default rules

views updated

default rules A method for resolving conflicts and dealing with inconsistencies that arise in inheritance systems and nonmonotonic reasoning. Default rules can contain components that define normality so that exceptions do not cause conflicts. For example, knowing that birds fly and Fred is a bird is inconsistent with knowing that Fred is a penguin. Attaching a “normal” predicate to the rule that birds fly and knowing that penguins are not normal birds resolves the problem.