VAL@SAIL.STANFORD.EDU.UUCP (02/23/87)
Commonsense and Nonmonotonic Reasoning Seminar REPRESENTING DEFAULTS WITH EPISTEMIC CONCEPTS Kurt Konolige, SRI International Karen Myers, Stanford Thursday, February 26, 4pm Bldg. 160, Room 161K Reasoning about defaults --- implications that typically hold, but which may have exceptions --- is an important part of commonsense reasoning. We present some parts of a theory of defaults, concentrating on distinctions between various subtle ways in which defaults can be defeated, and on the adjudication of conflicting defaults under hierarchic inheritance. In order to represent this theory in a formal system, it seems necessary to use the epistemic concept of self-belief. We show how to express the theory by an almost-local translation into autoepistemic logic, which contains the requisite epistemic operators. Just to be controversial, we also argue that circumscription (pointwise, schematic, prioritized, or otherwise) is insufficient for this task.