Rule Induction from Information Tables with Ordinal Decision Attributes

In rough set literature, methods for inducing minimal rules from a decision table have been proposed. When the decision attribute is ordinal, inducing rules about upward and downward unions of decision classes is advantageous in the simplicity of the obtained rules. However, because of independent applications of the rule induction method, inclusion relations among upward/downward unions in conclusion parts are not inherited to the condition parts of the obtained rules. This non-inheritance may debase the quality of obtained rules. To ensure that inclusion relations among conclusions are inherited to conditions, we have proposed rule induction approaches in the previous study. In this paper, the performances of the proposed approaches considering the inclusion relations between conclusions are further examined by numerical experiments using data with a more general structure.