Finding reducts for ordinal decision tables

Since its introduction, rough set theory has demonstrated its usefulness in many applications where imprecise and inconsistent information is involved. An important area of its application is in the induction of decision rules for decision problems. Recently, there are studies for applying rough set theory in decision related to ordering where items are ordered by assigning to them an ordinal class label such as excellent, good, fair, bad. In this paper we examine a particular situation of ordinal decision which has not been considered in previous studies. We introduce some new concepts in relation to reducts of such ordinal decision systems and proposed a way to find these reducts using a concept similar to discernibility matrix.