1. The Logic of Conditionals;Adams,1975
2. Probabilistic Reasoning in Intelligent Systems: Networks of Plausible Inference;Pearl,1988
3. System Z: a natural ordering of defaults with tractable applications to default reasoning;Pearl,1990
4. An introduction to possibilistic and fuzzy logics;Dubois,1988
5. Representing default rules in possibilistic logic;Benferhat,1992