Relating defeasible logic to extended logic programs

Defeasible reasoning is a simple but efficient approach to nonmonotonic reasoning that has recently attracted considerable interest and that has found various applications. Defeasible logic and its variants are an important family of defeasible reasoning methods. So far no relationship has been established between defeasible logic and mainstream nonmonotonic reasoning approaches. In this paper we establish close links to known semantics of extended logic programs. In particular, we give a translation of a defeasible theory D into a program P(D). We show that under a condition of decisiveness, the defeasible consequences of D correspond exactly to the sceptical conclusions of P(D) under the answer set semantics. Without decisiveness, the result holds only in one direction (all defeasible consequences of D are included in all answer sets of P(D)). If we wish a complete embedding for the general case, we need to use the Kunen semantics of P(D), instead.