Interpretation Of Logic Programs Research Articles

Static analysis of logic programs for independent and parallelism

This paper presents a general-purpose framework for the abstract interpretation of logic programs and applies it to the problem of automatically extracting independent AND parallelism from PROLOG. In this model of parallelism, goals may be executed concurrently only if they cannot access common variables. We present an abstract domain that captures such variable aliasing information with a high degree of accuracy. We then show how this analysis can be used in the compilation of PROLOG clauses into control statements that schedule goals under independent AND parallelism. Our abstract interpretation framework is novel in that it directly addresses the generally acknowledged problem that naive abstract execution is too ineffecient for a practical compiler. Our solution is to precompute a fixed approximation to the meaning of clauses, a process called condensing, allowing specific calls to be abstractly executed without computation of a fixpoint. We show that condensing does not result in a loss of accuracy if the abstract unification operation satisfies certain algebraic properties. We argue that these properties are important even if a more conventional form of abstract execution is employed.

Static analysis of a parallel logic language based on the blackboard model

Shared Prolog is a parallel logic language based on the blackboard interpretation of logic programming. In such an interpretation a logic program is seen as a set of rules executed by a set of agents cooperating via a shared working memory called the blackboard. A distributed interpreter for Shared Prolog was implemented and described in another paper, where the blackboard was a centralized data structure. In this paper we show how the blackboard can be distributed using some static analysis techniques. The basic idea is to perform an abstract interpretation starting from the Shared Prolog operational semantics to generate data structures which represent possible interactions and links among agents. The resulting data structures are used to reduce the number of run time communication operations in an implementation distributed over a network of workstations.

Abstract interpretation of logic programs

article Abstract interpretation of logic programs: an abstract domain for groundness, sharing, freeness and compoundness analysis Share on Authors: Agostino Cortesi Dept. of Mathematics, University of Padova, Via Belzoni 7, I-35131 Padova, Italy Dept. of Mathematics, University of Padova, Via Belzoni 7, I-35131 Padova, ItalyView Profile , Gilbert Filé Dept. of Mathematics, University of Padova, Via Belzoni 7, I-35131 Padova, Italy Dept. of Mathematics, University of Padova, Via Belzoni 7, I-35131 Padova, ItalyView Profile Authors Info & Claims ACM SIGPLAN NoticesVolume 26Issue 9Sept. 1991 pp 52–61https://doi.org/10.1145/115866.115872Online:01 May 1991Publication History 23citation293DownloadsMetricsTotal Citations23Total Downloads293Last 12 Months6Last 6 weeks0 Get Citation AlertsNew Citation Alert added!This alert has been successfully added and will be sent to:You will be notified whenever a record that you have chosen has been cited.To manage your alert preferences, click on the button below.Manage my AlertsNew Citation Alert!Please log in to your account Save to BinderSave to BinderCreate a New BinderNameCancelCreateExport CitationPublisher SiteGet Access

A practical framework for theabstract interpretation of logic programs

There are numerous papers concerned with the compile-time derivation of certain run-time properties of logic programs, e.g. mode inferencing, type checking, type synthesis, and properties relevant for and-parallel execution. Most approaches have little in common, they are developed in an ad hoc way, and their correctness is not always obvious. We develop a general framework which is suited to develop complex applications and to prove their correctness. All states which are possible at run time can be represented by an infinite set of proof trees ( and trees, SLD derivations). The core idea of our approach is to represent this infinite set of and trees by a finite abstract and-or graph. We present a generic abstract interpretation procedure for the construction of such an abstract and-or graph and formulate conditions which allow us to construct a correct one in finite time.

A Logic Programming Language with Lambda-Abstraction, Function Variables, and Simple Unification

It has been argued elsewhere that a logic programming language with function variables and λ-abstractions within terms makes a very good meta-programming language, especially when an object language contains notions of bound variables and scope. The λProlog logic programming language and the closely related Elf and Isabelle systems provide meta-programs with both function variables and λ-abstractions by containing implementations of higher-order unification. In this paper, we present a logic programming language, called Lλ, that also contains both function variables and λ-abstractions, but certain restriction are placed on occurrences of function variables. As a result, an implementation of Lλ does not need to implement full higher-order unification. Instead, an extension to first-order unification that respects bound variable names and scopes is all that is required. Such unification problems are shown to be decidable and to possess most general unifiers when unifiers exist. A unification algorithm and logic programming interpreter are described and proved correct. Several examples of using Lλ as a meta-programming language are presented.

An abstract interpretation scheme for identifying inherent parallelism in logic programs

We describe a new scheme for the abstract interpretation of logic programs. The scheme was developed to identify and integrate different forms of inherent parallelism in logic programs at compile time. The scheme has four components: generalization, abstract unification, summarization and concretization, algorithms for which are discussed. The abstract domain for interpretation consists of type expressions which are used as program modes. The generated mode information has been applied to identify different classes of procedures exhibiting different forms of inherent parallelism. The mode information has also been applied for detection of guards and producer-consumer relationship. The advantages and limitations of our resulting scheme are discussed.

The Parallel Interpretation of Logic Programs in Distributed Architectures

The Parallel Interpretation of Logic Programs in Distributed Architectures

Efficient unification of quantified terms

Conventional logic-programming languages rely fundamentally on symbolic computation with quantifier-free terms. Much theoretical logic uses the richer vocabulary of quantified terms, however. In this paper we sketch some first steps in a program of research for developing data structures and algorithms to support efficient computation directly on quantified terms. We describe a simple concept of quantified term, and efficient unification algorithms for both structure-sharing and non-structure-sharing representations of those terms. The efficiency of the approach results from the techniques used to represent terms, which enable naive substitution to implement correct substitution for quantified terms. The non-structure- sharing unification algorithm described here has been prototyped by modification of a conventional logic-programming interpreter.

A predicate-transition net model for parallel interpretation of logic programs

A predicate/transition net model for a subset of Horn clause logic programs is presented. The syntax, transformation procedure, semantics, and deduction process for the net model are discussed. A possible parallel implementation for the net model is described, which is based on the concepts of communicating processes and relations. The proposed net model offers a syntactical variant of Horn clause logic and has two distinctions from other existing schemes for the logic programs: representation formalism and the deduction method. The net model provides an approach towards the solutions of the separation of logic from control and the improvement of the execution efficiency through parallel processing for the logic programs. The abstract nature of the net model also lends itself to different implementation strategies.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>