Vague rough set and its application to knowledge acquisition

Rough set theory is a mathematical method to deal with vague uncertain knowledge and data representation, learning and induction. But in the process of knowledge acquisition, data of the knowledge representation system are required to be precise. The present arithmetic of knowledge acquisition is inapplicable to vague data. The concept of rough sets is extended by idea of vague sets. A new concept - vague rough set - is presented. Its operational character and new knowledge acquisition algorithm are discussed. An example of acquiring rules from vague data is also discussed.