Reasoning with Forest Logic Programs Using Fully Enriched Automata

Abstract Forest Logic Programs (FoLP) are a decidable fragment of Open Answer Set Programming (OASP) which have the forest model property. OASP extends Answer Set Programming (ASP) with open domains-a feature which makes it possible for FoLPs to simulate reasoning with the expressive description logic SHOQ. At the same time, the fragment retains the attractive rule syntax and the non-monotonicity specific to ASP. In the past, several tableaux algorithms have been devised to reason with FoLPs, the most recent of which established a NEXPTIME upper bound for reasoning with the fragment. While known to be EXPTIME-hard, the exact complexity characterization of reasoning with the fragment was still unknown. In this paper we settle this open question by a reduction of reasoning with FoLPs to emptiness checking of fully enriched automata, a form of automata which run on forests, and which are known to be EXPTIME-complete