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26
Completing the Temporal Picture
, 1991
"... The paper presents a relatively complete proof system for proving the validity of temporal properties of reactive programs. The presented proof system improves on previous temporal systems, in that it reduces the validity of program properties into pure assertional reasoning, not involving additiona ..."
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Cited by 74 (16 self)
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The paper presents a relatively complete proof system for proving the validity of temporal properties of reactive programs. The presented proof system improves on previous temporal systems, in that it reduces the validity of program properties into pure assertional reasoning, not involving additional temporal reasoning. The proof system is based on the classification of temporal properties according to the Borel hierarchy, providing appropriate proof rules for the classes of safety, response, and reactivity properties.
An Implementation of Three Algorithms for Timing Verification Based on Automata Emptiness
, 1992
"... This papers describes modifications to and the implementation of algorithms previously described in [1, 11]. We first describe three generic (untimed) algorithms for constructing graphs of the reachable states of a system, and how these graphs can be used for verification. They all have as input an ..."
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Cited by 59 (3 self)
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This papers describes modifications to and the implementation of algorithms previously described in [1, 11]. We first describe three generic (untimed) algorithms for constructing graphs of the reachable states of a system, and how these graphs can be used for verification. They all have as input an implicit description of a transition system. We then apply these algorithms to realtime systems. The first algorithm performs a straightforward reachability analysis on sets of states of the system, rather than on individual states. This corresponds to stepping symbolically through the system many states at a time. In the case of a realtime system this procedure constructs a graph where each node is the union of some regions of the regions graph. There is therefore no need for an a priori partitioning of the state space into individual regions; however, this approach potentially leads to exponentially worse complexity since its potential state space is the power set of regions [1]. The other two algorithms we consider are minimization algorithms [12, 13, 11]. These simultaneously perform reachability analysis and minimization from an implicit system description. These can lead to great savings when the minimized graph is much smaller than the explicit reachable graph. Our paradigm for verification is to test for the emptiness of the set of all timed system executions that violate a requirements specification. One way to specify and verify nonterminating processes is to model them as languages of !sequences of events [14, 15, 16, 1, 17, 18]. Modular processes can be constructed via composition operations involving language intersection. Specifications are also given as languages: they contain all acceptable event sequences. Program correctness is then just language contain...
The Anchored Version of the Temporal Framework
 Linear Time, Branching Time, and Partial Order in Logics and Models for Concurrency, Lecture Notes in Computer Science 354
, 1989
"... . In this survey paper we present some of the recent developments in the temporal formal system for the specification, verification and development of reactive programs. While the general methodology remains very much the one presented in some earlier works on the subject, such as [MP83c, MP83a, Pnu ..."
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Cited by 50 (5 self)
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. In this survey paper we present some of the recent developments in the temporal formal system for the specification, verification and development of reactive programs. While the general methodology remains very much the one presented in some earlier works on the subject, such as [MP83c, MP83a, Pnu86], there have been several technical improvements and gained insights in understanding the computational model, the logic itself, the proof system and its presentation, and connections with alternative formalisms, such as finite automata. In this paper we explicate some of these improvements and extensions. The main difference between this and preceding versions is that here we consider a notion of validity for temporal formulae, which is anchored at the initial state of the computation. The paper discusses some of the consequences of this decision. Key words: Temporal Logic, Reactive Systems, Concurrent Programs, Specification, Verification, Proof System, Classification of Prtoperties, Sa...
Verification of Concurrent Programs: The AutomataTheoretic Framework
 Annals of Pure and Applied Logic
, 1987
"... We present an automatatheoretic framework to the verification of concurrent and nondeterministic programs. The basic idea is that to verify that a program P is correct one writes a program A that receives the computation of P as input and diverges only on incorrect computations of P . Now P is c ..."
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Cited by 47 (3 self)
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We present an automatatheoretic framework to the verification of concurrent and nondeterministic programs. The basic idea is that to verify that a program P is correct one writes a program A that receives the computation of P as input and diverges only on incorrect computations of P . Now P is correct if and only if a program PA , obtained by combining P and A, terminates. We formalize this idea in a framework of !automata with a recursive set of states. This unifies previous works on verification of fair termination and verification of temporal properties. 1 Introduction In this paper we present an automatatheoretic framework that unifies several trends in the area of concurrent program verification. The trends are temporal logic, model checking, automata theory, and fair termination. Let us start with a survey of these trends. In 1977 Pnueli suggested the use of temporal logic in the verification of concurrent programs [Pn77]. The basic motivation is that in the verificat...
Certifying Model Checkers
 In 13th International Conference Computer Aided Verification
, 2001
"... Model Checking is an algorithmic technique to determine whether a temporal property holds of a program. For linear time properties, a model checker produces a counterexample computation if the check fails. This computation acts as a "certificate" of failure, as it can be checked easily and indep ..."
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Cited by 34 (1 self)
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Model Checking is an algorithmic technique to determine whether a temporal property holds of a program. For linear time properties, a model checker produces a counterexample computation if the check fails. This computation acts as a "certificate" of failure, as it can be checked easily and independently of the model checker by simulating it on the program. On the other hand, no such certificate is produced if the check succeeds. In this paper, we show how this asymmetry can be eliminated with a certifying model checker. The key idea is that, with some extra bookkeeping, a model checker can produce a deductive proof on either success or failure. This proof acts as a certificate of the result, as it can be checked mechanically by simple, nonfixpoint methods that are independent of the model checker. We develop a deductive proof system for verifying branching time properties expressed in the mucalculus, and show how to generate a proof in this system from a model checking run. Proofs for linear time properties form a special case. A model checker that generates proofs can be used for many interesting applications, such as better ways of exploring errors in a program, and a tight integration of model checking with automated theorem proving. 1
Formal Methods for the Specification and Design of RealTime Safety Critical Systems
, 1992
"... Safety critical computers increasingly a#ect nearly every aspect of our lives. Computers control the planes we #y on, monitor our health in hospitals and do our work in hazardous environments. Computers with software de#ciencies that fail to meet stringent timing constraints have resulted in cat ..."
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Cited by 31 (0 self)
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Safety critical computers increasingly a#ect nearly every aspect of our lives. Computers control the planes we #y on, monitor our health in hospitals and do our work in hazardous environments. Computers with software de#ciencies that fail to meet stringent timing constraints have resulted in catastrophic failures. This paper surveys formal methods for specifying, designing and verifying realtime systems, so as to improve their safety and reliability. # To appear in Journal of Systems and Software,Vol. 18, Number 1, pages 33#60, April 1992. Jonathan Ostro# is with the Department of Computer Science, York University 4700 Keele Street, North York, Ontario, Canada, M3J 1P3. This work is supported by the Natural Sciences and Engineering Research Council of Canada. 1 CONTENTS 2 Contents 1 Introduction 3 2 De#ning the terms 6 2.1 Major issues that formal theories must address ::::::: 13 3 RealTime Programming Languages 14 4 Structured Methods and#or Graphical Languages 15 4.1 Str...
A Temporal Proof Methodology for Reactive Systems
, 1993
"... The paper presents a minimal proof theory which is adequate for proving the main important temporal properties of reactive programs. The properties we consider consist of the classes of invariance and response properties. For each of these classes we present a small set of rules that is complete for ..."
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Cited by 16 (0 self)
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The paper presents a minimal proof theory which is adequate for proving the main important temporal properties of reactive programs. The properties we consider consist of the classes of invariance and response properties. For each of these classes we present a small set of rules that is complete for verifying properties belonging to this class. We illustrate the application of these rules on several examples. We discuss concise presentations of complex proofs using the devices of transition tables and proof diagrams.
From Complementation to Certification
, 2004
"... In the automatatheoretic approach to model checking we check the emptiness of the product of a system S with an automaton A: for the complemented specification. This gives rise to two automatatheoretic problems: complementation of word automata, which is used in order to generate A: , and the ..."
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Cited by 14 (3 self)
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In the automatatheoretic approach to model checking we check the emptiness of the product of a system S with an automaton A: for the complemented specification. This gives rise to two automatatheoretic problems: complementation of word automata, which is used in order to generate A: , and the emptiness problem, to which model checking is reduced. Both problems have numerous other applications, and have been extensively studied for nondeterministic Buchi word automata (NBW). Nondeterministic generalized Buchi word automata (NGBW) have become popular in specification and verification and are now used in applications traditionally assigned to NBW. This is due to their richer acceptance condition, which leads to automata with fewer states and a simpler underlying structure.
Synthesis of Hybrid ConstraintBased Controllers
 HYBRID SYSTEMS II, LECTURE NOTES IN COMPUTER SCIENCE 999
, 1995
"... A robot is an integrated system, with a controller embedded in its plant. We take a robotic system to be the coupling of a robot to its environment. Robotic ..."
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Cited by 14 (9 self)
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A robot is an integrated system, with a controller embedded in its plant. We take a robotic system to be the coupling of a robot to its environment. Robotic