shows there is a negative correlation between the IGAC weight and frequency for all three datasets. To confirm this, a correlation analysis is performed by using SPSS 19 . Further comparison shows that they share 54 rules. Moreover, 17 rules exist exclusively in CAC and 47 rules only in IGAC. Table shows the top 20 rules for the classifiers of GAC and IGAC. Among them, 18 rules are the same. All top 20 rules of CAC are included in IGAC while rule 15 and 19 of IGAC are not discovered by CAC. To be noted, although they share many rules, their orders are not the same which may have an impact on the final classification. For instance, rule 3 and 4, 6, 7 and 8 etc. have different orders in these two classifiers. The process of the classification stops immediately when there is a match, so the order of the rules matters. Another major difference between them is that the default class for CAC is "inactive" while IGAC is "active". The default class is used when there is no match can be found, and then the compound will be classified as default class.