Dual-normal logic programs – the forgotten class. Issue 4 (3rd September 2015)

• Record Type: Journal Article
• Authors: FICHTE, JOHANNES K.; TRUSZCZYŃSKI, MIROSŁAW; WOLTRAN, STEFAN
• Editors: Eiter, Thomas; Toni, Francesca
• Is Part Of: Theory and practice of logic programming. Volume 15:Issue 4/5(2015)
• Page Start: 495
• Page End: 510
• Publication Date: 2015-09-03
• Subjects: answer set programming, -- classes of logic programs, -- strong and uniform equivalence, -- propositional satisfiability; Logic programming -- Periodicals; Artificial intelligence -- Computer programs -- Periodicals; Constraint programming (Computer science) -- Periodicals; 005.115
• DOI: 10.1017/S1471068415000186
• Languages: English
• ISSNs: 1471-0684

Abstract

Abstract: Disjunctive Answer Set Programming is a powerful declarative programming paradigm with complexity beyond NP. Identifying classes of programs for which the consistency problem is in NP is of interest from the theoretical standpoint and can potentially lead to improvements in the design of answer set programming solvers. One of such classes consists of dual-normal programs, where the number of positive body atoms in proper rules is at most one. Unlike other classes of programs, dual-normal programs have received little attention so far. In this paper we study this class. We relate dual-normal programs to propositional theories and to normal programs by presenting several inter-translations. With the translation from dual-normal to normal programs at hand, we introduce the novel class of body-cycle free programs, which are in many respects dual to head-cycle free programs. We establish the expressive power of dual-normal programs in terms of SE- and UE-models, and compare them to normal programs. We also discuss the complexity of deciding whether dual-normal programs are strongly and uniformly equivalent.