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Sequential abstract state machines capture sequential algorithms
 ACM Trans. Computational logic
"... We examine sequential algorithms and formulate a Sequential Time Postulate, an Abstract State Postulate, and a Bounded Exploration Postulate. Analysis of the postulates leads us to the notion of sequential abstract state machine and to the theorem in the title. First we treat sequential algorithms t ..."
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Cited by 131 (28 self)
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We examine sequential algorithms and formulate a Sequential Time Postulate, an Abstract State Postulate, and a Bounded Exploration Postulate. Analysis of the postulates leads us to the notion of sequential abstract state machine and to the theorem in the title. First we treat sequential algorithms that are deterministic and noninteractive. Then we consider sequential algorithms that may be nondeterministic and that may interact with their environments.
Semantic Essence of AsmL
, 2004
"... The Abstract State Machine Language, AsmL, is a novel executable specification language based on the theory of Abstract State Machines. AsmL is objectoriented, provides highlevel mathematical datastructures, and is built around the notion of synchronous updates and finite choice. AsmL is full ..."
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Cited by 50 (6 self)
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The Abstract State Machine Language, AsmL, is a novel executable specification language based on the theory of Abstract State Machines. AsmL is objectoriented, provides highlevel mathematical datastructures, and is built around the notion of synchronous updates and finite choice. AsmL is fully integrated into the .NET framework and Microsoft development tools. In this paper, we explain the design rationale of AsmL and provide static and dynamic semantics for a kernel of the language.
Spying on Components: A Runtime Verification Technique
, 2001
"... A natural way to specify componentbased systems is by an interface specification. Such a specification allows clients of a component to know not only its syntactic properties, as is current practice, but also its semantic properties. Any component implementation must be a behavioral refinement of i ..."
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Cited by 34 (2 self)
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A natural way to specify componentbased systems is by an interface specification. Such a specification allows clients of a component to know not only its syntactic properties, as is current practice, but also its semantic properties. Any component implementation must be a behavioral refinement of its interface specification. We propose the use of executable specifications and a runtime monitor to check for behavioral equivalence between a component and its specification. Furthermore, we take advantage of the COM infrastructure to perform this kind of runtime verification without any instrumentation of the implementation, i.e., without any recompilation or relinking.
The Semantics of the Java Programming Language: Preliminary Version
, 1997
"... A mathematical model of the Java programming language is constructed. ..."
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Cited by 13 (0 self)
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A mathematical model of the Java programming language is constructed.
Formal Foundations of Computer Security
 Science for Peace and Security Series D: Information and Communication Security, Vol
, 2008
"... We would like to know with very high confidence that private data in computers is not unintentionally disclosed and that only authorized persons or processes can modify it. Proving security properties of software systems has always been hard because we are trying to show that something bad cannot ha ..."
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Cited by 13 (8 self)
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We would like to know with very high confidence that private data in computers is not unintentionally disclosed and that only authorized persons or processes can modify it. Proving security properties of software systems has always been hard because we are trying to show that something bad cannot happen no matter what a hostile adversary tries
Choiceless polynomial time, counting and the Cai–Fürer–Immerman graphs (Extended Abstract)
 IN: PROC. 12TH WORKSHOP ON LOGIC, LANGUAGE, INFORMATION AND COMPUTATION
, 2007
"... We consider Choiceless Polynomial Time ( ˜ CPT), a language introduced by Blass, Gurevich and Shelah, and show that it can express a query originally constructed by Cai, Fürer and Immerman to separate fixedpoint logic with counting (IFP + C) from P. This settles a question posed by Blass et al. Th ..."
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Cited by 11 (4 self)
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We consider Choiceless Polynomial Time ( ˜ CPT), a language introduced by Blass, Gurevich and Shelah, and show that it can express a query originally constructed by Cai, Fürer and Immerman to separate fixedpoint logic with counting (IFP + C) from P. This settles a question posed by Blass et al. The program we present uses sets of unbounded finite rank: we demonstrate that this is necessary by showing that the query cannot be computed by any program that has a constant bound on the rank of sets used, even in ˜ CPT(Card), an extension of ˜ CPT with counting.
The ASM Workbench: an Open and Extensible Tool Environment for Abstract State Machines
, 1998
"... State Machines Giuseppe Del Castillo giusp@unipaderborn.de Heinz Nixdorf Institut, UniversitatGH Paderborn Furstenallee 11, 33102 Paderborn, Germany Abstract. Appropriate tool support is an essential factor for an effective application of formal methods to reallife specification and modelling ..."
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Cited by 8 (0 self)
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State Machines Giuseppe Del Castillo giusp@unipaderborn.de Heinz Nixdorf Institut, UniversitatGH Paderborn Furstenallee 11, 33102 Paderborn, Germany Abstract. Appropriate tool support is an essential factor for an effective application of formal methods to reallife specification and modelling tasks. However, the current state of the art of tool support for Abstract State Machines is not considered very satisfactory by practitioners. After discussing some possible reasons for this, we report about the ASM Workbench, an open and extensible tool environment developed in response to this situation. 1 Introduction and Motivation There is a wide agreement on the fact that some degree of tool support is necessary in order to gain practical advantages from the application of formal methods to concrete specification and modelling tasks. In fact, the spectrum of available tools supporting formal methods is at least as varied as the spectrum of formal methods themselves, including for inst...
PTIME Queries Revisited
, 2005
"... The existence of a language expressing precisely the PTIME queries on arbitrary structures remains the central open problem in the theory of database query languages. As it turns out, two variants of this question have been formulated. Surprisingly, despite the importance of the problem, the relatio ..."
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The existence of a language expressing precisely the PTIME queries on arbitrary structures remains the central open problem in the theory of database query languages. As it turns out, two variants of this question have been formulated. Surprisingly, despite the importance of the problem, the relationship between these variants has not been systematically explored. A first contribution of the present paper is to revisit the basic definitions and clarify the connection between these two variants. We then investigate two relaxations to the original problem that appear as tempting alternatives in the absence of a language for the PTIME queries. The first consists in trying to express the PTIME queries using a richer language that can also express queries beyond PTIME, but for which there exists a query processor evaluating all PTIME queries in PTIME. The second approach, studied by many researchers, is to focus on PTIME properties on restricted sets of graphs. Our results are mostly negative, and point out limitations to both approaches. Finally, we turn to a natural class of languages that we call finitely generated, whose syntax is obtained by applying a fixed set of constructors to a given set of building blocks. We identify a broad class of such languages that cannot express all the PTIME queries.
FixedPoint Definability and Polynomial Time
"... Abstract. My talk will be a survey of recent results about the quest for a logic capturing polynomial time. In a fundamental study of database query languages, Chandra and Harel [4] first raised the question of whether there exists a logic that captures polynomial time. Actually, Chandra and Harel p ..."
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Abstract. My talk will be a survey of recent results about the quest for a logic capturing polynomial time. In a fundamental study of database query languages, Chandra and Harel [4] first raised the question of whether there exists a logic that captures polynomial time. Actually, Chandra and Harel phrased the question in a somewhat disguised form; the version that we use today goes back to Gurevich [15]. Briefly, but slightly imprecisely, 1 a logic L captures a complexity class K if exactly those properties of finite structures that are decidable in K are definable in L. The existence of a logic capturing PTIME is still wide open, and it is viewed as one of the main open problems in finite model theory and database theory. One reason the question is interesting is that we know from Fagin’s Theorem [9] that existential secondorder logic captures NP, and we also know that there are logics capturing most natural complexity classes above NP. Gurevich conjectured that there is no logic capturing PTIME. If this conjecture was true, this would not only imply that PTIME ̸ = NP, but it would also show that NP and the complexity
A logic for PTIME and a parameterized halting problem
 ELECTRONIC COLLOQUIUM ON COMPUTATIONAL COMPLEXITY, REPORT NO. 83
, 2008
"... In [2] a logic LY has been introduced as a possible candidate for a logic capturing the PTIME properties of structures (even in the absence of an ordering of their universe). A reformulation of this problem in terms of a parameterized halting problem pACC for nondeterministic Turing machines has be ..."
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Cited by 4 (2 self)
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In [2] a logic LY has been introduced as a possible candidate for a logic capturing the PTIME properties of structures (even in the absence of an ordering of their universe). A reformulation of this problem in terms of a parameterized halting problem pACC for nondeterministic Turing machines has been given in [10]. We analyze the precise relationship between LY and pACC. Moreover, we show that pACC is not fixedparameter tractable if âP != NP holds for all time constructible functions.â This property also implies that the natural parameterization of GÃödel's proof predicate is not fixedparameter tractable. Furthermore, the complexity of various variants of pACC is considered.