Grey relation theory and its applications

The concept and theory of grey relation R(⊗) was put forward by the author in 1989 and was obtained in the process of solving `risk analogy´. At present, grey relation theory has been used with the problems such as `risk decision´, `risk estimate´. The purpose of this paper is to: give the general concept and some theoretical results of grey relation R(⊗); put forward the method on determining grey relative degree R(⊗_i,X_j) between grey element ⊗_i and white element X_j; and give an applied example