Nowadays the amount of information on the Internet is increasing dramatically.The ability of facilitating users to achieve useful information is more and more important for information retrieval systems. Parch

a model for personalized Internet information retrieval systems is proposed.This model can help users to retrieve what they need by combining class hierarchy with user profile.Several algorithms that use key technologies are proposed

such as data mining

information retrieval and machine learning.These algorithms can make a user profile less manually interfered

more self-adaptive and more accurate

and meanwhile achieve a faster congregating speed in building the class hierarchy by reducing the computing workload.