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Static Inference of Modes and Data Dependencies in Logic Programs
 ACM Transactions on Programming Languages and Systems
, 1989
"... Abstract: Mode and data dependency analyses find many applications in the generation of efficient executable code for logic programs. For example, mode information can be used to generate specialized unification instructions where permissible; to detect determinacy and functionality of programs; to ..."
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Cited by 93 (8 self)
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Abstract: Mode and data dependency analyses find many applications in the generation of efficient executable code for logic programs. For example, mode information can be used to generate specialized unification instructions where permissible; to detect determinacy and functionality of programs; to generate index structures more intelligently; to reduce the amount of runtime tests in systems that support goal suspension; and in the integration of logic and functional languages. Data dependency information can be used for various sourcelevel optimizing transformations, to improve backtracking behavior, and to parallelize logic programs. This paper describes and proves correct an algorithm for the static inference of modes and data dependencies in a program. The algorithm is shown to be quite efficient for programs commonly encountered in practice.
Operational Semantics for Declarative MultiParadigm Languages
 Journal of Symbolic Computation
, 2005
"... Abstract. In this paper we define an operational semantics for functional logic languages covering notions like laziness, sharing, concurrency, nondeterminism, etc. Such a semantics is not only important to provide appropriate language definitions to reason about programs and check the correctness ..."
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Cited by 68 (29 self)
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Abstract. In this paper we define an operational semantics for functional logic languages covering notions like laziness, sharing, concurrency, nondeterminism, etc. Such a semantics is not only important to provide appropriate language definitions to reason about programs and check the correctness of implementations but it is also a basis to develop languagespecific tools, like program tracers, profilers, optimizers, etc. First, we define a &quot;bigstep &quot; semantics in natural style to relate expressions and their evaluated results. Since this semantics is not sufficient to cover concurrency, search strategies, or to reason about costs associated to particular computations, we also define a &quot;smallstep &quot; operational semantics covering the features of modern functional logic languages.
Denotational and operational semantics for prolog
 Journal of Logic Programming
, 1988
"... Abstract: The semantics of Prolog programs is usually given in terms of the model theory of first order logic. However, this does not adequately characterize the computational behavior of Prolog programs. Prolog implementations typically use a sequential evaluation strategy based on the textual orde ..."
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Cited by 58 (4 self)
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Abstract: The semantics of Prolog programs is usually given in terms of the model theory of first order logic. However, this does not adequately characterize the computational behavior of Prolog programs. Prolog implementations typically use a sequential evaluation strategy based on the textual order of clauses and literals in a program, as well as nonlogical features like ‘‘cut’’. In this work we develop a denotational semantics that captures the computational behavior of Prolog. We present a semantics for ‘‘cutfree’ ’ Prolog, which is then extended to Prolog with cut. For each case we develop a congruence proof that relates the semantics to a standard operational interpreter. As an application of our denotational semantics, we show the correctness of some standard ‘‘folk’ ’ theorems regarding transformations on Prolog programs.
A Mathematical Definition of Full Prolog
, 1994
"... The paper provides a mathematical yet simple model for the full programming language Prolog, as apparently intended by the ISO draft standard proposal. The model includes all control constructs, database operations, solution collecting predicates and error handling facilities, typically ignored by p ..."
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Cited by 58 (9 self)
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The paper provides a mathematical yet simple model for the full programming language Prolog, as apparently intended by the ISO draft standard proposal. The model includes all control constructs, database operations, solution collecting predicates and error handling facilities, typically ignored by previous theoretical treatments of the language. We add to this the ubiquitous boxmodel debugger. The model directly reflects the basic intuitions underlying the language and can be used as a primary mathematical definition of Prolog. The core of the model has been applied for mathematical analysis of implementations, for clarification of disputable language features and for specifying extensions of the language in various directions. The model may provide guidance for extending the established theory of logic programming to the extralogical features of Prolog. Introduction One of the original aims of mathematical semantics was to provide the programmer with a set of mathematical models and...
Functional computations in logic programs
 ACM Transactions on Programming Languages and Systems
, 1989
"... Abstract: While the ability to simulate nondeterminism and compute multiple solutions for a single query is a powerful and attractive feature of logic programming languages, it is expensive in both time and space. Since programs in such languages are very often functional, i.e. do not produce more t ..."
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Cited by 53 (11 self)
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Abstract: While the ability to simulate nondeterminism and compute multiple solutions for a single query is a powerful and attractive feature of logic programming languages, it is expensive in both time and space. Since programs in such languages are very often functional, i.e. do not produce more than one distinct solution for a single input, this overhead is especially undesirable. This paper describes how programs may be analyzed statically to determine which literals and predicates are functional, and how the program may then be optimized using this information. Our notion of ‘‘functionality’ ’ subsumes the notion of ‘‘determinacy’ ’ that has been considered by various researchers. Our algorithm is less reliant on language features such as the cut, and thus extends more easily to parallel execution strategies, than others that have been proposed.
Why use evolving algebras for hardware and software engineering?
, 1995
"... In this paper I answer the question how evolving algebras can be used for the design and analysis of complex hardware and software systems. I present the salient features of this new method and illustrate them through several examples from my work on specification and verification of programming lan ..."
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Cited by 39 (4 self)
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In this paper I answer the question how evolving algebras can be used for the design and analysis of complex hardware and software systems. I present the salient features of this new method and illustrate them through several examples from my work on specification and verification of programming languages, compilers, protocols and architectures. The definition of a mathematical model for Hennessy and Patterson's RISC architecture DLX serves as a running example; this model is used in [24] to prove the correctness of instruction pipelining. I will point out the yet unexplored potential of the evolving algebra method for largescale industrial applications.
Continuation Semantics for Prolog with Cut
, 1989
"... We present a denotational continuation semantics for Prolog with cut. First a uniform language B is studied, which captures the control flow aspects of Prolog. The denotational semantics for B is proven equivalent to a transition system based operational semantics. The congruence proof relies on the ..."
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Cited by 39 (5 self)
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We present a denotational continuation semantics for Prolog with cut. First a uniform language B is studied, which captures the control flow aspects of Prolog. The denotational semantics for B is proven equivalent to a transition system based operational semantics. The congruence proof relies on the representation of the operational semantics as a chain of approximations and on a convenient induction principle. Finally, we interpret the abstract language B such that we obtain equivalent denotational and operational models for Prolog itself. Section 1 Introduction In the nice textbook of Lloyd [Ll] the cut, available in all Prologsystems, is described as a controversial control facility. The cut, added to the Horn clause logic for efficiency reasons, affects the completeness of the refutation procedure. Therefore the standard declarative semantics using Herbrand models does not adequately capture the computational aspects of the Prologlanguage. In the present paper we study the Prolog...
Modelling Prolog Control
, 1992
"... The goal of this paper is to construct a semantic basis for the abstract interpretation of Prolog programs. Prolog is a wellknown logic programming language which applies a depthfirst search strategy in order to provide a practical approximation of Horn clause logic. While pure logic programming h ..."
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Cited by 28 (13 self)
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The goal of this paper is to construct a semantic basis for the abstract interpretation of Prolog programs. Prolog is a wellknown logic programming language which applies a depthfirst search strategy in order to provide a practical approximation of Horn clause logic. While pure logic programming has clean fixpoint, modeltheoretic and operational semantics the situation for Prolog is different. Difficulties in capturing the declarative meaning of Prolog programs have led to various semantic definitions which attempt to encode the search strategy in different mathematical frameworks. However semantic based analyses of Prolog are typically achieved by abstracting the more simple but less precise declarative semantics of pure logic Programs. We propose instead to model Prolog control in a simple constraint logic language which is presented together with its declarative and operational semantics. This enables us to maintain the usual approach to declarative semantics of logic programs wh...
Algebra of logic programming
 International Conference on Logic Programming
, 1999
"... At present, the field of declarative programming is split into two main areas based on different formalisms; namely, functional programming, which is based on lambda calculus, and logic programming, which is based on firstorder logic. There are currently several language proposals for integrating th ..."
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Cited by 24 (4 self)
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At present, the field of declarative programming is split into two main areas based on different formalisms; namely, functional programming, which is based on lambda calculus, and logic programming, which is based on firstorder logic. There are currently several language proposals for integrating the expressiveness of these two models of computation. In this thesis we work towards an integration of the methodology from the two research areas. To this end, we propose an algebraic approach to reasoning about logic programs, corresponding to the approach taken in functional programming. In the first half of the thesis we develop and discuss a framework which forms the basis for our algebraic analysis and transformation methods. The framework is based on an embedding of definite logic programs into lazy functional programs in Haskell, such that both the declarative and the operational semantics of the logic programs are preserved. In spite of its conciseness and apparent simplicity, the embedding proves to have many interesting properties and it gives rise to an algebraic semantics of logic programming. It also allows us to reason about logic programs in a simple calculational style, using rewriting and the algebraic laws of combinators. In the embedding, the meaning of a logic program arises compositionally from the meaning of its constituent subprograms and the combinators that connect them. In the second half of the thesis we explore applications of the embedding to the algebraic transformation of logic programs. A series of examples covers simple program derivations, where our techniques simplify some of the current techniques. Another set of examples explores applications of the more advanced program development techniques from the Algebra of Programming by Bird and de Moor [18], where we expand the techniques currently available for logic program derivation and optimisation. To my parents, Sandor and Erzsebet. And the end of all our exploring Will be to arrive where we started And know the place for the first time.