(6) Development of Action Language Systems

In this research, we developed a reasoning system called ALP-MGTP, an abductive logic programming (ALP) system in Prolog. In this software, we give an implementation of bottom-up proof procedures for ALP. Our ALP system is a reasoning system for logic programs containing negation as failure (NAF), classical negation, disjunction, and abducible literals. It is based on bottom-up, incremental, backtrack-free computation of the minimal models for disjunctive programs using a model generation theorem prover (MGTP). This system realizes a sound and complete proof procedure for a large class of logic programs, and can deal with abduction and nonmonotonic inference at the same time. This system realizes Inoue and Sakama's fixpoint semantics of ALP. Our ALP system consists of a first-order predicate compiler, which is a translator from ALP rules to MGTP clauses, and modules that translate outputs of MGTP to answers for the ALP framework. The experimental results with some benchmark problems show that our ALP system has a good performance compared with other systems.