Philippe Besnard, Torsten Schaub
We present a new context-based approach to default logic, called contextual default logic. The approach"extends the notion of a default rule and supplies each extension with a context. Contextual default logic allows for embedding all existing variants of default logic along with more traditional approaches like the closed world assumption. A key advantage of contextual default logic is that it provides a syntactical instrument for comparing existing default logics in a unified setting. In particular, it reveals that existing default logics mainly differ in the way they deal with an explicit or implicit underlying context.