Algorithm rules and sorting method of interval grey numbers based on different “kernel” and the degree of greyness of grey numbers

The interval grey numbers are the basic units of the grey system theory, however, the imperfect algorithm of interval grey numbers seriously restricts the development of the grey system theory. In this paper, the definitions of “kernels” based on the lower measure, the upper measure or the moderate measure are given according to the properties of the interval grey number problems. By means of the measurement error, the appropriate absolute degree of greyness and the relative degree of greyness are defined and different simplified forms of the interval grey numbers are put forward. On this basis, the interval grey number algorithm is established. A new sorting method of the interval grey numbers is proposed according to the “kernel” based on the different measures.