On the Relation between Reiter's Default Logic and Its (Major)

Default logic is one of the best known and most studied of the approaches to nonmonotonic reasoning. Subsequently, several variants of default logic have been proposed to give systems with properties differing from the original. In this paper we show that these variants are in a sense superfluous, in that for any of these variants of default logic, we can exactly mimic the behaviour of a variant in standard default logic. We accomplish this by translating a default theory under a variant interpretation into a second default theory wherein the variant interpretation is respected.