Disclosed is a system and method which systematically diagnoses emissions test failure by applying the rules of a knowledge base to predict the cause of vehicle emissions failures. Classifiers are used to form predictions. The classifier is the data structure used in the automobile emission...http://www.google.de/patents/US5835871?utm_source=gb-gplus-sharePatent US5835871 - Method and system for diagnosing and reporting failure of a vehicle emission test 
