3.2 Knowledge representation 81
3.2 KNOWLEDGE REPRESENTATION
Two major kinds of knowledge representation are used in classification
learning: the decision tree and the classification rule.
3.2.1 Classification Rules
Classification rules are the simplest representation of classification knowl-
edge. Each classification rule is composed of a condition, which includes one
or more tests, and a conclusion, which associates an instance with the class
to which it belongs. Knowledge rules are expressed in the form “if the attri-
bute X is xxx and the attribute Y is yyy, etc., then the instance Z belongs to
class zzz.” To each class there corresponds a set of relevant attribute values.
After the complete set of rules generated from