Abstract: Web data grows quickly in the short time，previous FTS may be changed when the sequence database is updated.Re-finding FTS will consume too much execution time and storage space.In this paper，an improved extended lattice，IE-LATTICE is designed to store the previous mining results.An efficient algorithm based on bidirectional constraint，called IM-FTS is proposed，which utilizes the previous results and constraint strategy to discover the new FTS just from the added and deleted part of the database.The analysis and experiments show that IM-FTS algorithm efficiently reduces the average execution time and storage space for mining FTS.

摘要： 由于Web数据增长迅速，先前的频繁序列随着序列库的更新而改变。若重新挖掘频繁序列会增加处理时间和数据存储量。提出一种改进的扩展格结构IE-LATTICE，存储先前的挖掘结果，并在其基础上提出一种基于双向约束的增量挖掘算法IM-FTS，在利用先前结果和约束策略前提下，算法仅从插入和删除序列中发现新的频繁序列。分析和实验表明算法能有效缩减数据处理时间和存储空间。