Using default logic to enhance default logic: preliminary report

This paper is about the fusion of multiple knowledge sources represented using default logic. More precisely, the focus is on solving the problem that occurs when the standard-logic knowledge parts of the sources are contradictory, as default theories trivialize in this case. To overcome this problem, several candidate policies are discussed. Among them, it is shown that replacing each formula belonging to minimally unsatisfiable subformulas by a corresponding supernormal default exhibits appealing features.