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A model building framework for answer set programming with external computations*

Published online by Cambridge University Press:  13 August 2015

THOMAS EITER
Affiliation:
Institut für Informationssysteme, Technische Universität Wien, Favoritenstraße 9-11, A-1040 Vienna, Austria (e-mail: eiter@kr.tuwien.ac.at, fink@kr.tuwien.ac.at)
MICHAEL FINK
Affiliation:
Institut für Informationssysteme, Technische Universität Wien, Favoritenstraße 9-11, A-1040 Vienna, Austria (e-mail: eiter@kr.tuwien.ac.at, fink@kr.tuwien.ac.at)
GIOVAMBATTISTA IANNI
Affiliation:
Dipartimento di Matematica, Cubo 30B, Università della Calabria, 87036 Rende (CS), Italy (e-mail: ianni@mat.unical.it)
THOMAS KRENNWALLNER
Affiliation:
Institut für Informationssysteme, Technische Universität Wien, Favoritenstraße 9-11, A-1040 Vienna, Austria (e-mail: tkren@kr.tuwien.ac.at, redl@kr.tuwien.ac.at)
CHRISTOPH REDL
Affiliation:
Institut für Informationssysteme, Technische Universität Wien, Favoritenstraße 9-11, A-1040 Vienna, Austria (e-mail: tkren@kr.tuwien.ac.at, redl@kr.tuwien.ac.at)
PETER SCHÜLLER
Affiliation:
Computer Engineering Department, Faculty of Engineering, Marmara University, Goztepe Kampusu, Kadikoy 34722, Istanbul, Turkey (e-mail: peter.schuller@marmara.edu.tr)

Abstract

As software systems are getting increasingly connected, there is a need for equipping nonmonotonic logic programs with access to external sources that are possibly remote and may contain information in heterogeneous formats. To cater for this need, hex programs were designed as a generalization of answer set programs with an API style interface that allows to access arbitrary external sources, providing great flexibility. Efficient evaluation of such programs however is challenging, and it requires to interleave external computation and model building; to decide when to switch between these tasks is difficult, and existing approaches have limited scalability in many real-world application scenarios. We present a new approach for the evaluation of logic programs with external source access, which is based on a configurable framework for dividing the non-ground program into possibly overlapping smaller parts called evaluation units. The latter will be processed by interleaving external evaluation and model building using an evaluation graph and a model graph, respectively, and by combining intermediate results. Experiments with our prototype implementation show a significant improvement compared to previous approaches. While designed for hex-programs, the new evaluation approach may be deployed to related rule-based formalisms as well.

Information

Type
Regular Papers
Copyright
Copyright © Cambridge University Press 2015 

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