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ConGolog, a concurrent programming language based on the situation calculus: language and implementation
, 1998
"... As an alternative to planning, an approach to highlevel agent control based on concurrent program execution is considered. The language includes facilities for prioritizing the concurrent execution, interrupting the execution when certain conditions become true, and dealing with exogenous actions. ..."
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Cited by 206 (37 self)
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As an alternative to planning, an approach to highlevel agent control based on concurrent program execution is considered. The language includes facilities for prioritizing the concurrent execution, interrupting the execution when certain conditions become true, and dealing with exogenous actions. The language di ers from other procedural formalisms for concurrency in that the initial state can be incompletely speci ed and the primitive actions can be userde ned by axioms in the situation calculus. In a companion paper, a formal de nition in the situation calculus of such a programming language is presented and illustrated with detailed examples. In this paper, the mathematical properties of the programming language are explored. 1
Modeling Languages: Syntax, Semantics and All That Stuff Part I: The Basic Stuff
, 2000
"... The motivation for this paper, the first in a planned series of three parts, is the multitude of concepts surrounding the proper definition of complex modeling languages for systems and software, and the confusion that this often causes. ..."
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Cited by 61 (1 self)
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The motivation for this paper, the first in a planned series of three parts, is the multitude of concepts surrounding the proper definition of complex modeling languages for systems and software, and the confusion that this often causes.
Verification of Temporal Properties of Processes in a Setting with Data
 In A.M. Haeberer, editor, AMAST’98, volume 1548 of LNCS
, 1999
"... . We define a valuebased modal calculus, built from firstorder formulas, modalities, and fixed point operators parameterized by data variables, which allows to express temporal properties involving data. We interpret this logic over Crl terms defined by linear process equations. The satisfacti ..."
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Cited by 22 (8 self)
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. We define a valuebased modal calculus, built from firstorder formulas, modalities, and fixed point operators parameterized by data variables, which allows to express temporal properties involving data. We interpret this logic over Crl terms defined by linear process equations. The satisfaction of a temporal formula by a Crl term is translated to the satisfaction of a firstorder formula containing parameterized fixed point operators. We provide proof rules for these fixed point operators and show their applicability on various examples. 1 Introduction In recent years we have applied process algebra in numerous settings [4, 8, 12]. The first lesson we learned is that process algebra pur sang is not very handy, and we need an extension with data. This led to the language Crl (micro Common Representation Language) [13]. The next observation was that it is very convenient to eliminate the parallel operator from a process description and reduce it to a very restricted form, whi...
Machine code programs are predicates too
 Sixth Refinement Workshop
, 1994
"... I present aninterpretation of machine language programs as boolean expressions. Source language programs may also be so interpreted. The correctness of a code generator can then be expressed as a simple relationship between boolean expressions. Code generators can then be calculated from their speci ..."
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Cited by 12 (2 self)
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I present aninterpretation of machine language programs as boolean expressions. Source language programs may also be so interpreted. The correctness of a code generator can then be expressed as a simple relationship between boolean expressions. Code generators can then be calculated from their speci cation. 1
A fixpoint theory for nonmonotonic parallelism
, 2002
"... This paper studies parallel recursion. The trace specification language used in this paper incorporates sequential,j nondeterminism, reactiveness(inclvenessg,F'k traces), three forms of paral'VgJj (inclVgJjqMkEglglgl fairinterlkEglgl synchronous paralonousg and general recursion. In order to use Ta ..."
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Cited by 8 (5 self)
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This paper studies parallel recursion. The trace specification language used in this paper incorporates sequential,j nondeterminism, reactiveness(inclvenessg,F'k traces), three forms of paral'VgJj (inclVgJjqMkEglglgl fairinterlkEglgl synchronous paralonousg and general recursion. In order to use Tarski's theorem to determine the fixpoints of recursions, we need to identify awelVjgJ,FIq partial order.Several orders are considered,incldered new order calrg the lexical order, which tends tosimulM, the execution of a recursion in asimilk manner as the EglVqgJ,E, order. A theorem of this paper shows that no appropriate order exists for the lhegIIIE Tarski's theoremalor is not enough to determine the fixpoints ofparalVI recursions. Instead of usingTarski's theoremdirectl, we reason about the fixpoints of terminatingand nonterminatingbehavioursseparateli Such reasoningis supported by the leg of a new compositioncalio partition. We propose a fixpoint techniquecalni the partitioned fixpoint, which is thelgqk fixpoint of the nonterminatingbehaviours after the terminatingbehaviours reach their greatest fixpoint. The surprisingresul is thataltg,M, a recursion may not beljV"EgJqVE' monotonic, it must have the partitioned fixpoint, which isequal to thelegj lgjIjI,gJqF' fixpoint. Since the partitioned #xpoint iswel defined in anycompl,q lmpl,q theresulq areappljFMgJ to various semanticmodeli Existing fixpoint techniques simpl becomespecial cases of the partitioned fixpoint. Forexamplj an EglIIqgJq',EFglEFg recursion has itslsgj EglMMFIgJq fixpoint, which can be shown to be the same as the partitioned fixpoint. The new technique is moregeneral than thelegq EglEEkIgJq fixpoint in that the partitioned fixpoint can be determined even when a recursion is notEglVjjVgJq monotonic.Exampln of nonmonotonic recur...
Nonmonotone Fixpoint Iterations to Resolve Second Order Effects
, 1996
"... We present a new fixpoint theorem which guarantees the existence and the finite computability of the least common solution of a countable system of recursive equations over a wellfounded domain. The functions are only required to be increasing and delaymonotone, the latter being a property much ..."
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Cited by 6 (2 self)
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We present a new fixpoint theorem which guarantees the existence and the finite computability of the least common solution of a countable system of recursive equations over a wellfounded domain. The functions are only required to be increasing and delaymonotone, the latter being a property much weaker than monotonicity. We hold that wellfoundedness is a natural condition as it guarantees termination of every fixpoint computation algorithm. Our fixpoint theorem covers, under the wellfoundedness condition, all the known `synchronous' versions of fixpoint theorems. To demonstrate its power and versatility we contrast an application in data flow analysis, where known versions are applicable as well, to a practically relevant application in program optimization, which due to its second order effects, requires the full strength of our new theorem. In fact, the new theorem is central for establishing the optimality of the partial dead code elimination algorithm considered, which is implemented in the new release of the Sun SPARCompiler language systems.
Chaotic Fixed Point Iterations
, 1994
"... In this paper we present a new fixed point theorem applicable for a countable system of recursive equations over a wellfounded domain. Wellfoundedness is an essential feature of many computer science applications as it guarantees termination of the corresponding fixed point computation algorithms. B ..."
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Cited by 6 (3 self)
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In this paper we present a new fixed point theorem applicable for a countable system of recursive equations over a wellfounded domain. Wellfoundedness is an essential feature of many computer science applications as it guarantees termination of the corresponding fixed point computation algorithms. Besides being a natural restriction, it marks a new area of application, where not even monotonicity is required. We demonstrate the power and versatility of our fixed point theorem, which under the wellfoundedness condition covers all the known `synchronous' versions of fixed point theorems, by means of applications in data flow analysis and program optimization. Keywords Fixed point, chaotic iteration, vector iteration, data flow analysis, program optimization, workset algorithm, partial dead code elimination. Contents 1 Introduction 1 2 Theory 2 2.1 The Main Theorem : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 2 2.2 Vector Iterations : : : : : : : : : : : : : : : : : :...
Predicative Semantics of Loops
, 1997
"... A predicative semantics is a mapping of programs to predicates. These predicates characterize sets of acceptable observations. The presence of time in the observations makes the obvious weakest fixedpoint semantics of iterative constructs unacceptable. This paper proposes an alternative. We will se ..."
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Cited by 3 (1 self)
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A predicative semantics is a mapping of programs to predicates. These predicates characterize sets of acceptable observations. The presence of time in the observations makes the obvious weakest fixedpoint semantics of iterative constructs unacceptable. This paper proposes an alternative. We will see that this alternative semantics is monotone and implementable (feasible). Finally a programming theorem for iterative constructs is proposed, proved, and demonstrated. A novel aspect of this theorem is that it is not based on invariants. Keywords Predicative semantics, fixedpoint semantics, recursion, loops, refinement calculi. 0 FORMALIZATION 0.0 Specifications and refinement Define xnat as the set of all natural numbers (nat) joined with an additional object 1. We will suppose the following properties of 1: it is larger than any natural number; 1 + i = 1 \Gamma i = 1; for all natural numbers i; and 1 \Gamma 1 = 0. I will use a `batch' model for specifications borrowed, in most res...