A summary of The progress in grey system research

The progress in grey system research is summarized. The four theories of uncertain systems - probability statistics, fuzzy mathematics, grey system, and rough set theory - are compared. The general grey numbers, the grey sequence operators and several grey system models, which are most commonly used, are introduced, such as the absolute degree of grey incidence model, the grey cluster model based on endpoint triangular whitenization functions, the grey cluster model based on center-point triangular whitenization functions, the grey prediction model of the GM(1,1) model, and the weighted multi-attribute grey target decision model. The reader will get to know a general picture of grey systems theory as a new method for studying problems with partial information known and partial information unknown, especially for uncertain systems with few data and poor information.