Patent ID: 7496592

Claim:
A computer-implemented method of finding itemsets, said method when executed by a computer comprising the steps of: providing a data stream sliding window; and finding exact closed frequent itemsets over the data stream sliding window; incrementally maintaining a dynamic boundary between closed frequent itemsets and itemsets that are not frequent or that cannot be closed; and providing a closed enumeration tree for storing closed frequent itemsets and other itemsets that define the dynamic boundary; wherein said step of providing a closed enumeration tree comprises: defining at least the following types of nodes in defining the dynamic boundary: infrequent gateway nodes, unpromising gateway nodes, intermediate nodes, and closed nodes; dividing itemsets on the dynamic boundary into at least two categories, wherein one category comprises itemsets on a boundary between frequent and non-frequent itemsets and another comprises itemsets on a boundary between closed and non-closed itemsets; dividing itemsets within the dynamic boundary into at least two categories, wherein one category comprises closed nodes and another comprises intermediary nodes with closed nodes as descendants; and defining specific actions for said categories of itemsets on the dynamic boundary and for said categories of itemsets within the dynamic boundary to maintain the dynamic boundary.