T. Eiter, M. Fink, T. Krennwallner, C. Redl, P. Schüller:
"Eliminating Unfounded Set Checking for HEX-Programs";
Talk: 5th Workshop on Answer Set Programming and Other Computing Paradigms (ASPOCP 2012), Budapest, Hungary; 2012-09-24; in: "Proceedings of Answer Set Programming and Other Computing Paradigms (ASPOCP 2012), 5th International Workshop, September 4, 2012, Budapest, Hungary", M. Fink, Y. Lierler (ed.); CoRR - Computing Research Repository, arXiv:1301.1390v1 (2012), 15 pages.

HEX-programs are an extension of the Answer Set Programming(ASP) paradigm incorporating external means of computation into the declarative programming language through so-called external atoms. Their semantics is defined in terms of minimal models of the Faber-Leone-Pfeifer (FLP) reduct. Developing native solvers for HEX-programs based on an appropriate notion of unfounded sets has been subject to recent research for reasons of efficiency. Although this has lead to an improvement over naive minimality checking using the FLP reduct, testing for foundedness remains a computationally expensive task. In this work we improve on HEX-program evaluation in this respect by identifying a syntactic class of programs, that can be efficiently recognized and allows to entirely skip the foundedness check. Moreover, we develop criteria for decomposing a program into components, such that the search for unfounded sets can be restricted. Observing that our results apply to many HEX-program applications provides analytic evidence for the significance and effectiveness of our approach, which is complemented by a brief discussion of preliminary experimental validation.

Answer Set Programming, Nonmonotonic Reasoning, Unfounded Sets, FLP Semantics

http://publik.tuwien.ac.at/files/PubDat_209142.pdf

Project Head Thomas Eiter:
Evaluierung von ASP Programming mit Externen Zugriffen

Project Head Thomas Eiter:
Modulare HEX-Programme

Project Head Thomas Eiter:
Schließen in hybriden Wissensbasen

Project Head Michael Fink:
Inconsistency Management for Knowledge-Integration Systems