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29
Reasoning about Termination of Pure Prolog Programs
 Information and Computation
, 1993
"... We provide a theoretical basis for studying termination of (general) logic programs with the Prolog selection rule. To this end we study the class of left terminating programs. These are logic programs that terminate with the Prolog selection rule for all ground goals. We offer a characterization of ..."
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Cited by 124 (14 self)
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We provide a theoretical basis for studying termination of (general) logic programs with the Prolog selection rule. To this end we study the class of left terminating programs. These are logic programs that terminate with the Prolog selection rule for all ground goals. We offer a characterization of left terminating positive programs by means of the notion of an acceptable program that provides us with a practical method of proving termination. The method is illustrated by giving a simple proof of termination of the quicksort program for the desired class of goals. Then we extend this approach to the class of general logic programs by modifying the concept of acceptability. We prove that acceptable general programs are left terminating. The converse implication does not hold but we show that under the assumption of nonfloundering from ground goals every left terminating general program is acceptable. Finally, we prove that various ways of defining semantics coincide for acceptable gen...
Logic Programming and Knowledge Representation  the AProlog perspective
 Artificial Intelligence
, 2002
"... In this paper we give a short introduction to logic programming approach to knowledge representation and reasoning. The intention is to help the reader to develop a 'feel' for the field's history and some of its recent developments. The discussion is mainly limited to logic programs under the answer ..."
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Cited by 87 (0 self)
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In this paper we give a short introduction to logic programming approach to knowledge representation and reasoning. The intention is to help the reader to develop a 'feel' for the field's history and some of its recent developments. The discussion is mainly limited to logic programs under the answer set semantics. For understanding of approaches to logic programming build on wellfounded semantics, general theories of argumentation, abductive reasoning, etc., the reader is referred to other publications.
Metric Methods Three Examples And A Theorem
, 1993
"... this paper is to demonstrate their utility and simplicity (when they are applicable). We do this by presenting three examples of programs, and a general theorem, all of which are subject to metric methods. One of these is a direct argument that the game program operator T ..."
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Cited by 61 (0 self)
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this paper is to demonstrate their utility and simplicity (when they are applicable). We do this by presenting three examples of programs, and a general theorem, all of which are subject to metric methods. One of these is a direct argument that the game program operator T
Strong Termination of Logic Programs
, 1993
"... this paper appeared as [B]. 1. INTRODUCTION Termination of logic programs is of course of utmost importance. The question whether the topdown evaluation of a goal G terminates with respect to a logic program P is actually underspecified, given the fact that this evaluation may depend on the selecti ..."
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Cited by 51 (1 self)
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this paper appeared as [B]. 1. INTRODUCTION Termination of logic programs is of course of utmost importance. The question whether the topdown evaluation of a goal G terminates with respect to a logic program P is actually underspecified, given the fact that this evaluation may depend on the selection of atoms from goals and on the choice of the program clauses. In this paper termination is considered in the strong sense, i.e. irrespective of the selection of atoms in the goal and of the choice of the program clauses. This is the most demanding notion of termination. Less demanding approaches are: (1) termination for a fixed selection rule and for any choice of program clauses; (2) termination for some selection rule, depending on P, G and annotations on G, and for any choice of program clauses. All approaches can be weakened by requiring termination not for any but only for some
A New Definition of SLDNFresolution
, 1992
"... We propose a new, "topdown" definition of SLDNFresolution which retains the spirit of the original definition but avoids the difficulties noted in the literature. We compare it with the "bottomup" definition of Kunen [Kun89]. 1 The problem The notion of SLDresolution of Kowalski [Kow74] allows ..."
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Cited by 37 (7 self)
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We propose a new, "topdown" definition of SLDNFresolution which retains the spirit of the original definition but avoids the difficulties noted in the literature. We compare it with the "bottomup" definition of Kunen [Kun89]. 1 The problem The notion of SLDresolution of Kowalski [Kow74] allows us to resolve only positive literals. As a result it is not adequate to compute with general programs. Clark [Cla79] proposed to incorporate the negation as finite failure rule. This leads to an extension of SLDresolution called SLDNFresolution. The intuition behind it is quite simple: for a ground atom A, :A succeeds iff A finitely fails, :A finitely fails iff A succeeds. (The restriction to ground atoms was originally introduced to ensure soundness of SLDNFresolution. ) However, this intuition is difficult to formalize. For example, consider the general program P = fA /Ag. The query :A neither succeeds nor finitely fails, since the query A neither succeeds nor finitely fails. So it is...
Representing Actions: Laws, Observations and Hypotheses
 Journal of Logic Programming
, 1997
"... We propose a modification L 1 of the action description language A. The language L 1 allows representation of hypothetical situations and hypothetical occurrence of actions (as in A) as well as representation of actual occurrences of actions and observations of the truth values of fluents in actual ..."
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Cited by 34 (3 self)
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We propose a modification L 1 of the action description language A. The language L 1 allows representation of hypothetical situations and hypothetical occurrence of actions (as in A) as well as representation of actual occurrences of actions and observations of the truth values of fluents in actual situations. The corresponding entailment relation formalizes various types of commonsense reasoning about actions and their effects not modeled by previous approaches. As an application of L 1 we also present an architecture for intelligent agents capable of observing, planning and acting in a changing environment based on the entailment relation of L 1 and use logic programming approximation of this entailment to implement a planning module for this architecture. We prove the soundness of our implementation and give a sucient condition for its completeness.
Constraintbased Termination Analysis of Logic Programs
 ACM Transactions on Programming Languages and Systems
, 1999
"... Current normbased automatic... In this paper we present a new termination analysis which integrates the various components and produces a set of constraints that, when solvable, identifies successful termination proofs. The proposed method is both efficient and precise. The use of constraint sets e ..."
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Cited by 34 (15 self)
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Current normbased automatic... In this paper we present a new termination analysis which integrates the various components and produces a set of constraints that, when solvable, identifies successful termination proofs. The proposed method is both efficient and precise. The use of constraint sets enables the propagation of information over all different phases while the need for multiple analyses is considerably reduced.
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...
Towards a New Massively Parallel Computational Model for Logic Programming
 PROCEEDINGS OF THE ECAI94 WORKSHOP ON COMBINING SYMBOLIC AND CONNECTIONIST PROCESSING, ECCAI
, 1994
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