By utilizing the byte characteristic, DFMfi can optimize the mapping and unifying operations on the item sets. Moreover, for the first time a method based on bitmap which uses local maximal frequent item sets for fast superset checking is employed.

• 算法DFMfi充分利用位图的字节特性，优化了项集的匹配和合并操作，并首次在其中引入了基于局部最大频繁项集的超集存在判断方法。