A model of the expanded grey theory

It was a great process to develop from Cantor sets theory to fuzzy theory and grey theory. Based on the process, the author analyzed the essence of grey as viewed from philosophy-mathematics field. Then the grey theory was expanded to higher orders and a hierarchical description was given out. In the description, there existed two indexes (degree of greyness and degree of fuzziness). Finally, based on it, the author bought forward three useful simplified model-building methods. These methods can be added into many advanced methods, such as artificial neural networks and genetic algorithms.