There are three means to decrease the number of attributes : delete irrelevant attributes to the task using fisher ' s discriminant ratio ; merge correlate attributes according to pearson ' s correlation coefficient ; reduce the dimensionality of the attribute vector by singular value decomposition 在属性选取时根据fisher函数把对分类影响小的属性删除，由pearson ' scorrelationcoefficient将相关联的属性合并，用singularvaluedecomposition减少属性向量空间的维度。
