Document retrieval apparatus

摘要

A document retrieval apparatus is connected to a network, and includes a cluster database storing a cluster of node information elements linked for clustering the documents to a hierarchical tree structure based on degree of similarity in all of the documents. The apparatus can post to an end address in the node information element encountered on the way to follow links of the cluster by whenever one of the documents is updated. Also, the apparatus selects a specific number of documents, clusters those, assigns the remaining non-selected documents respectively to a leaf node to be similar to the documents in the cluster, and repeats recursively the above operations toward a direction of the leaf node of cluster.