transient behavior of such systems. We also present an algorithm for detecting whether a real time system has a transient behavior.
08/1999;
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ABSTRACT: We propose a symbolic model checking procedure for timed systems that is based on operations on constraints. To accelerate the termination of the model checking procedure, we define history-dependent widening operators, again in terms of constraint operations. We show that these widenings are accurate, i.e., they don't lose precision with respect to the test of safety properties.
08/1999;
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ABSTRACT: We introduce Timed Logic Processes (TLP's) for modeling timed systems. We establish their formal connection with the standard model of timed automata. We use this connection to explain the industrial-scale timed model checker UPPAAL in terms of XSB-style tabling with constraints. This allows us (1) to directly obtain a competitive implemention of the corresponding model checking procedure in the CLP system of Sicstus Prolog, (2) to enforce termination through an operation on constraints, and (3) to increase the expressiveness of the underlying timed temporal logic.
06/1999;
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ABSTRACT: Brand and Zafiropulo [BZ83] introduced the model of communicating finite-state machines to represent a distributed system connected with FIFO channels. Several different communication protocols can be specified with this simple model. In this paper we address the problem of automatically validating protocols by verifying properties such as well-formedness and absence of deadlock. Our method is based on a representation of communicating finite-state machines in terms of logic programs. This leads to efficient verification algorithms based on the ground and non-ground semantics of logic programming, 1 Introduction Formal methods of specification and analysis are a way to handle the increasing complexity of communication protocols. For this purpose, in [Boc78], Bochmann introduced the model of communicating finite-state machines (CFSMs) to represent a distributed system connected with FIFO channels (i.e.queues). Many communication protocols can be specified within this simple mode...
10/1998;
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ABSTRACT: We settle the complexity bounds of the model checking problem for the ambient calculus with public names against the ambient logic. We show that if either the calculus contains replication or the logic contains the guarantee operator, the problem is undecidable. In the case of the replication-free calculus and guarantee-free logic we prove that the problem is PSPACE-complete. For the complexity upper bound, we devise a new representation of processes that remains of polynomial size during process execution; this allows us to keep the model checking procedure in polynomial space. Moreover, we prove PSPACE-hardness of the problem for several quite simple fragments of the calculus and the logic; this suggests that there are no interesting fragments with polynomial-time model checking algorithms.
Theoretical Computer Science.
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Verification, model checking, and abstract interpretation : 4th International Conference, VMCAI 2003, Springer, 1-13 (2003).
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[show abstract]
[hide abstract]
ABSTRACT: We settle the complexity bounds of the model checking problem for the replication-free ambient calculus with public names against the ambient logic without parallel adjunct. We show that the problem is PSPACE-complete. For the complexity upper-bound, we devise a new representation of processes that remains of polynomial size during process execution; this allows us to keep the model checking procedure in polynomial space. Moreover, we prove PSPACE-hardness of the problem for several quite simple fragments of the calculus and the logic; this suggests that there are no interesting fragments with polynomial-time model checking algorithms.
Honsell, Furio; Miculan, Marino: Foundations of Software Science and Computation Structures. Proceedings of the 4th International Conference (FOSSACS-01). Held as Part of the Joint European Conferences on Theory and Practice of Software (ETAPS-01), Springer, 152-167 (2001).
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Abstraction, reformulation, and approximation : 5th International Symposium, SARA 2002, Springer, 152-169 (2002).
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ABSTRACT: Forward analysis procedures for infinite-state systems such as timed systems were limited to safety properties. We give the first constraint-based forward analysis for infinite-state systems that goes beyond safety properties. Namely, we take the restriction of the $\mu$-calculus to least-fixpoint formulas where negation is applied to closed subformulas only. We characterize these properties as perfect models of constraint logic programs, and we present a tabulation procedure for the top-down evaluation of stratified constraint logic programs.
Logic Programming. 18th International Conference, ICLP 2002, Springer, 115-129 (2002).
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Pacholski, Leszek; Ruzicka, Peter: Proceedings of the 28th Annual Conference on Current Trends in Theory and Practice of Informatics (SOFSEM-2001), Springer, 160-170 (2001).
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Zamulin, Alexandre; Broy, Manfred; Bjorner, Dines: Perspectives of System Informatics: 4th International Andrei Ershov Memorial Conference, Springer, 79-94 (2001).
