We introduce a generalized definition of SLD-resolution admitting restrictions on atom and/or clause selectability. Instances of these restrictions include delay declarations, input-consuming unification and guarded c...
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We introduce a generalized definition of SLD-resolution admitting restrictions on atom and/or clause selectability. Instances of these restrictions include delay declarations, input-consuming unification and guarded clauses. In the context of such a generalization of SLD-resolution, we offer a theoretical framework to reason about programs and queries such that all derivations are successful. We provide a characterization of those programs and queries which allows to reuse existing methods from the literature on termination and verification of Prolog programs. (C) 2003 Elsevier B.V. All rights reserved.
Linear refinement is a technique for systematically constructing more precise abstract domains for program analysis starting from the basic domain which represents just the property of interest. We use here linear ref...
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Linear refinement is a technique for systematically constructing more precise abstract domains for program analysis starting from the basic domain which represents just the property of interest. We use here linear refinement to construct a domain for pair-independence and freeness analysis of logic programs which is strictly more precise than Jacobs and Langen's domain for sharing analysis endowed with freeness information. Moreover, it can be used for abstract compilation, while Jacobs and Langen's domain can only be used for abstract interpretation. We provide an approximate representation of our domain and algorithms for the abstract operations. We describe an implementation of an analyser which uses abstract compilation over our domain and its evaluation over a set of benchmarks. This shows that its precision is comparable to that of a traditional sharing and freeness analysis performed through abstract interpretation. To the best of our knowledge, this is the first implementation of a sharing analysis based on abstract compilation, as well as the first implementation of a static analysis based on a new domain developed through linear refinement. (C) 2003 Elsevier Science (USA). All rights reserved.
This paper is an overview of our results on the application of abstract interpretation concepts to various problems related to the verification of logic programs. These include the systematic design of semantics model...
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This paper is an overview of our results on the application of abstract interpretation concepts to various problems related to the verification of logic programs. These include the systematic design of semantics modeling various proof methods and the characterization of assertions as abstract domains. We derive an assertion based verification method and we show two instances based on different assertion languages: a decidable assertion language and CLP used as an assertion language. (C) 2003 Elsevier B.V. All rights reserved.
We propose a new framework for the syntax and semantics of Weak Hereditarily Harrop logic programming with constraints, based on resolution over T-categories: finite product categories with canonical structure. Constr...
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We propose a new framework for the syntax and semantics of Weak Hereditarily Harrop logic programming with constraints, based on resolution over T-categories: finite product categories with canonical structure. Constraint information is directly built-in to the notion of signature via categorical syntax. Many-sorted equational are a special case of the formalism which combines features of uniform logic programming languages (moduels and hypothetical implication) with those of constraint logic progamming. Using the cannoical structure supplied by T-categories, we define a diagrammatic generalization of formulas, goals, programs and resolution proofs up to equality (rather than just up to isomorphism). We extend the Kowalski-van Emden fixed point interpretation, a cornerstone of declarative semantics, to an operational, non-ground, categorical semantics based on indexing over sorts and programs. We also introduce a topos-theoretic declarative semantics and show soundness and completeness of resolution proofs and of a sequent calculus over the categorical signature. We conclude with a discussion of semantic perspectives on unifortit logic programming. (C) 2002 Published by Elsevier Science B.V.
Representing defeasibility is an important issue in common sense reasoning. In reasoning about action and change, this issue becomes more difficult because domain and action related defeasible information may conflict...
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Representing defeasibility is an important issue in common sense reasoning. In reasoning about action and change, this issue becomes more difficult because domain and action related defeasible information may conflict with general inertia rules. Furthermore, different types of defeasible information may also interfere with each other during the reasoning. In this paper, we develop a prioritized logic programming approach to handle defeasibilities in reasoning about action. In particular, we propose three action languages and AF(0), AF(1) and AF(2) which handle three types of defeasibilities in action domains named defeasible constraints, defeasible observations and actions with defeasible and abnormal effects respectively. Each language with a higher superscript can be viewed as an extension of the language with a lower superscript. These action languages inherit the simple syntax of A language but their semantics is developed in terms of transition systems where transition functions are defined based on prioritized logic programs. By illustrating various examples, we show that our approach eventually provides a powerful mechanism to handle various defeasibilities in temporal prediction and postdiction. We also investigate semantic properties of these three action languages and characterize classes of action domains that present more desirable solutions in reasoning about action within the underlying action languages.
An elementary formal system (EFS) is a logic program such as a Prolog program, for instance, that directly manipulates strings. Arikawa and his co-workers proposed elementary formal systems as a unifying framework for...
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An elementary formal system (EFS) is a logic program such as a Prolog program, for instance, that directly manipulates strings. Arikawa and his co-workers proposed elementary formal systems as a unifying framework for formal language learning. In the present paper, we introduce advanced elementary formal systems (AEFSs), i.e., elementary formal systems which allow for the use of a certain kind of negation, which is nonmonotonic, in essence, and which is conceptually close to negation as failure. We study the expressiveness of this approach by comparing certain AEFS definable language classes to the levels in the Chomsky hierarchy and to the language classes that are definable by EFSs that meet the same syntactical constraints. Moreover, we investigate the learnability of the corresponding AEFS definable language classes in two major learning paradigms, namely in Gold's model of learning in the limit and Valiant's model of probably approximately correct learning. In particular, we show which learnability results achieved for EFSs extend to AEFSs and which do not. (C) 2002 Elsevier Science B.V. All rights reserved.
Forced oil-water displacement and spontaneous countercurrent imbibition are the crucial mechanisms of secondary oil recovery. Classical mathematical models of both these unsteady flows are based on the fundamental ass...
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Forced oil-water displacement and spontaneous countercurrent imbibition are the crucial mechanisms of secondary oil recovery. Classical mathematical models of both these unsteady flows are based on the fundamental assumption of local phase equilibrium. Thus, the water and oil flows are assumed to be locally distributed over their flow paths similarly to steady flows. This assumption allows one to further assume that the relative phase permeabilities and the capillary pressure are universal functions of the local water saturation, which can be obtained from steady-state flow experiments. The last assumption leads to a mathematical model consisting of a closed system of equations for fluid flow properties (velocity, pressure) and water saturation. This model is currently used as a basis for numerical predictions of water-oil displacement. However, at the water front in the water-oil displacement, as well as in capillary imbibition, the characteristic times of both processes are, in general, comparable with the times of redistribution of flow paths between oil and water. Therefore, the nonequilibrium effects should be taken into account. We present here a refined and extended mathematical model for the nonequilibrium two-phase (e.g., water-oil) flows. The basic problem formulation, as well as the more specific equations, are given, and the results of comparison with an experiment are presented and discussed.
作者：
Yamasaki, SOkayama Univ
Grad Sch Nat Sci & Technol Dept Intelligence Comp & Syst Okayama 7008530 Japan
We are concerned with semantic views on an extended version of SLD resolution with negation as failure (SLDNF resolution) for normal logic programs, which Eshghi and Kowalski (1989) presented by making the SLDNF resol...
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We are concerned with semantic views on an extended version of SLD resolution with negation as failure (SLDNF resolution) for normal logic programs, which Eshghi and Kowalski (1989) presented by making the SLDNF resolution capable of keeping negated predicates in memory and of extracting abducible predicates. This paper deals with its formal representation in relational form, for the purpose of interpreting the normal goal as an acquisitor of negated predicates stored in memory. Some set acquired by the derivations which the normal goal evokes is defined to be a semantics of the goal, under the constraint that the set is as large as possible and does not violate consistency in model theory. The semantics is discussed with relation to the 3-valued logic model theory, where the model theory is represented by alternating fixpoint semantics (Van Gelder, 1993). For simplicity of treatment, this paper is concerned with the normal logic program in the propositional logic.
Laser fusing is a standard technique for improving yield with memory reconfiguration and repair, but implementing fusing in production can be challenging and costly. This article introduces an electrically programmabl...
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Laser fusing is a standard technique for improving yield with memory reconfiguration and repair, but implementing fusing in production can be challenging and costly. This article introduces an electrically programmable polysilicon fuse and shows how it can reduce fuse area and programming complexity.
The different semantics that can be assigned to a logic program correspond to different assumptions made concerning the atoms that are rule heads and whose logical values cannot be inferred from the rules. For example...
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The different semantics that can be assigned to a logic program correspond to different assumptions made concerning the atoms that are rule heads and whose logical values cannot be inferred from the rules. For example, the well founded semantics corresponds to the assumption that every such atom is false, while the Kripke-Kleene semantics corresponds to the assumption that every such atom is unknown. In this paper, we propose to unify and extend this assumption-based approach by introducing parameterized semantics for logic programs. The parameter holds the value that one assumes for all rule heads whose logical values cannot be inferred from the rules. We work within multi-valued logic with bilattice structure, and we consider the class of logic programs defined by Fitting. Following Fitting's approach, we define an operator that allows us to compute the parameterized semantic, and to compare and combine semantics obtained for different values of the parameter. We show that our approach captures and extends the usual semantics of conventional logic programs thereby unifying their computation. (C) 2003 Elsevier B.V. All rights reserved.
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