... In order to identify these equivalents, normalization processing is required, which is mainly performed by sorting the letters representing points of the geometry unit into alphabetical order, so that there is only one writing form for each geometry unit in the system. Taking Triangle (A,B,C) and Triangle (C,A,B) as an example, the processing comprises the following: representing Triangle (A,B,C) with Triangle (1,2,3), and representing Triangle (C,A,B) with Triangle (3,2,1), according to the alphabetical orders of the corresponding letters; respectively sorting Triangle (1,2,3) and Triangle (3,2,1) to Triangle (1,2,3) and Triangle (1,2,3); then comparing the sorted forms. Thus, the system can recognize that Triangle (A,B,C) and Triangle (C,A,B) are equivalents. ...