Clustering Categorical Data Streams
  The data stream model has been defined for new classes of applications involving massive data being generated at a fast pace. Web click stream analysis and detection of network intrusions are two examples. Cluster analysis on data streams becomes more difficult, because the data objects in a data stream must be accessed in order and can be read only once or few times with limited resources. Recently, a few clustering algorithms have been developed for analyzing numeric data streams. However, to our knowledge to date, no algorithm exists for clustering categorical data streams. In this paper, we propose an efficient clustering algorithm for analyzing categorical data streams. It has been proved that the proposed algorithm uses small memory footprints. We provide empirical analysis on the performance of the algorithm in clustering both synthetic and real data streams 
Zengyou He, Xiaofei Xu, Shengchun Deng, Joshua Zhexue Huang