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74
A theory of timed automata
, 1999
"... Model checking is emerging as a practical tool for automated debugging of complex reactive systems such as embedded controllers and network protocols (see [23] for a survey). Traditional techniques for model checking do not admit an explicit modeling of time, and are thus, unsuitable for analysis of ..."
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Cited by 2651 (32 self)
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Model checking is emerging as a practical tool for automated debugging of complex reactive systems such as embedded controllers and network protocols (see [23] for a survey). Traditional techniques for model checking do not admit an explicit modeling of time, and are thus, unsuitable for analysis of realtime systems whose correctness depends on relative magnitudes of different delays. Consequently, timed automata [7] were introduced as a formal notation to model the behavior of realtime systems. Its definition provides a simple way to annotate statetransition graphs with timing constraints using finitely many realvalued clock variables. Automated analysis of timed automata relies on the construction of a finite quotient of the infinite space of clock valuations. Over the years, the formalism has been extensively studied leading to many results establishing connections to circuits and logic, and much progress has been made in developing verification algorithms, heuristics, and tools. This paper provides a survey of the theory of timed automata, and their role in specification and verification of realtime systems.
A tutorial on uppaal
, 2004
"... This is a tutorial paper on the tool Uppaal. Its goal is to be a short introduction on the flavor of timed automata implemented in the tool, to present its interface, and to explain how to use the tool. The contribution of the paper is to provide reference examples and modeling patterns. ..."
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Cited by 311 (19 self)
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This is a tutorial paper on the tool Uppaal. Its goal is to be a short introduction on the flavor of timed automata implemented in the tool, to present its interface, and to explain how to use the tool. The contribution of the paper is to provide reference examples and modeling patterns.
Timed automata: Semantics, algorithms and tools
 Lectures on Concurrency and Petri Nets: Advances in Petri Nets, number 3098 in LNCS
, 2004
"... Abstract. This chapter is to provide a tutorial and pointers to results and related work on timed automata with a focus on semantical and algorithmic aspects of verification tools. We present the concrete and abstract semantics of timed automata (based on transition rules, regions and zones), decisi ..."
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Cited by 171 (4 self)
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Abstract. This chapter is to provide a tutorial and pointers to results and related work on timed automata with a focus on semantical and algorithmic aspects of verification tools. We present the concrete and abstract semantics of timed automata (based on transition rules, regions and zones), decision problems, and algorithms for verification. A detailed description on DBM (Difference Bound Matrices) is included, which is the central data structure behind several verification tools for timed systems. As an example, we give a brief introduction to the tool UPPAAL. 1
Timed petri nets and BQOs
 In Proc. ICATPN’01
, 2001
"... Abstract. We consider (unbounded) Timed Petri Nets (TPNs) where each token is equipped with a realvalued clock representing the “age” of the token. Each arc in the net is provided with a subinterval of the natural numbers, restricting the ages of the tokens travelling the arc. We apply a methodolog ..."
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Cited by 61 (9 self)
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Abstract. We consider (unbounded) Timed Petri Nets (TPNs) where each token is equipped with a realvalued clock representing the “age” of the token. Each arc in the net is provided with a subinterval of the natural numbers, restricting the ages of the tokens travelling the arc. We apply a methodology developed in [AN00], based on the theory of better quasi orderings (BQOs), to derive an efficient constraint system for automatic verification of safety properties for TPNs. We have implemented a prototype based on our method and applied it for verification of a parametrized version of Fischer’s protocol. 1
The octahedron abstract domain
 In Static Analysis Symposium (2004
, 2004
"... NOTICE: This is the author’s version of a work that was accepted for publication in Science of Computer Programming. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this docu ..."
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Cited by 58 (1 self)
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NOTICE: This is the author’s version of a work that was accepted for publication in Science of Computer Programming. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. A definitive version was subsequently published in Science of Computer Programming, 64(2007):115139.
Difference decision diagrams
 University of Copenhagen
, 1999
"... This paper describes a new data structure, difference decision diagrams (DDDs), for representing a Boolean logic over inequalities of the form ¡£¢¥¤§¦© ¨ and ¡�¢¥¤���¨ where the variables are integer or realvalued. We give algorithms for manipulating DDDs and for determining functional properties ( ..."
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Cited by 51 (2 self)
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This paper describes a new data structure, difference decision diagrams (DDDs), for representing a Boolean logic over inequalities of the form ¡£¢¥¤§¦© ¨ and ¡�¢¥¤���¨ where the variables are integer or realvalued. We give algorithms for manipulating DDDs and for determining functional properties (tautology, satisfiability, and equivalence). DDDs enable an efficient verification of timed systems modeled as, for example, timed automata or timed Petri nets, since both the states and their associated timing information can be represented symbolically, similar to how ROBDDs represent Boolean predicates.
Binary Reachability Analysis of Discrete Pushdown Timed Automata
 CAV'00, LNCS 1855
, 2000
"... . We introduce discrete pushdown timed automata that are timed automata with integervalued clocks augmented with a pushdown stack. A configuration of a discrete pushdown timed automaton includes a control state, finitely many clock values and a stack word. Using a pure automatatheoretic approa ..."
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Cited by 45 (28 self)
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. We introduce discrete pushdown timed automata that are timed automata with integervalued clocks augmented with a pushdown stack. A configuration of a discrete pushdown timed automaton includes a control state, finitely many clock values and a stack word. Using a pure automatatheoretic approach, we show that the binary reachability (i.e., the set of all pairs of configurations (ff; fi), encoded as strings, such that ff can reach fi through 0 or more transitions) can be accepted by a nondeterministic pushdown machine augmented with reversalbounded counters (NPCM). Since discrete timed automata with integervalued clocks can be treated as discrete pushdown timed automata without the pushdown stack, we can show that the binary reachability of a discrete timed automaton can be accepted by a nondeterministic reversalbounded multicounter machine. Thus, the binary reachability is Presburger. By using the known fact that the emptiness problem is decidable for reversalbounded ...
Predicate abstraction for reachability analysis of hybrid systems
 ACM Trans. Embedded Comput. Syst
, 2006
"... Embedded systems are increasingly finding their way into a growing range of physical devices. These embedded systems often consist of a collection of software threads interacting concurrently with each other and with a physical, continuous environment. While continuous dynamics have been well studie ..."
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Cited by 41 (3 self)
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Embedded systems are increasingly finding their way into a growing range of physical devices. These embedded systems often consist of a collection of software threads interacting concurrently with each other and with a physical, continuous environment. While continuous dynamics have been well studied in control theory, and discrete and distributed systems have been investigated in computer science, the combination of the two complexities leads us to the recent research on hybrid systems. This paper addresses the formal analysis of such hybrid systems. Predicate abstraction has emerged to be a powerful technique for extracting finitestate models from infinitestate discrete programs. This paper presents algorithms and tools for reachability analysis of hybrid systems by combining the notion of predicate abstraction with recent techniques for approximating the set of reachable states of linear systems using polyhedra. Given a hybrid system and a set of predicates, we consider the finite discrete quotient whose states correspond to all possible truth assignments to the input predicates. The tool performs an onthefly exploration of the abstract system. We present the basic techniques for guided search in the abstract statespace, optimizations of these techniques, implementation of these in our verifier, and case studies demonstrating the promise of the approach. We also address the completeness of our abstractionbased verification strategy by showing that predicate abstraction of hybrid systems can be used to prove bounded safety.
Automated test generation from timed automata
 STTT
"... Abstract. Testing is the most dominating validation activity used by industry today, and there is an urgent need for improving its effectiveness, both with respect to the time and resources for test generation and execution, and obtained test coverage. We present a new technique for automatic genera ..."
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Cited by 34 (5 self)
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Abstract. Testing is the most dominating validation activity used by industry today, and there is an urgent need for improving its effectiveness, both with respect to the time and resources for test generation and execution, and obtained test coverage. We present a new technique for automatic generation of realtime blackbox conformance tests for nondeterministic systems from a determinizable class of timed automata specifications with a dense time interpretation. In contrast to other attempts, our tests are generated using a coarse equivalence class partitioning of the specification. To analyze the specification, to synthesize the timed tests, and to guarantee coverage with respect to a coverage criterion, we use the efficient symbolic techniques recently developed for model checking of realtime systems. Application of our prototype tool to a realistic specification shows promising results in terms of both the test suite size, and the time and space used for test generation. 1
Constraint Logic Programming Applied to Model Checking
 IN PROC. 9TH INT. WORKSHOP ON LOGICBASED PROGRAM SYNTHESIS AND TRANSFORMATION (LOPSTR'99), LNCS 1817
, 1999
"... We review and discuss here some of the existing approaches based on CLP (Constraint Logic Programming) for verifying properties of various kinds of statetransition systems. ..."
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Cited by 30 (0 self)
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We review and discuss here some of the existing approaches based on CLP (Constraint Logic Programming) for verifying properties of various kinds of statetransition systems.