Decision rules

A set of decision rules is the verbal equivalent of a graphical decision tree, which specifies class membership based on a hierarchical sequence of (contingent) decisions. Each rule in a set of decision rules therefore generally takes the form of a Horn clause wherein class membership is implied by a conjunction of contingent observations. IF condition1 AND condition2 AND ... AND conditionn THEN CLASS = classi

where conditionj is in general contingent on the choice of conditionj − 1. Decision rules can be transcribed from the corresponding decision tree, or can be induced directly from observations.