The comparison of the quality of gene order generated by ACO and GA using Euclidean distance. *Ancillary information for figures:1. All microarray data are downloaded from , and the data from the 1st line to 300th line are used to do experiment and for other figures and tables. 2. Every heat map is the optimal gene order, which has the smallest value of fitness function and was selected from tests performed over 40 times. In addition, the distance formula used in the fitness function (see formula 4) is the Euclidean Distance. 3. All of the figures listed in this paper are generated by TreeView, which was developed by Dr Eison, and is downloaded from the website: http://rana.lbl.gov/downloads/TreeView/TreeView_vers_1_60.exe. 4. Because most of the expression levels of the AD gene data are larger than zero, the average value of every column is subtracted when the heat map is shown. Otherwise, all heat maps are red, and the display is incorrect.