Termination is well-known to be one of the most intriguing aspects of program verification. Since logic programs are Turing-complete, it follows by the undecidability of the halting problem that there exists no algori...
ISBN:
(纸本)3540206426
Termination is well-known to be one of the most intriguing aspects of program verification. Since logic programs are Turing-complete, it follows by the undecidability of the halting problem that there exists no algorithm which, given an arbitrary logic program, decides whether the program terminates. However, one can propose both conditions that are equivalent to termination and their approximations that imply termination and can be verified automatically. this paper briefly discusses these kinds of conditions that were studied in [2].
this is a slightly enhanced version of the acceptance speech given by the author after receiving the Herbrand Award at the 19thinternationalconference on Automated Deduction (CADE-19) in Miami, Florida, on August 1,...
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this is a slightly enhanced version of the acceptance speech given by the author after receiving the Herbrand Award at the 19thinternationalconference on Automated Deduction (CADE-19) in Miami, Florida, on August 1, 2003. Historical matters related to Herbrand's theorem, higher-order logic, and the author's work are discussed. Contributions by others that have been helpful to the author are noted.
In an important recent paper, Lin and Zhao introduced the concept of a loop formula, and showed that the answer sets for a logic program are exactly the models of Clark's completion of the program that satisfy the...
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In an important recent paper, Lin and Zhao introduced the concept of a loop formula, and showed that the answer sets for a logic program are exactly the models of Clark's completion of the program that satisfy the loop formulas. Just as supported sets are a model-theoretic account of completion, "externally supported" sets, defined in this paper, are a model-theoretic counterpart of loop formulas. this reformulation of loop formulas shows that they are related to assumption sets (Sacca and Zaniolo) and to unfounded sets (Van Gelder, Ross and Schlipf;Leone, Rullo and Scarcello), invented many years earlier. Other contributions of this paper includes a simplification of the definition of a loop, extending it to programs with classical negation and infinite programs, and a generalization of the definition of a loop formula.
logicprogramming and the Prolog language have a major role in Computing. Prolog, and its derived languages, have been widely used in a impressive variety of application domains. thus, a bit of the history of logic Pr...
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logicprogramming is based on the idea that computation is controlled inference. the Extended Andorra Model provides a very powerful framework that supports both co-routining and parallelism. In this work we show that...
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ISBN:
(纸本)3540206426
logicprogramming is based on the idea that computation is controlled inference. the Extended Andorra Model provides a very powerful framework that supports both co-routining and parallelism. In this work we show that David H. D. Warren's design for the EAM with Implicit Control does not perform well for deterministic computations and we present several optimisations that allow the BEAM to achieve performance matching or even exceeding related systems. Our optimisations refine the original EAM control rule demonstrate that overheads can be reduced through combined execution rules, and show that a good design and emulator implementation is relevant, even for a complex system such as the BEAM.
We introduce a general framework for specifying program correspondence under the answer-set semantics. the framework allows to define different kinds of equivalence notions, including previously defined notions like s...
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We introduce a general framework for specifying program correspondence under the answer-set semantics. the framework allows to define different kinds of equivalence notions, including previously defined notions like strong and uniform equivalence, in which programs are extended with rules from a given context, and correspondence is determined by means of a binary relation. In particular, refined equivalence notions based on projected answer sets can be defined within this framework, where not all parts of an answer set are of relevance. We study general characterizations of inclusion and equivalence problems, introducing novel semantical structures. Furthermore, we deal withthe issue of determining counterexamples for a given correspondence problem, and we analyze the computational complexity of correspondence checking.
the current proposals for the inclusion of modules in the ISO Prolog standard are not very consensual. Since a program-structuring feature is required for a production programming language, several alternatives have b...
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ISBN:
(纸本)3540206426
the current proposals for the inclusion of modules in the ISO Prolog standard are not very consensual. Since a program-structuring feature is required for a production programming language, several alternatives have been explored over the years. In this article we recall and expand on the concepts of Contextual logicprogramming, a powerful and simple mechanism which addresses the general issue of modularity in logic Programs. We claim that unit arguments are an essential addition to this programming model, illustrate the claim with examples and draw parallels with Object-Oriented programming. We argue that Contextual logicprogramming is an interesting and effective tool for the development of large-scale programs built upon the Contextual logicprogramming paradigm and argue that contexts with arguments actually provide a powerful, expressive and very convenient means of structuring large applications upon a Prolog basis. We substantiate our claims with examples taken mostly from a "real world" application, Universidade de Evora's Academic Information System, which is currently being developed using the prototype implementation described in this article. We sketch the most relevant aspects of a new implementation of Contextual logicprogramming, GNU Prolog/CX, focusing on the impact on performance of the features which were added to a regular Prolog system, highlighting the low overhead which is incurred in case these extensions are not used.
Many frameworks have been proposed to manage uncertain information in logicprogramming. Essentially, they differ in the underlying notion of uncertainty and how this paper is to allow the reasoning with non-uniform d...
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ISBN:
(纸本)3540206426
Many frameworks have been proposed to manage uncertain information in logicprogramming. Essentially, they differ in the underlying notion of uncertainty and how this paper is to allow the reasoning with non-uniform default assumptions, i.e. with any arbitrary assignment of default values to the atoms. Informally, rather than to rely on the same default certainty value for all atoms, we allow arbitrary assignments to complete information. To this end, we define both epistemologically and computationally the semantics according to any given assumption. For reasons of generality, we present our work in the framework presented in [17] as a unifying umbrella for many of the proposed approaches to the management of uncertainty in logicprogramming. Our extension is conservative in the following sense: (i) if we restrict our attention to the usual uniform Open World Assumption, then the semantics reduces to the Kripke-Kleene semantics, and (ii) if we restrict our attention to the uniform Closed World Assumption, then our semantics reduces to the well-founded semantics.
Among various approaches to explication of Data-Information-Knowledge-Wisdom Hierarchy (DIKW) we advocate a logic-oriented approach. It stems from analysis of the notion of wisdom which often is understood as the abil...
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In this paper, we present a goal-directed proof procedure for ASP with abduction. Our proposed procedure in this paper is correct for any consistent abductive framework proposed in [Kakas90a]. In other words, if the p...
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