By analyzing the advantages and disadvantages of practical applications and the scope of application of the rough set theory as well as a variety of uncertainties in the practical application of knowledge representation systems, this book systematically introduces the hybrid methods and applications of rough set theory and other related soft technology theories. It emphasizes the application of soft computing technology, minimizes the detailed introduction of complicated mathematical formula, and to uses many cases to illustrate the specific application of hybrid methods in order to highlight rough set theory and other soft computing technologies.