A summary on the research of GRA models

Purpose – The purpose of this paper is to review systematically the research of grey relation analysis (GRA) models.Design/methodology/approach – Three different approaches, the springboard to build a GRA model, the angle of view in modelling, and the dimension of objects, are analysed, respectively.Findings – The GRA models developed from the models based on relation coefficients of each point in the sequences in early days to the generalized GRA models based on integral or overall perspective. It evolved from the GRA models which measure similarity based on nearness, into the models which consider similarity and nearness, respectively. The objects of the research advanced from the analysis of relationship among curves to that among curved surfaces, and further to the analysis of relationship in three‐dimensional space and even the relationship among super surfaces in n‐dimensional space.Originality/value – The further research on GRA models is proposed. One is about the property of GRA model. An in‐dept...