Information modeling has significant influence on factors such as performances, quality, costs and the market competition ability of the product. Polychromatic sets (PS) is a new systematic theory and information-processing tool. This book covers the theoretical foundation, fundamental methods and main topics in complexity system modeling methodology. A crystallization of the authors' work since 2003, the book covers the latest advances in polychromatic theory and its application, providing a state-of- the-art overview of the complexity system modeling.