1. A comparison of the commonsense and fixed point theories of nonmonotonicity;Brown,1986
2. On stratified autoepistemic theories;Gelfond,1987
3. Towards a theory of knowledge and ignorance: Preliminary report;Halpern,1984
4. A guide to the modal logics of knowledge and belief: A preliminary draft;Halpern,1985
5. An Introduction to Modal Logic;Hughes,1968