Abstract: "Recently, contextual logic programming has been proposed as an extension to the logic programming paradigm aiming at structuring programs and logical derivations in a coordinated way ([MP89]). The purpose of this paper is to present and compare various semantics for a parallel versio...

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Hauptverfasser:	Jacquet, Jean-Marie (VerfasserIn), Monteiro, Luís (VerfasserIn)
Format:	Buch
Sprache:	English
Veröffentlicht:	Amsterdam 1990
Schriftenreihe:	Centrum voor Wiskunde en Informatica <Amsterdam> / Department of Computer Science: Report CS 90,18
Schlagworte:	Logic programming Programming languages (Electronic computers) Semantics
Online-Zugang:	Volltext
Zusammenfassung:	Abstract: "Recently, contextual logic programming has been proposed as an extension to the logic programming paradigm aiming at structuring programs and logical derivations in a coordinated way ([MP89]). The purpose of this paper is to present and compare various semantics for a parallel version of it. Six semantics, ranging in the operational, declarative and denotational types, are discussed. Three operational semantics are presented. They all rest on a transition system but differ in their ability of describing success set, failure set, infinite computations and of handling repetitions: i) the first operational semantics just describes the set of atoms having a successful bottom-up derivation ii) the second operational semantics precises, in addition, the computed answer substitutions; iii) the third operational semantics moreover characterizes infinite derivations. As far as the declarative semantics are concerned, a model-theoretic and a fixed-point semantics are examined. They extend the Herbrand interpretation and the immediate consequence operator to our contextual framework. Finally, a denotational semantics based on processes, structured as trees, are [sic] given. The mathematical tools mainly used for these semantics are complete lattices for the declarative semantics and metric spaces for the other ones The parallel logic language under consideration is an elementary one: it uses or-parallelism and and-parallelism in an unrestricted manner. A reconciliation calculus is provided as a way of combining substitutions resulting from the reductions of conjoined goals. Despite its simplicity, we believe that the parallel language still constitutes a model of interest: the results obtained on it -- in particular, the semantical ones -- are bases for results about more elaborated and more practical concurrent versions.
Beschreibung:	24 S.