Über normale Vögel, anwendbare Regeln und einen Default-Beweiser

This paper presents the most important approaches to formalizing nonmonotonic reasoning and discusses some difficulties involved in these approaches. For avoiding specific problems arising in applying default rules, a representation form for these rules is suggested which allows the explicit control of their applicability. On the one hand, this helps to avoid unplausible results, on the other, the defaults are maintained in a form familiar to the user.