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Reflections on Standard ML
 FUNCTIONAL PROGRAMMING, CONCURRENCY, SIMULATION AND AUTOMATED REASONING, VOLUME 693 OF LNCS
, 1992
"... Standard ML is one of a number of new programming languages developed in the 1980s that are seen as suitable vehicles for serious systems and applications programming. It offers an excellent ratio of expressiveness to language complexity, and provides competitive efficiency. Because of its type an ..."
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Cited by 198 (4 self)
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Standard ML is one of a number of new programming languages developed in the 1980s that are seen as suitable vehicles for serious systems and applications programming. It offers an excellent ratio of expressiveness to language complexity, and provides competitive efficiency. Because of its type and module system, Standard ML manages to combine safety, security, and robustness with much of the flexibility of dynamically typed languages like Lisp. It is also has the most welldeveloped scientific foundation of any major language. Here I review the strengths and weaknesses of Standard ML and describe some of what we have learned through the design, implementation, and use of the language.
Regular Types for Active Objects
, 1993
"... Previous work on typetheoretic foundations for objectoriented programming languages has mostly focused on applying or extending functional type theory to functional "objects." This approach, while benefiting from a vast body of existing literature, has the disadvantage of dealing with state change ..."
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Cited by 187 (5 self)
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Previous work on typetheoretic foundations for objectoriented programming languages has mostly focused on applying or extending functional type theory to functional "objects." This approach, while benefiting from a vast body of existing literature, has the disadvantage of dealing with state change either in a roundabout way or not at all, and completely sidestepping issues of concurrency. In particular, dynamic issues of nonuniform service availability and conformance to protocols are not addressed by functional types. We propose a new type framework that characterizes objects as regular (finite state) processes that provide guarantees of service along public channels. We also propose a new notion of subtyping for active objects, based on Brinksma's notion of extension, that extends Wegner and Zdonik's "principle of substitutability" to nonuniform service availability. Finally, we formalize what it means to "satisfy a client's expectations," and we show how regular types canbe used...
Efficient Model Checking Using Tabled Resolution
 Computer Aided Verification (CAV '97)
, 1997
"... We demonstrate the feasibility of using the XSB tabled logic programming system as a programmable fixedpoint engine for implementing efficient local model checkers. In particular, we present XMC, an XSBbased local model checker for a CCSlike valuepassing language and the alternationfree fragmen ..."
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Cited by 118 (32 self)
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We demonstrate the feasibility of using the XSB tabled logic programming system as a programmable fixedpoint engine for implementing efficient local model checkers. In particular, we present XMC, an XSBbased local model checker for a CCSlike valuepassing language and the alternationfree fragment of the modal mucalculus. XMC is written in under 200 lines of XSB code, which constitute a declarative specification of CCS and the modal mucalculus at the level of semantic equations. In order to gauge the performance of XMC as an algorithmic model checker, we conducted a series of benchmarking experiments designed to compare the performance of XMC with the local model checkers implemented in C/C++ in the Concurrency Factory and SPIN specification and verification environments. After applying certain newly developed logicprogrammingbased optimizations (along with some standard ones), XMC's performance became extremely competitive with that of the Factory and shows promise in its comparison with SPIN.
A LinearTime ModelChecking Algorithm for the AlternationFree Modal MuCalculus
 Formal Methods in System Design
, 1993
"... We develop a modelchecking algorithm for a logic that permits propositions to be defined using greatest and least fixed points of mutually recursive systems of equations. This logic is as expressive as the alternationfree fragment of the modal mucalculus identified by Emerson and Lei, and it may ..."
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Cited by 109 (15 self)
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We develop a modelchecking algorithm for a logic that permits propositions to be defined using greatest and least fixed points of mutually recursive systems of equations. This logic is as expressive as the alternationfree fragment of the modal mucalculus identified by Emerson and Lei, and it may therefore be used to encode a number of temporal logics and behavioral preorders. Our algorithm determines whether a process satisfies a formula in time proportional to the product of the sizes of the process and the formula; this improves on the best known algorithm for similar fixedpoint logics. 1 Introduction Behavioral equivalences and preorders, and temporal logics, have been used extensively in automated verification tools for finitestate processes [3, 12, 18, 19, 20]. The relations are typically used to relate a highlevel specification process to a more detailed implementation process, while the logics enable system designers to formulate collections of properties that implementa...
TableauBased Model Checking in the Propositional MuCalculus
 Acta Informatica
, 1990
"... This paper describes a procedure, based around the construction of tableau proofs, for determining whether finitestate systems enjoy properties formulated in the propositional mucalculus. It presents a tableaubased proof system for the logic and proves it sound and complete, and it discusses tech ..."
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Cited by 91 (7 self)
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This paper describes a procedure, based around the construction of tableau proofs, for determining whether finitestate systems enjoy properties formulated in the propositional mucalculus. It presents a tableaubased proof system for the logic and proves it sound and complete, and it discusses techniques for the efficient construction of proofs that states enjoy properties expressed in the logic. The approach is the basis of an ongoing implementation of a model checker in the Concurrency Workbench, an automated tool for the analysis of concurrent systems. 1 Introduction One area of program verification that has proven amenable to automation involves the analysis of finitestate processes. While computer systems in general are not finitestate, many interesting ones, including a variety of communication protocols and hardware systems, are, and their finitary nature enables the development and implementation of decision procedures that test for various properties. Model checking has p...
Model Checking for ContextFree Processes
, 1992
"... We develop a modelchecking algorithm that decides for a given contextfree process whether it satisfies a property written in the alternationfree modal mucalculus. The central idea behind this algorithm is to raise the standard iterative modelchecking techniques to higher order: in contrast to t ..."
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Cited by 78 (8 self)
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We develop a modelchecking algorithm that decides for a given contextfree process whether it satisfies a property written in the alternationfree modal mucalculus. The central idea behind this algorithm is to raise the standard iterative modelchecking techniques to higher order: in contrast to the usual approaches, in which the set of formulas that are satisfied by a certain state are iteratively computed, our algorithm iteratively computes a property transformer for each state class of the finite process representation. These property transformers can then simply be applied to solve the modelchecking problem. The complexity of our algorithm is linear in the size of the system's representation and exponential in the size of the property being investigated.
Modal and Temporal Logics for Processes
, 1996
"... this paper have been presented at the 4th European Summer School in Logic, Language and Information, University of Essex, 1992; at the Tempus Summer School for Algebraic and Categorical Methods in Computer Science, Masaryk University, Brno, 1993; and the Summer School in Logic Methods in Concurrency ..."
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Cited by 69 (2 self)
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this paper have been presented at the 4th European Summer School in Logic, Language and Information, University of Essex, 1992; at the Tempus Summer School for Algebraic and Categorical Methods in Computer Science, Masaryk University, Brno, 1993; and the Summer School in Logic Methods in Concurrency, Aarhus University, 1993. I would like to thank the organisers and the participants of these summer schools, and of the Banff higher order workshop. I would also like to thank Julian Bradfield for use of his Tex tree constructor for building derivation trees and Carron Kirkwood, Faron Moller, Perdita Stevens and David Walker for comments on earlier drafts.
Transformational Design and Implementation Of A New Efficient Solution To The Ready Simulation Problem
 Science of Computer Programming
, 1995
"... A transformational methodology is described for simultaneously designing algorithms and developing programs. The methodology makes use of three transformational tools  dominated convergence, finite differencing, and realtime simulation of a set machine on a RAM. We illustrate the methodology t ..."
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Cited by 42 (2 self)
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A transformational methodology is described for simultaneously designing algorithms and developing programs. The methodology makes use of three transformational tools  dominated convergence, finite differencing, and realtime simulation of a set machine on a RAM. We illustrate the methodology to design a new O(mn + n 2 )time algorithm for deciding when nstate, mtransition processes are ready similar, which is a substantial improvement on the \Theta(mn 6 ) algorithm presented in [6]. The methodology is also used to derive a program whose performance, we believe, is competitive with the most efficient handcrafted implementation of our algorithm. Ready simulation is the finest fully abstract notion of process equivalence in the CCS setting. 1 Introduction Currently there is a wide gap between the goals and practices of research in the theory of algorithm design and the science of programming, which we believe is A preliminary version of this paper appeared in the Conf...
Using Integer Programming to Verify General Safety and Liveness Properties
 Formal Methods in System Design
, 1993
"... . Analysis of concurrent systems is plagued by the state explosion problem. The constrained expression analysis technique uses necessary conditions, in the form of linear inequalities, to verify certain properties of concurrent systems, thus avoiding the enumeration of the potentially explosive num ..."
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Cited by 40 (17 self)
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. Analysis of concurrent systems is plagued by the state explosion problem. The constrained expression analysis technique uses necessary conditions, in the form of linear inequalities, to verify certain properties of concurrent systems, thus avoiding the enumeration of the potentially explosive number of reachable states of the system. This technique has been shown to be capable of verifying simple safety properties, like freedom from deadlock, that can be expressed in terms of the number of certain events occurring in a finite execution, and has been successfully used to analyze a variety of concurrent software systems. We extend this technique to the verification of more complex safety properties that involve the order of events and to the verification of liveness properties, which involve infinite executions. 1 Introduction Many concurrent systems can be modeled as a set of communicating finite state machines. In theory, this allows properties of such systems to be verified automa...
Time Abstracted Bisimulation: Implicit Specifications and Decidability
, 1997
"... ed Bisimulation: Implicit Specifications and Decidability Kim G. Larsen y and Yi Wang z January 8, 1997 Abstract In the last few years a number of realtime process calculi have emerged with the purpose of capturing important quantitative aspects of realtime systems. In addition, a number o ..."
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Cited by 39 (9 self)
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ed Bisimulation: Implicit Specifications and Decidability Kim G. Larsen y and Yi Wang z January 8, 1997 Abstract In the last few years a number of realtime process calculi have emerged with the purpose of capturing important quantitative aspects of realtime systems. In addition, a number of process equivalences sensitive to timequantities have been proposed, among these the notion of timed (bisimulation) equivalence in In this paper, we introduce a timeabstracting (bisimulation) equivalence, and investigate its properties with respect to the realtime process calculus of [Wan90]. Seemingly, such an equivalence would yield very little information (if any) about the timing properties of a process. However, timeabstracted reasoning about a composite process may yield important information about the relative timingproperties of the components of the system. In fact, we show as a main theorem that such implicit reasoning will reveal all timing aspects of a process. More p...