循序樣式探勘目的是發掘出頻繁的序列樣式。當循序樣式被發掘出來,後來新到達的樣式可能會因為已存在的這些循序樣式而不被認為是頻繁的序列樣式。漸進式循序樣式探勘的目的就是當序列資料不斷加入,發掘出目前最新的循序樣式,而過時的循序樣式則會被刪除。當序列資料從多個資料串流同時進入時,要維護和更新頻繁的序列樣式就會變得更加困難,更糟的是,當我們考慮到跨多個資料串流的序列,過去被提出的方法就不能有效的探勘頻繁的序列樣式。在本論文中,我們提出一個有效率的PAMS演算法來解決這些問題。PAMS使用PSM樹的資料型態來插入新的項目、更新當前項目、並刪除過時的項目。實驗結果顯示,PAMS在跨多個資料串流的漸進式序列探勘上有顯著的優於其它過去被提出的方法。
Sequential pattern mining is to find frequent data sequences with time. When sequential patterns are generated, the newly arriving patterns may not be identified as frequent sequential patterns due to the existence of old data and sequences. Progressive sequential pattern mining aims to find most up-to-date sequential patterns given that obsolete items will be deleted from the sequences. When sequences come with multiple data streams, it is difficult to maintain and update the current sequential patterns. Even worse, when we consider the sequences across multiple streams, previous methods could not efficiently compute the frequent sequential patterns. In this work, we propose an efficient algorithm PAMS to address this problem. PAMS uses a PSM-tree to insert new items, update current items, and delete obsolete items. The experimental results show that PAMS significantly outperforms previous algorithms for mining progressive sequential patterns across multiple streams.