Abstract: Due to the complexity and uncertainty of the physical world, as well as the limitation of human ability to comprehend, it is very difficult for the traditional rough set to effectively deal with the real decision making information system consisted of a lot of preference information, grey information and noise data. In view of this, the thought and method of the grey system is used to construct the variable precision rough set model based on dominance grey degree in the paper. The method, to begin with, based on the new results of the grey number and grey degree, the concept of dominance grey degree is proposed to determine the dominance relationship between objects, so that it is used to substitute for the indiscernibility relationship of variable precision rough set, and then the variable precision rough set model based on dominance grey degree is established, and then its natures are discussed, finally an examples is used to validate the effectiveness and applicability of the model. The result shows that the proposed model has a certain tolerant ability by adjusting the threshold parameter, and then it can realize the scientific decision-making by effectively extracting decision rules.

Key words: preference information, grey information, dominance grey degree, variable precision rough set model