This book is all about the concept of Rough Set Theory. It is method that deals with the vagueness and uncertainty in the decision making process. The salient feature of intelligent behavior is the ease with which the vagueness or inadequateness is dealt with by the concept. In this theory, the means of expressing vagueness is in terms of boundary regions of a set of objects. At times it is not possible to decide certainly about a particular data, present in a large reservoir of multidimensional data, whether it is present inside the set or not. Rough set is a type of decision making system....