1 Mining Closed & Maximal Frequent Itemsets
Mohammed Javeed Zaki · 2003
In this chapter we give an overview of the closed and maximal itemset mining problem. We survey existing methods and focus on Charm and GenMax, both stateof-the-art algorithms that efficiently enumerate all closed and maximal patterns, respectively. Charm and GenMax simultaneously explore both the itemset space and transaction space, and use a number of optimizations to quickly prune away a large portion of the subset search space. We conduct an extensive experimental characterization of GenMax and Charm against other maximal and closed pattern mining methods. We found that the methods have varying performance depending on the database characteristics (mainly the distribution of the closed or maximal frequent patterns by length). We present a systematic and realistic set of experiments showing under which conditions a method is likely to perform well and under what conditions it does not perform well. Overall, both Charm and GenMax deliver excellent