Decision Tables: Formalisation, Validation and Verification

The decision table is one of the simplest representations of the rules underlying a systematic decisionmaking process, and is especially valuable in the development of knowledge-based systems. A two dimensional table links all relevant combinations of input conditions to the desired combinations of output actions in a very intuitive way. This simplicity belies the complex considerations involved in verifying, validating, formulating or interpreting this (or any other) representation of machine-based knowledge. In this paper, the common styles of decision table representation are reviewed, a formulation of their meaning is presented, construction methods are reviewed, and an algorithm for ensuring consistency is suggested. The problems that may occur in imperfectly constructed tables are discussed, detection methods reviewed, and some implementation methods are presented.