Computing preferred answer sets by means of answer set programming

摘要

A framework of Prioritized logic programs (PLPs) is useful to represent explicit priorities between literals of logic programs. With its expressive power, PLPs theoretically enable us to realize various frameworks of nonmonotonic reasoning as well as preference abduction. However, so far, its implementation issues have scarcely been provided and even any sound procedure to compute preferred answer sets which give the semantics of PLPs, has not been proposed. In this paper, we present a procedure to compute all preferred answer sets of a PLP in answer set programming. We show soundness and completeness theorems for the procedure. Finally we show that our procedure makes PLPs not only practically available, hut also have the capability of representing the dynamic preferences in addition to static ones.