Circumscription Convention: “Minimize the extent of P.” (I.e., the only instances of P that hold are those that are forced to hold.) Result: Establishes truth/falsity of every instance of predicate P in the KB. Minimizes the instances of predicate P to those that are forced to be true by the KB. Applications: various, e.g., reasoning about action, default reasoning, taxonomic reasoning (e.g., minimize ab), abductive reasoning, ... Syntactic restrictions: arbitrary formulae, but only first-order definable for certain syntactic classes of KBs. Caveat: Second order in the general case. Comment: Same basic convention as predicate completion but may be applicable to a much broader class of KBs. Many different types of circumscription (e.g., predicate circumscription, variable, parallel, prioritized, pointwise)